Reference Material CPC30608 CERTIFICATE III IN PAINTING & DECORATING
Reference Material CPC30608 v1.2.docxCreated 27/07/2010 9:44:00 PM
Version information: Title:
Reference Material
Based on Training Package:
CPC30608
No.
Date
Nature of revision
V1.2
13/01/11
Version
Version: Developed by:
Michael Farrugia
Every care has been taken to ensure that the information in this Reference Material is correct, but trainers are advised to check the currency and the relevance of the content to their own training package. Acknowledgments: • •
Basic Building & Construction Skills handbook 3rd edition – published by Pearson Education Australia Australian New Zealand Standards association – published by standards Australia George Englert – Dec Con Construction Training Queensland Building Construction Industry Training Fund Australian National Training Authority Master Painters Association Training Advisory Group Environmental Health Unit of Queensland Public Health Services, Queensland Health Dallas King – Southern Queensland Institute of TAFE Craig Prout & Dan Walker- Sunshine Coast Institute of TAFE Trevor Baker – Great Barrier Reef TAFE Rod Pearce – Southern Queensland Institute of TAFE Len Mason – Skillstech Glenn Iddon – Skilltech David Beamish - DeFelsko Corporation, Ogdensburg, NY
• • • • • • • • • • • • • • • If you are aware that you have not received due acknowledgment or have not given permission for anything that was produced in this publication please contact Michael Farrugia by email michael.farrugia@aptc.edu.au “This is not a commercial publication. It is designed to assist students in acquiring underpinning knowledge of the paint & decorating trade. If you feel that plagiarism has occurred please accept my sincere apology and notify me via my email so I can correct this mistake.”
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Contents Contents ........................................................................3 1
Occupational Health & Safety...................................9 1.0 Introduction ............................................................ 9 1.1 Risk Management ................................................... 9 1.2 Chemical Hazards ................................................. 11 1.3 Safe Materials Handling and Storage..................... 13 1.4 JSA/Safe Work Method Statement ........................ 13 1.5 Manual Handling .................................................. 13 1.6 Personal Protective Equipment (PPE)..................... 16 1.7 Barrier/Barricade &Signage .................................. 18 1.8 Emergencies First Aid, Accidents and Injuries ...... 19 1.9 OH&S Policies, Procedures & Legislation............... 23 1.10 Working at heights .............................................. 23
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Quality Requirements ............................................ 27 2.0 Introduction .......................................................... 27 2.1 Quality Requirements ........................................... 27 2.2 Painting & Decorating Industry Sectors ................ 29 2.3 Heritage Restoration ............................................. 30 2.4 Responsibility of Applicators ................................. 33 2.5 Workplace Communication ................................... 35 2.6 Planning & Organising to Work Effectively ............ 46
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Calculations & Measurements ................................ 47 3.0 Introduction .......................................................... 47 3.1 Measurements ...................................................... 47 3.2 Calculations .......................................................... 48 3.3 Ratios ................................................................... 51 3.4 Wallpaper & Lining paper...................................... 53
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Plans & Specifications ............................................ 57 4.0 Introduction .......................................................... 57
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4.1 Scales, Key, Contours, Symbols & Abb reviations .. 57 4.2 Specifications ........................................................ 60 4.3 Types of Drawings ................................................. 60 5
Industry Terminology ............................................ 65 5.0 Introduction........................................................... 65 5.1 Glossary of terms ................................................... 65
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Spontaneous Combustion ...................................... 81 6.0 Introduction........................................................... 81 6.1 Prevention of Spontaneous Combustion................. 81
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Tools, Equipment and Materials ............................ 83 7.0 Introduction........................................................... 83 7.1 Brush ware ............................................................ 83 7.2 Rollers ................................................................... 90 7.3 Hand Tools ............................................................ 96 7.4 Power Tools ........................................................... 99 7.5 Abrasives ............................................................. 101 7.6 Chemicals ............................................................ 104 7.7 Filling & Stopping materials................................. 109
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Plan & Prepare for Painting & Decorating ............ 113 8.0 Introduction......................................................... 113 8.1 Prepare work Area ............................................... 114 8.2 Choosing the correct tools ................................... 116 8.3 Choosing the correct materials ............................ 116 8.4 Identifying the substrate ...................................... 117
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Coating Technologies .......................................... 125 9.0 Introduction......................................................... 125 9.1 Paint Ingredients ................................................. 125 9.2 Gloss levels of Paint Finishes ............................... 130 9.3 How Paint Dries ................................................... 132 9.4 Paint Systems ...................................................... 134
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9.5 Selecting Paint Systems ...................................... 136 10 Coating Defects .................................................... 139 10.0 Introduction ...................................................... 139 10.1 Types of Paint Coat Defects ............................... 139 11 Paint Application Testing ..................................... 149 11.0 Introduction ...................................................... 149 11.1 Non-Destructive Dry Film Methods ................... 149 11.2 Destructive Dry Film Methods ........................... 152 11.3 Wet Film Methods ............................................. 152 11.4 Determining Existing Coatings .......................... 154 12 Surface Preparation .............................................. 155 12.0 Introduction ...................................................... 155 12.1 Preparation of Unpainted Timber ...................... 155 12.1 Preparation of Unpainted Metal......................... 160 12.2 Preparation of Unpainted Masonry .................... 163 12.3 Preparation of Unpainted Plasterboard.............. 166 12.4 Preparation of Unpainted Plastics ..................... 167 12.5 Preparation of Unpainted Asbestos ................... 167 12.6 Removal of Paint ............................................... 168 12.4 Removal of Wallpaper ........................................ 174 13 Substrate Repairs ................................................. 177 13.0 Introduction ...................................................... 177 13.1 Repairing Discolouration of Paint Films ............ 177 13.2 Plasterboard repairs .......................................... 180 13.3 Concrete & Cement Render Repairs .................. 183 13.4 Metal Repairs .................................................... 187 13.5 Timber Repairs.................................................. 187 14 Apply Texture Coatings ........................................ 191 14.0 Introduction ...................................................... 191 14.1 Planning ........................................................... 192 Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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14.2 Application of Texture ........................................ 196 14.4 Trowel on Texture .............................................. 197 14.5 Information on Texture Coatings........................ 197 15 Apply Paint by Spray ........................................... 199 15.0 Introduction....................................................... 199 15.1 General Preparation for Spraying ....................... 199 15.2 Conventional Spraying ....................................... 200 15.3 Troubleshooting conventional guns.................... 209 15.4 Conventional Spray Gun Technique ................... 212 15.5 Airless Spray System ......................................... 214 16 Apply Stains & Clear Timber Finishes .................. 225 16.0 Introduction....................................................... 225 16.0 Preparing Timber for clear finishes .................... 225 16.2 Stopping & Filling .............................................. 226 16.3 Stains ................................................................ 228 16.4 Clear Finishes .................................................... 230 17 Wallpaper ............................................................ 233 17.0 Properties of Wallpaper ...................................... 233 17.1 Label Information .............................................. 241 17.2 Prepare the area ................................................ 243 17.4 Size & Adhesives ................................................ 245 17.5 Wallpaper Application ........................................ 248 18 Graffiti & Prevention ........................................... 251 18.0 Introduction....................................................... 251 18.1 Graffiti Removal ................................................. 252 18.2 Anti Graffiti Paints ............................................. 253 19 Industrial Coatings .............................................. 257 19.0 Corrosion ........................................................... 257 19.1 Durability Considerations .................................. 259 19.2 Classification of environment ............................. 260 Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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19.3 Design Considerations ...................................... 262 19.4 Protective Coatings............................................ 263 20 Manage Lead and Asbestos Hazards ...................... 269 20.0 Introduction ...................................................... 269 20.1 Health Effects ................................................... 269 20.2 Testing Paint for Lead ....................................... 270 20. 3 Managing Lead & Asbestos Hazards ................. 271 20.4 Lead Abatement ................................................ 272 20.5 Procedures for Lead Paint Removal ................... 273 20.6 Decontamination & Clean up ............................ 274 20.7 Stabilisation of Lead & Asbestos ....................... 275 20.8 Encapsulation ................................................... 275 20.9 Information ....................................................... 276 21 Glaze Windows ..................................................... 277 21.0 Introduction ...................................................... 277 21.1 Safety Handling Glass ....................................... 277 21.2 Qualities & Characteristics of Glass .................. 277 21.3 Glazing Techniques ........................................... 278 Appendix I - Useful Web Sites ..................................... 279 Appendix II - Paint Systems – AS/NZ2311 .................. 281 Appendix III Paint Types – AS/NZ2311....................... 291 Appendix III – Additional Information & Fact Sheets.. 301
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1
Occupational Health & Safety
1.0 Introduction
Each year, there are thousands of incidents and illnesses occur in workplaces throughout Australia and the Pacific. Direct financial costs arising from workers compensation, hospitalisation, rehabilitation, lost production and staff retraining is estimated to directly cost the community large sums of money each year. For workers, the human costs of injury can be equally devastating. Pain, discomfort and rehabilitation are often accompanied by other psychological stressors, mainly emotional stress, strained relationships, uncertainty and general disruption to daily life.
1.1 Risk Management
Risk management The risk assessment process is our main tool when discussing safety issues. Risk assessments should be carried out for all hazardous activities, especially unfamiliar workplaces or work activities. •
A hazard is anything with the potential to cause injury or illness.
•
A risk is the likelihood the hazard will result in an injury or illness.
•
A risk assessment evaluates the risk associated with the hazard.
Risk management procedure: 1. Identify the hazard – spot the hazard 2. Assess the risk – what can happen 3. Determine control measures – fix the problem 4. Evaluate the outcome – does it reduce the risk Risk assessments are a major part of “work method statements” i.e. how a workplace activity is to done with minimal risk.
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Types of hazards An obvious hazard stands out as being dangerous e.g. a worker not wearing safety boots or glasses. An apparently trivial hazard is one that a worker thinks is of little importance e.g. the wearing of loose clothing that could get caught in machinery. A hidden hazard is one that is not obvious to the eye e.g. a crack in the rung of a ladder. A developing hazard is one that is safe at the moment but will worsen in the future e.g. rain affected trench excavation. Aim at removing possible causes of accidents as soon as you become aware of them by reporting them to your supervisor without delay or by removing them yourself if you can do so safely. Risk management is a proactive process of controlling hazards at the workplace and involves: Spotting the hazard Assessing the risk Fixing the problem Evaluate the outcome Spotting the hazard A hazard is anything with the potential to cause injury or illness. Some common types of hazards associated with most industries include: plant, manual handling, electricity and hazardous substances. Assessing the risk Having identified the hazards in your workplace, the next step is to assess the risk of those hazards. The risk is the likelihood the hazard will cause injury or illness. Assessing the risk is a simple process, which considers the following: The probability of the hazard resulting in an injury The length of exposure to the hazard Possible consequences that may occur
Probability X Exposure X Consequence = Level of Risk
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Fixing the problem Having spotted the hazards and assessed the risk of injury, employees without supervisory responsibilities should report hazards to designated personnel. Designated personnel may include supervisors, managers or other personnel in control of the workplace. Having approached these designated personnel, it is the employer’s responsibility to then solve the issue and provide a safe workplace. Nearly all workplace hazards can be minimised or controlled. Management can choose to control the hazard in a number of ways. The following hierarchy of controls provide a range of mechanisms to manage hazards at the workplace. Those at the top of the hierarchy are considered ideal, since they control the hazard at their source. Other lower order controls such as personal protective equipment (PPE) simply control the worker’s exposure to hazards. However, all controls can be effective, if carried out properly. Eliminate the hazard – removing disused chemicals Substitute the hazard – using a less toxic chemical Engineering the hazard – ventilation stack Administration - safe work procedures, restrict access, rotate workers Personal protective equipment (PPE) – respirator, boots, hard hats, etc. Evaluate the outcome To see how effective the risk has been minimised or whether there has been any secondary hazards generated by the control measures e.g. loose tight weave clothing used to protect from the sun do not get caught in revolving machinery.
1.2 Chemical Hazards
Many substances used at the workplace have the potential to cause injury or illness. Increasingly, new chemicals, solvents and other substances continue to enter the workplace. Hazardous substances can come in the form of a solid, liquid or gas. It is believed that there are many deaths each year, which is not correctly identified as caused by exposure to hazardous substances at work. This figure could be as high as 4 – 5 times the reported deaths.
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What are Hazardous Substances? Hazardous substances are dangerous. Substances can affect the body by being a: •
Carcinogen – cause cancer
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Mutagen – cause cell mutations that can be passed onto to children
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Teratogen – damages developing foetus
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Systemic toxin or poison – harm body organs like the liver, kidney, brain, etc
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Asphyxiants – interfere with breathing
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Corrosive – damage to skin
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Sensitiser – make person sensitive to substances
One very important way to find out about chemicals is interpreting information through a material Safety Data Sheet (commonly called by its acronym ‘MSDS’). By using a MSDS you can: •
check that the chemical is being used in the right way for the right job decide whether any improvements should be made to machinery or work practices
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decide whether any environmental monitoring should be done
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check that the site emergency equipment and procedures are adequate
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be aware of any health hazards
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store the chemical properly
Using solvent to clean your hands will remove essentials oils in the hands leading to dermatitis. Dermatitis can happen immediately at point of contact. Long-term exposure to solvent vapour will affect the circulatory, respiratory and nervous systems.
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1.3 Safe Materials Handling and Storage
The painter & decorator needs to implement and maintain safe housekeeping practices, including: •
safe systems for collecting, storing and disposing of excess or waste materials
•
adequate space for the storage of materials and plant
The benefits from correctly and safely storing materials are:
1.4 JSA/Safe Work Method Statement
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You are less likely to injure yourself or cause others injury by over reaching or lifting incorrectly from an awkward location.
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You will waste less material if you can easily identify when you need to restock an item. You will also avoid damaging materials such as wallpaper etc that would need to be replaced.
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You will also reduce the chance of spills or leakage through damaging containers that have been incorrectly stored.
Work method statements (also known as a JSA – Job Safety Analysis in some states of Australia) are a compulsory part of any site safety management plan and should form part of the planning for any risky site task. A Work Method Statement is a document which describes the job to be completed, outlines the steps involved, the hazards associated with the work and the controls to be implemented to ensure that the work is completed safely. Work Method Statements are completed by the contractor company as the contractor is expected to be experienced in the work and the hazards associated with it. You will be asked to complete a number of work method statements for activities that you undertake during your training. Your trainer will assist you with this.
1.5 Manual Handling
Manual tasks are those workplace activities requiring the use of force exerted by a person to grasp, manipulate, strike, throw, carry, move (lift, lower, push, pull), hold or restrain an object, load or body part. Manual tasks therefore cover a wide range of activities including using a chain saw, stacking shelves, working on conveyor line, entering data into a computer and directing traffic.
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What are the risk factors? Direct stressors: directly stresses the body. They include factors such as the level of muscular force exerted, working postures, repetition of actions, the vibration absorbed from equipment and the duration of time these conditions are sustained
Forceful exertions Working posture Repetition and duration Vibration
Contributing risk factors: directly influence the task demands. They include the work area layout, use of tools, nature of loads, and load handling. If these components are redesigned, the impact of the direct stressors can be reduced.
Work area design
Modifying risk factors: can contribute to a further change in the impact of other risk factors.
Individual factors
Hand tool use Nature of loads Load handling
Work organisation
Vibration is also an area of major concern There are two forms of vibration exposure according to the contact points between the body and the vibrating equipment: •
Localised vibration: from hand and power tools can produce ‘vibration white finger’, where the blood vessels and nerves of the hand and the wrist can be permanently affected.
•
Whole body vibration: can occur when driving vehicles or using machinery or equipment can produce headaches, affect vision and digestion, and cause progressive deterioration of the spine.
Manual handling includes Occupational Overuse Syndrome (OOS). OOS is a result of using repetitive actions that aggravate tendons causing prolonged swelling and soreness. To help in preventing or minimising risks from manual tasks, workers should: •
Take part in activities to identify, assess and control the risks of musculoskeletal disorders.
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Report to the employer or supervisor:
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Problems with the performance of a manual task.
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Discomfort or symptoms that indicate there may be a problem with a task.
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Problems with the maintenance of equipment.
The spine The most significant group of injuries when relating to manual handling is that of back problems caused by poor manual handling practices. The spine protects the spinal cord and supports support the weight of the body. The human spine is built up of block like bones (vertebrae) ( stacked one on top of the other and held in place with leather like strips ((ligaments). Between the vertebrae are pads of elastic cartilage welded to the bones. These are shock absorbers and are called intervertebral discs - the site of most of our back problems. problems It is the lower back (lumbar) area where most of the problems occur. This is the area of concentration of most manual handling stresses, especially on the lower three vertebrae. The problem is compounded, because the torso (lower back region) is already carrying much of the body mass above the torso, add poor posture and you may already have a problem. Lifting Lifted incorrectly by leaning forward, sideways or twisting, it is possible for a 10Kg load to become a 700Kn force on your back. One of the saddest aspects of a manual handling injury, particularly one of the back, is that a person may never recover their level of health and suffer for the rest of their lives. Poor manual handling techniques and bad posture will lead to very prompt physical tiredness. Continued ba bad d work practices will lead to long-term long repetitive injury e.g. jumping off scaffold instead of using ladders, jumping across trenches instead of planking. If the load is beyond you’re lifting capacity get mechanical assistance, team lift, split the load to name a few alternatives.
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1.6 Personal Protective Equipment (PPE)
The type of PPE to be worn is dictated by site specific rules, designated areas or due diligence. Site specific rules are site/workplace policies or procedures about the type of PPE to be worn at the workplace. Designated areas are identified by blue signs (mandatory – must be worn) e.g. safety boots Due diligence is where you think certain PPE is required and should be worn When selecting PPE consult the manufacturer or safety equipment distributor for advice on selection, maintenance, storage requirements and training in correct use of PPE. Basically, there are five things to remember about PPE: •
Have it with you every day.
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Use it.
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Keep it in good order (replace it if it’s faulty or damaged).
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Obey all signage relating to PPE
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Consult the Codes of practice Personal Protective Equipment for more information.
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All PPE used at a workplace must be in accordance with the relevant Australian Standard.
Safety helmets (AS1801) The hard hat is one of the most common pieces of PPE where there is a risk of falling objects. Surviving one bad knock on the head will more than make up for the inconvenience of wearing it. Some simple tips on using and maintaining a hard hat: Adjust the headband so it’s if it’s snugly and comfortably. (Test by touching your toes if the helmet falls off, it’s too loose.) Attach a chin strap to keep it on in high wind conditions. Replace the harness inside the hard hat every two years. Replace hard hat if it gets damaged. Always wear it. Conditions at the workplace can change quickly especially on a construction site. There is no such thing as a hazard free zone on a construction site. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Safety footwear (AS2210) Even a minor foot injury can put you out of action and cost you wages. Thongs are not acceptable footwear at a workplace. Consult your company’s footwear policy on acceptable footwear. Workshops and construction sites are considered high risk so steel cap boots must be worn. Some tips for footwear: •
Footwear should have strong uppers, resilient and rigid soles, comfortable and protective steel toe caps.
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Damaged or worn-out footwear must be replaced.
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Check the grip on the soles regularly.
Hand protection (AS2161) Hand injuries are by the most common injuries at the workplace. To prevent hand injuries, there is a wide range of purpose made gloves, mittens and barrier creams for handling everything from welding gear to hazardous substances and chemicals. Eye protection (AS1336 & 1337) After hand injuries, injuries to the eyes are most frequent. Like gloves, eye protection gear is available in a wide range of types from goggles to full face mask. Apart from obvious dangers, like welding, damage to your eyes can be caused by: •
Metal and wood shavings
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Flying nails
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Chemical dust and splashes
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Tools and equipment being used by nearby workers
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Outdoor work
Hearing protection (AS2161) It doesn’t take a lot to permanently damage your hearing. The noise level of a common power saw (110 decibels) is enough to cause damage. It can take as little as two minutes a day of unprotected exposure to a power saw cutting metal to permanently reduce your hearing. Obtain some approved protective ear plugs or ear muffs and develop the habit to wear them.
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Respiratory protection (AS1716) Vapour from many common glues, solvents, chemicals and finishes can damage the membrane in your nose, the air passages in your throat and your lungs. Othe Otherr real dangers for the respiratory system are dust and fine fragments from sawing, drilling and welding which become airborne are inhaled. In most cases you may only need an approved disposable mask suitable for the task. If a more sophisticated respirator is needed, make sure one is available and that you use it. Protective clothing (AS2919) Material Safety Data Sheets (MSDS) will generally show the personal protective equipment required. Read the instructions and warnings on the packaging or label then consult nsult the appropriate MSDS and wear the necessary PPE. While they may be uncomfortable in hot weather, protective aprons, coats or body suits will minimise the risks of being serious injured by hot, poisonous or corrosive liquids or solids. Harnesses (AS/N (AS/NZ1891) Effective when working at height greater than 3m only. Wear an approved harness and attach the other end of the lanyard (lifeline) to a suitable anchor point. You should also put on a harness when entering confined spaces and station an observer at the anchor end of the lanyard to help you if necessary. Always ensure the harness is in good working order, adjust it so it fits comfortably and check the lifeline is not frayed of chafed.
1.7 Barrier/Barricade &Signage
Safety barriers/barricades and signs are to comply with relevant Australian Standards, and used where recommended by legislation or the outcome of a risk assessment. Safety barriers, barricades and guards A safety barricade/barrier/guard should be used when there is a likelihood of: Where person or material are likely to fall (Barricade). Person entering a hazardous area (Barrier). Persons becoming entrapped in revolving machinery (Guarding).
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Do not enter areas that have barriers erected unless you are authorised and you are aware of the hazards in that area. Never operate machinery without guards in place. Always replace all guards before starting machinery. Safety signs Safety signs are classified according to functional use. There are 4 main types of signs: Regulatory signs: Prohibition – Red, White & Black - No Smoking Mandatory - Blue & White - Eye protection must be worn Limitation or Restriction - Red & White - Speed limits Hazard signs: Danger - Red, White & Black - Danger Confined Space Warning - Black & Gold - Crane overhead Emergency signs: Green & White - First Aid Fire: Red - Fire Hose Reels Safety signs should be: Erected approx 1500mm from the ground and as close as practical to the item that the sign refer to and kept clear and clean at all times and OBEYED!
1.8 Emergencies First Aid, Accidents and Injuries
Emergencies may develop on a job site due to equipment failure, a dangerous event such as scaffold collapse, fire or even an explosion. Unfortunately you may even need to administer basic first aid. Have you participated in a first aid course? Can you perform CPR? These are very important skills to have on site. Perhaps you could make it a goal to gain these skills. Let’s look at some emergencies that could occur on your site and discuss how to these can be managed. Fire The first thing to keep in mind about fire is that is much better to prevent fire then fighting a fire out once it starts.
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The following are some practical suggestions on how to prevent a fire: •
Remove unwanted fuel and rubbish
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Store fuel and combustible materials carefully
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Use only approve electrical fittings
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Don’t overload electrical circuits
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Don’t smoke in the work place
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Take special care when working with flammable liquids or gases
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Be careful of oily rages which can ignite with spontaneous combustion.
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Avoid dust hazards many types of dust are highly flammable
Site evacuation Do not panic Obey instructions from authorised personnel Follow the site’s evacuation procedure Assemble at the designated evacuation location First Aid First – THIS IS NOT A FIRST AID COURSE! In this section we will highlight some important things to remember when encountering a causality. These basic points are important and may save a life. Priorities •
assess the situation – do not put yourself in danger;
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make the area safe;
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assess all casualties and attend first to any unconscious casualties;
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Send for help – do not delay.
Check for a response Ask loudly, ‘Are you all right?’ Shout for help; If the casualty is breathing normally: Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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•
place in the recovery position;
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get help;
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Check for continued breathing.
Recovery position Cardial pulmonary resuscitation If you have never done a first aid course then we strongly recommend that you do this at least once in your life. CPR can and has saved lives! If there is severe bleed bleeding: •
apply direct pressure to the wound;
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raise and support the injured part (unless broken);
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Apply a dressing and bandage firmly in place.
Amputations Keep body part clean, dry and cool (but not on ice) GO STRAIGHT O HOSPITAL! Broken Bones If a broken bo bone ne or spinal injury is suspected, obtain expert help. Do not move casualties unless they are in immediate danger.
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Spinal injuries are very serious! If you move a person with a suspected spinal injury you may kill the person or put them in a wheel chair.
Burns Burns can be serious so if in doubt, seek medical help. Cool the affected part of the body with cold water until pain is relieved – Go to hospital! Chemical Burns Avoid contaminating yourself with the chemical. Treat in the same way as for other burns Continue treatment even on the way to hospital, if necessary. Remove any contaminated clothing.
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Eye injury All eye injuries are potentially serious. If there is something in the eye: •
Wash out the eye with clean water or sterile fluid from a sealed container, to remove loose material.
•
Do not attempt to remove anything that is embedded in the eye.
If chemicals are involved, flush the eye with water or sterile fluid, while gently holding the eyelids open. Ask the casualty to hold a pad over the injured eye. Send them to hospital.
1.9 OH&S Policies, Procedures & Legislation
You will be required to undertake participation in CPCCOHS1001A ‘Work safely in the construction industry’ APTC School of ACEM orientation Through these programs you will be introduced to OH&S policies, procedures & legislation for the construction industry and your obligations as a student of APTC/ACEM.
1.10 Working at heights
Risks must be managed if a person could fall less than 3 metres (housing construction), 2 metres (other construction) or if work is on a roof pitch not more than 26°. Hazards that may present a risk from a fall include: •
vertical reinforcing steel, the edge of a rubbish skip, a picket fence, or a stack of bricks below workers
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un-sheeted floor bearers and joists 2 metres below workers
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Work on a brittle roof.
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Factors such as the type of activity being carried out should be taken into consideration to establish the degree of risk.
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Control measures used to manage risks must comply with regulatory requirements.
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Relevant people carrying out work above these heights or on a roof pitch more than 26° must: •
prevent a fall; or
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If prevention is not possible, arrest the fall and prevent or minimise the risk of death or injury from the arrest of the fall.
The controls could include: Edge protection systems around elevated work areas must: •
be erected and used in accordance with the instructions of the manufacturer, supplier, engineer or competent person
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be designed to withstand a force which may reasonably be expected to fall against it
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be at least 900 mm high.
A fall protection cover placed over holes and openings must be: •
able to withstand the impact of a fall onto it of any person who may reasonably be expected to fall onto it
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securely fixed in place to prevent it being moved or removed accidentally.
A travel restraint system is a personal fall prevention device and must: •
not allow a free fall either from an edge or through the work surface
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be installed by a competent person and be inspected by a competent person at least every six months (a written record of the inspection must be obtained)
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have an anchorage point with a capacity to withstand any load that could be exerted on it in its normal operation
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only be used by a person who has been trained in the safe and correct use of the system
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not to be used if a component of the system shows evidence of wear or weakness to an extent that may affect the system's safety.
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A fall arrest system consisting of harnesses or ladder belts attached by lanyards to a suitable anchor point must: •
have each anchorage point designed by an engineer and inspected and approved by a competent person before it is first used
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have each anchorage point located so that the person using the system can attach a lanyard without the risk of falling
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be installed and maintained in accordance with the instructions of the manufacturer, supplier, engineer or competent person
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have sufficient free fall distance taking into consideration:
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the person's height
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the height and position of the anchorage point
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the length of the lanyard
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any slack in the static line
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any stretching of the lanyard or static line when extended by a fall
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the length of the energy absorber when extended by a fall
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have no part of the system come into contact with anything that could affect the safe use of the system
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only be used by a person trained in the safe and correct use of the system
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have written safe rescue procedures
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not to be used if a component of the system shows evidence of wear or weakness to an extent that may affect the system's safety
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be inspected by a competent person at least every 6 months (a written record of the inspection must be obtained)
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not be used after a fall unless its manufacturer or a competent person has inspected it and decided that it is fit for safe use
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not be used by a person working alone.
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2
Quality Requirements
2.0 Introduction
The term Quality Assurance means that something is measured against a standard. The assurance aspect of this is that the standard should be met constantly and with little variation. To be competitive with the painting and decorating industry you need to maintain a standard that the client anticipates for a professional. Regardless of whether you are competing for an employment position or trying to tender a quote for a contract, quality requirements are something that you need to have a firm grasp of. In this section we are going to look at: Quality requirements of a painter & decorator. The industry sectors of a painter and decorator as these will impact on the standards required by the client and the expectations of a quality outcome within the industry. Heritage restorations, clients requiring heritage restoration expect careful planning and research to maintain a quality standard that meets the needs of heritage restoration. The responsibilities of an applicator are also discussed in relations to quality concepts. Workplace communication has a direct bearing on the standards being maintained in the workplace of a painter and decorator. Planning and organising our work place to work effectively also has a significant impact on the quality of our work.
2.1 Quality Requirements
Construction companies that sub-contract to contractors have expectations of quality work set out in their contracts with them. This covers the quality of the materials, as well as the quality of the work and how it’s done.
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There are organisations and authorities which set and document standards. Some that you may come across include: •
workplace Standard Operating Procedures (SOP’s)
•
site safety plan
•
company quality assurance policy and risk management strategies
•
International Standards Organisation (ISO standards)
•
Environment Protection Authority (EPA)
•
Australian Standards.
•
Work Method Statements or Job Safety Analysis (JSA)
The products you use should have a Quality Assurance sticker or Water Mark applied to them. This is your guarantee that a product meets international as well as national standards. The quality requirements of a professional painter and decorator have a strong bearing on a nation’s productivity and economical strength. That may seem like a very strong statement but consider! What is the cost of: •
a building needing to be demolished due to concrete cancer as a result of the painter not applying a correct film thickness to the substrate
•
of corrosion to valuable infrastructure due to incorrect application of coating systems and lack of surface preparation
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timber rot on a building because of incorrect paint coating system
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an investment not selling because of the lack of aesthetic appeal due to a bad paint job?
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Have a look at this photo below, how would you feel if you invested a huge amount of money in a property to end up with a fish like this?
This could have been avoided if the correct paint system was used in the first place! You now have an opportunity to demonstrate what a painter that works to a quality standard is capable of, are you ready for the challenge!
2.2 Painting & Decorating Industry Sectors
The Painting and Decorating Industry can be broken into four main categories: •
New work
•
Repaints
•
Decorative
•
Wallpaper
There are a number of sectors within the industry as well some of these sectors would be: •
Residential work
•
Non-residential or commercial work
•
Industrial Coatings
•
Heritage restoration
•
Maintenance painting
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2.3 Heritage Restoration
Heritage paints attempt to replicate the heritage colours, they also attempt to replicate the texture and reflective values of the original products. This presents some difficulties as many of these original products contained ingredients that are no longer available. Any paints used before 1920 included naturally occurring resins, variations in colour, texture and reflectivity were common, notably bec because ause of inherent variability in materials and processing techniques. Variations in resin supplies, colour availability and personal intervention by the painter make exact replication of original heritage paints, using modern methods and materials, very di difficult. Heritage restoration also includes identifying and restoring decorative paint finishes, stencilling and wallpaper.
By examining old photos, news paper articles and collecting artefacts on the site such as shown above a heritage restorer can reconstruct and replicate a heritage finish. The samples of photos, newspaper articles and artefacts you see above are just some of the resources used to restore a heritage building in Sydney NSW, Australia. The restoration can be seen in the following p photos.
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In the Pacific you will also find many building that could receive heritage restoration. Who will be the professional painters that will undertake such specialist work? Will it be you? The following photos show you some examples of heritage buildings that need restoration in Suva Fiji.
Wallpaper As early as the mid sixteenth century, it was discovered that a design made on paper that was pasted onto a wall in a repeating pattern provided a pleasing backdrop. It was not until the early y years ears of the nineteenth century that a commercial paper rolling machine replaced the painstaking overlapping of sheets of handmade paper to create a sheet of wallpaper. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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Designs were first hand painted, and then eventually hand blocked to create images of a amazing mazing complexity. Realistic murals could use over a hundred blocks, each representing a different colour. Today, existing wallpapers of this calibre are preserved as works of art. Manufacturing wallpaper was incredibly labour intensive. Therefore it is n not ot surprising that few except the very wealthy could afford it in their homes. Most wallpaper was imported from England and France until the mid 1850’s, when factories opened on this side of the Atlantic. The burgeoning middle class Victorians embraced th this is decorating element the way they did every other outward expression of newly acquired wealth – without restraint. Decorating gurus preached about the benefits of wallpaper and soon it embellished every inch of walls that were not covered by woodwork. Objectives jectives To ensure that the interior features are conserved in an appropriate manner. To retain as much of the original fabric as possible. To enhance the understanding of significant interiors through appropriate conservation.
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Decorative Finishes Interior finishes such as original or early wallpaper, paint, stencilling, marbling, wood graining, panelling, plastering and ceramic tile surfaces should be retained and conserved. Where removal of significant decorative treatments is necessary for the conservation of the building, such as to access rising damp, a conservation professional should always be involved. All actions should be fully recorded, including hidden surfaces where they are exposed (e.g. layers of wallpaper or paint).
2.4 Responsibility of Applicators
Paint materials The applicator will ensure that all materials comply with the relevant Australian Standard or other specified Standards nominated in the specifications prepared for the proposed painting work. Surface preparation The applicator will ensure the following: On-site conditions are satisfactory for the preparation of the surfaces to be painted and the premises are suitably equipped with water and power. Surface preparation has been correctly carried out according to the specification or to the amended and initialled alterations that have been agreed to at meetings held between the various parties. All surface preparation and sealing or priming of bare surfaces will be carried out in such a manner and during such weather conditions, that temperature and humidity conditions are acceptable for surface preparation, and that the work performed is not affected by rain, condensation or dew. When surface preparation is completed, precautions will be taken to prevent contamination of the completed prepared surfaces or the sealed or primed surfaces, and that they will not be affected by fumes, toxic materials or other deleterious substances. No damage will be caused to pre-painted surfaces and that other surfaces adjacent to the areas being painted are protected and that no damage occurs to the sealed or primed surfaces, during the ensuring drying period.
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Any damage that may occur to the prepared and sealed or primed surfaces will be made good before proceeding with the work. All coats of sealer or primer, which are to be applied, are of the correct type and are correctly applied. Paint application The applicator will ensure the following: All paints in the paint system are applied to the various surfaces in the correct sequence and in accordance with the prepared specifications and the paint manufacturer’s recommendations, regarding thinning of the paint and paint coverage rates. There is proper paint covering applied to all corners, crannies, thin edges, arrissed surfaces, properly stopped-up cracks, end-grain and other difficult places of paint application. The paint containers carry the label of the correct brand of paint, and the type and the colour of the paint is considered acceptable; all containers are inspected for the presence of leaks or damage, which may cause the contents to deteriorate; and the condition of the paint is checked for such problems as undue settling, thick surface skin, gelling, presence of foreign matter and paint skins. The condition of the paint in the container being used by the paint applicator are will not have undue thinning or adulteration and that the wet or dry film thickness of the coatings are as specified, or equivalent to the paint manufacturer’s spreading rate. Two-pack paint products are correctly measured and mixed according to the paint manufacturer’s instructions and are not used after the expiration of the pot life of the mixed material, as recommended by the manufacturer. Before application of the succeeding coat of paint, each existing coat is given the drying time recommended by the manufacturer. Sufficient paint of the correct type and colour is ‘boxedtogether’, prior to commencement of painting, to ensure that there is enough paint available to complete the whole of the wall or building being painted. All surfaces are dry and condensation related to ensure reduction in temperature does not occur before the surfacedry condition of the paint has been reached. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Any defective work is corrected; the surface preparation performed and the paint system specified for use are correct; the recoating follows precisely the correct paint system nominated, according to the original or amended/initialled and dated specification. All intermediate coats of primer and undercoat are properly scuffed between coats, in order to remove dust pick-up, protruding fibres and coarse particles, and are thoroughly dusted or wiped clean, before the application of the following coatings in the paint system specified. Each coat of paint specified for use in the paint system is in accordance with this Standard, and the following qualities and properties are satisfactory: The paint coatings applied have uniformity of finish, colour, texture, gloss level, opacity, hiding power, paint film thickness and that the proper number of coats of paint have been applied in the correct sequence and in accordance with the specification. The paint is free of application defects and blemishes such as paint runs, paint sags, wrinkling, fatty edges, entrained paint skins, bristles from paint brushes, human hair, dust, bare or starved painted areas, surface cracks, irregular and coarse brush marks, ladders and blistering or other discontinuities.
2.5 Workplace Communication
The following information and illustrations have been drawn from the Basic Building & Construction Skills handbook 3rd edition – published by Pearson Education Australia
The term 'communication' can be applied in three ways. First, it can be applied to the act of communicating. Talking, singing, writing, miming, gesturing, signalling, drawing, sketching, kissing, hugging, hitting, punching or kicking are examples of communication acts. They all carry a message of some kind. Second, communication can also be applied to the message that is being communicated. These messages may be about emotions, feelings, wants, needs, thoughts, ideas, opinions, facts, knowledge, information, warnings, or any one of the many things people need to impart to others. For example, the communication act of talking enthusiastically about your role in a new play, in addition to the information you are conveying, imparts a message that you are excited about performing. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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The communication act of hugging someone imparts the message that you like that person. The communication act of chastising someone imparts the message that you are upset. The communication act of extending your arm forward with your hand flexed upward and palm toward the viewer imparts the message that you want that person to halt. Third, communication can be applied to themeans of communicating. For example, an audio tape on which you have recorded yourself talking about your part in the new play, and which you will send to an interstate friend, is a means of communicating. The accompanying letter that you have written is also a means of communicating. So, too, is the poster that you have drawn to advertise the play a means of communicating. Communication, then, can be understood as the act, the message, or the means of communicating with another person or group of people.
Communication has been successful only when the person or group towards whom the message has been directed (often called the receiver) has understood the message exactly as the person who imparted the message (often called the sender) intended it to be understood. This does not mean that successful communication is the sole responsibility of the originator of the message. On the contrary, successful communicating is also the responsibility of the receiver of the message. Sender and receiver share the responsibility for successful communication.
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All people have different life experiences. These different life experiences shape the character, personality and view of the world of each individual. This will affect the way an individual understands a message from someone else. To be sure the correct message is received, the sender will require 'feedback'. For the sender, feedback may range from a simple request for the receiver to repeat what was said, to an invitation for the receiver to discuss the message. For the receiver, restating the message for the sender is a good check. Communication is a circular procedure that requires checking and rechecking that the message received matches the message sent. Without feedback, failure to communicate is likely. Unfortunately, successful communication is not as simple as the illustration above implies. In reality, there are many impediments to effective communication. These impediments, sometimes called barriers or blocks, can exist in the environment in which the people are communicating; in the system by which they communicate; or in the people who are trying to communicate. Barriers to communication can be conveniently categorised as physical, emotional, psychological or intellectual. Physical barriers in the environment or the workplace, such as loud machinery noise or obscured safety signage, can affect communication. In a telephone or two-way radio communication system, interference can interrupt contact. In people, disabilities such as deafness or failing hearing, and blindness or failing eyesight, can create a barrier to communication. Emotional barriers, of course, occur in people. Emotions such as anger, resentment, frustration, dislike and hatred can get in the way of good communication. The presence of these emotions in the sender can override the content of the message. The presence of these emotions in the receiver can distort the perception of the message. Psychological barriers also occur in people. People's psychological characteristics can influence the communication process. For example, people who as senders are continually aggressive, arrogant, judgemental, manipulative, confrontational or guilt-inducing in their communication behaviour are unlikely to encourage the feedback that is essential to successful communication. Similarly, people who as receivers avoid, make light of, refuse to acknowledge or divert communication messages are avoiding communicating frankly about an issue.
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People also have intellectual barriers to good communication. A person's lack of knowledge can limit his or her effective use of complicated communication systems such as computers. Not understanding the language of signs or instructions might jeopardise a person's safety. Similarly, the lack of a shared language could cause serious misunderstanding between a sender and a receiver. In the workplace, the use of language that is too technical for beginners, or the use of jargon with the uninitiated, can lead to problems. Also, the inability to read technical plans correctly can lead to expensive mistakes. How do we overcome these barriers? First, we must not make the assumption that it is the receiver's responsibility to understand the message we are trying to impart. If it's our message, it is our responsibility to get it across. Second, we must anticipate the possibility of the operation of physical, emotional, psychological or intellectual barriers to communication, and, by imagining ourselves in the shoes of the receiver, try to make sure that our communication avoids these barriers. The communication process The ability to communicate well is an important skill in the building industry. On building sites, poor communication is responsible for injuries, faulty work, and wasting of time and materials. Nobody on a building site wants to be injured, to have to go back and fix a bad job or to waste their time or waste expensive materials. Good communication benefits everyone. Nearly everyone acknowledges the need for good communication, but few people ever think of themselves as being poor communicators. So, if people think they are communicating properly, why are people being injured, and why is faulty work being done, time and materials wasted? This is often because people think that if they can talk, read and write they can communicate. Unfortunately, this is not so. These skills are an important part of being a good communicator, but are not sufficient on their own. Some people who are not expert talkers, readers and writers are excellent communicators. Why? Because they understand that to communicate they must create understanding in the mind of the person with whom they are communicating. No matter how good a talker, or reader or writer you are, you cannot get your message across if you are not communicating.
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Good communicators create understanding. When we are communicating we are creating understanding. If we are not creating understanding we are not communicating. When we communicate we send a message to someone. We are the sender, they are the receiver. If the receiver does not understand the message the way the sender intended it to be understood, the communication has failed. Both sender and receiver have the responsibility for successful communication. They work together to create understanding. They do this by checking that the message received is the same as the message sent. They check by seeking and giving feedback. The sender checks by: •
asking for the message to be repeated;
•
asking questions; or
•
asking for the message to be restated. The receiver checks by:
•
repeating the message;
•
asking questions; or
•
restating the message.
To make sure that you have overcome the barriers to communication, always seek and offer feedback. Spoken language When you are being spoken to face-to-face, always listen actively by: •
looking at the person talking to you;
•
maintaining an attentive posture;
•
showing interest;
•
encouraging the speaker;
•
asking questions;
•
summarising to check your understanding.
Be aware of the barriers to communication that cause misunderstanding and make sure they do not interfere with the message. Always speak with a civil tone and treat people with politeness and respect.
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When you answer a business telephone: •
give a polite greeting;
•
give your company name;
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give your name;
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offer assistance.
•
If you are not able to help the caller:
•
write down the caller's name;
•
write down where the caller is from;
•
write down the caller's number;
•
write down the caller's message;
•
repeat the message to the caller;
•
write down the day, date and time;
•
give a polite farewell;
•
write down your name;
•
deliver the message.
Remember to speak at a moderate pace. The caller may never have spoken to you before, and will need time to tune into your way of speaking.
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Interpreting Written language When you are seeking info information rmation from a document, you can: predict the content from the title or pictures; skim quickly through the document to get a broad idea of the content; Art of clear communication When speaking to someone face face-to-face, face, make sure your message is clear: Use T messages; talk about your thoughts, your feelings, your needs; do not blame or label others; deal with the issue. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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Focus on an outcome, the situation, the problem, a behaviour; do not focus on the person; be consistent; make your body language match your words; do not send conflicting messages; pick your time and place; make sure the other person is not distracted by something else; and seek and offer feedback to check understanding. Always speak with a civil tone and treat people with politeness and respect. If you need to instruct someone, before you begin be certain about what you want the other person to do. Make sure you: •
state the overall goal you require;
•
describe the main steps in the task in a logical order;
•
explain the details of each step slowly;
•
emphasise the critical points;
•
seek and offer feedback to check the other's understanding;
•
and summarise the main steps in the task in a logical order.
Be aware that on a building site you may have to combine spoken language, written language and diagrams to make your instructions clear and understandable to the other person. Communicating in Written language When you write, keep in mind that you are writing to be understood. If your readers fail to get your message you have wasted your time and theirs. Your objective must be to get your message across as clearly and quickly as possible. You do this by writing in plain English. Write your document: •
in a logical order, e.g. from the least important point to the most important point, or vice versa, according to distance, or according to construction sequence;
•
in the active voice, e.g. 'I need more nails', not in the passive voice, 'More nails are needed'; and
•
in short sentences, with one main idea to a paragraph.
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Do not obscure your meaning by using: •
ambiguities; e.g. 'I put the saw in the truck that had been damaged';
•
cliches; e.g. 'Someone spat the dummy' when you mean 'someone became upset', or 'down the track', when you mean 'in the future';
•
tautologies; e.g. 'lineal metres' when you mean 'metres', or 'climb up the ladder' when you mean 'climb the ladder', or 'reverse back the truck' when you mean 'reverse the truck';
•
jargon; e.g. 'Optimise output by maximising labour input' when you mean 'Achieve more by working harder';
•
slang; e.g. 'mud' when you mean 'mortar' or 'helicopter' when you mean 'trowelling machine' or 'bubble stick' when you mean 'spirit level', or 'chippy' when you mean 'carpenter';
Conducting meetings Broadly speaking, there are two ways of conducting these different types of meetings. They may be conducted either formally or informally. Formal meetings Formal meetings are run by elected office bearers called chairperson, secretary and treasurer. Each meeting will follow an agenda. The agenda is prepared by the secretary and sent to the people attending the meeting before the day of the meeting. It will include the time and location of the meeting, as well as what will be discussed and the order in which it will be discussed.
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The meeting will be controlled by the chairperson. When each item is raised by the chairperson it will be discussed, and the meeting will follow a set procedure for making decisions using movers, seconders, speakers for and against the motion, then finally a vote by the meeting for or against the motion. During the meeting the secretary will write the minutes of the meeting, which are summaries of the discussions and the decisions agreed on. The minutes then become the formal record of the meeting.
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Note: These procedures are usually followed only when the items to be discussed affect a lot of people, have legal implications, are required by law, or need to be accurately recorded for future reference. Company meetings, union meetings, occupational health a and safety meetings and special-purpose purpose committee meetings are usually conducted as formal meetings.
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Informal meetings Informal meetings such as tool box meetings, on the other hand, are usually conducted with simple procedures and without the election of office bearers. A group of people will get together to discuss an area of interest. There may not be a formal agenda, but everyone will have a general idea of the focus of the meeting. Someone will probably lead the meeting, and if there are to be a number of meetings group members may take turns at being leader. There will be no set procedures for conducting discussion and making decisions. The success of the meeting will depend on the reasonableness, fairness, self-discipline and depth of the desire to achieve a successful outcome of each of the members of the group. All members will probably take their own notes about issues that affect them directly. During the meeting, individuals may volunteer or be coaxed into undertaking tasks that have been decided on by the group.
2.6 Planning & Organising to Work Effectively
Quality is the outcome of a process, or service that impact their ability to meet or surpass the needs and requirements of a customer. Quality is a measure of excellence; quality defines desirable characteristics of a product, a process, or a service. Quality refers also to the character traits of an individual. One of the qualities of a leader is his or her ability to share the mission and vision in such a way that people want to follow and accomplish the goals. Quality is a perceptual, conditional and somewhat subjective attribute and may be understood differently by different people. Consumers may focus on the specification quality of a product/service, or how it compares to competitors in the marketplace. Producers might measure the conformance quality, or degree to which the product/service was produced correctly.
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3
Calculations & Measurements
3.0 Introduction
In this section you will be introduced to basic measurements and calculations required for estimating materials used in painting & decorating. As a painter you will need to be able to perform the following types of calculations: •
Obtain metric measurements to calculate materials
•
Areas of; circles, squares & rectangles, columns, triangles and trapeziums for material calculations
•
Ratios for two pack materials
•
Ratios for staining, thinning and adding additives to paint
•
Estimations of materials based on area by spread rates
•
Wallpaper and lining paper estimations
•
Film thickness builds
Not that hard really! You won’t have too much problem learning these. Your trainer has access to resources that will assist you if you have any difficulty.
3.1 Measurements
Metric measurements are taken to perform estimations of materials. You are required to measure areas to estimate paint material required for a task. You will find in the specification the spread rate will be calculated on square metres per litre. Square meter measurements are area measurement. The most common way to take measurements for painting and decorating is using a tape measure. The conversion of metric units involves multiplying and dividing by 1000. Millimetres and metres are the basic units of measurement used in the building industry.
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Lengths are described in millimetres, mm. The exception being when dimensions are shown on site plans, which are usually given in metres to two (2) decimal places. Areas are described in metres squared (square metres), m². Volumes are described in metres cubed (cubic metres), m³. There are some basic principles when working with material measurements Lengths of timber, mouldings, sheeting are calculated lengths of multiples of 300 (2100, 2400, 2700, 3000, etc) Things ordered in cubic metres are usually ordered in multiples of .2 of a cubic metre (2.6m3, 2.8m3, 3.0m3, 3.2m3 etc). Wallpaper is usually in rolls of 10 metres with a width of 520 mm. Paint is calculated in spread rates of litres per square metres.
3.2 Calculations
Basic area calculations of shapes Rectangle: Area = Length X Width A = lw Perimeter = 2 X Lengths + 2 X Widths P = 2l + 2w Parallelogram Area = Base X Height a = bh Triangle Area = 1/2 of the base X the height a = 1/2 bh Perimeter = a + b + c
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Trapezoid Perimeter = area + b1 + b2 +c P = a + b1 + b2 + c Circle The distance around the circle is a circumference. The distance across the circle is the diameter (d). The radius (r) is the distance from the centre to a point on the circle. (Pi = 3.14) d = 2r c = πd = 2 πr A = πr2 (π=3.14) Rectangular Solid Volume = Length X Width X Height V = lwh Surface = 2lw + 2lh + 2wh
Prisms Volume = Base X Height v=bh Surface = 2b + Ph (b is the area of the base P is the perimeter of the base) Cylinder Volume = πr2 x height V = πr2 h Surface = 2π radius x height S = 2πrh + 2πr2
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formulas for different shaped bases. Cones Volume = 1/3 πr2 x height V= 1/3 πr2h Surface = πr2 + πrs S = πr2 + πrs =πr2 + πr
Sphere Volume = 4/3 πr3 V = 4/3 πr3 Surface = 4πr2 Once you have determined the surface are of an object then you can calculate the paint by dividing the area by the spread rate which is stated as metres per square litre. For example: How much paint would be required for these objects assuming the paint had a spread rate of 14 litres per m2?
Answer: Base X Height ÷ 2 = area of the triangle 14.7 X 16.5 ÷ 2 = 121.27m2 Area of the triangle ÷ 14litres per m2 = amount of paint per coat. 121.27m2 ÷ 14 = 8.66 litres of paint required.
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Pi X Radius X Radius = area of the circle (let’s say it is a table top) 3.14 X .6 X .6 = 1.13m2 Area of circle ÷ 14litres per m2 = amount of paint per coat. 1.13m2 ÷ 14 = .08 litres of paint required or 80ml of paint.
3.3 Ratios
A "ratio" is just a comparison between two different things. For instance, someone can look at a group of people, count noses, and refer to the "ratio of men to women" in the group. Suppose there are thirty-five people, fifteen of whom are men. Then the ratio of men to women is 15 to 20. Notice that, in the expression "the ratio of men to women", "men" came first. This order is very important, and must be respected: whichever word came first, its number must come first. If the expression had been "the ratio of women to men", then the numbers would have been "20 to 15". Expressing the ratio of men to women as "15 to 20" is expressing the ratio in words. There are two other notations for this "15 to 20" ratio: odds notation: 15 : 20 fractional notation:
15/20
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In the painting industry you will need to have a good understanding of ratios for mixing materials according to specifications. For example mixing two pack paints, adding thinners to material for spraying, adding additives such as mould inhibiters, adding tinters, paint dryers for alkyd paints etc. Let’s say you are only supposed to thin your paint up to 10%. How much thinners would you need if you were to paint with one litre of paint? 10% of 1000ml (1 litre) = 100ml of thinners in a calculator you would type 1000 X 10 then hit the percentage bottom or you could type 1000 ÷ 100 X 10 = But what if you were told that you could only thin 1 part thinners to every 10 parts paint? Well first you would need to total all the parts 1 part thinners and 10 parts paint add up to 11 parts. Then get the total amount of paint required and divide that by the total parts. 1000ml ÷ 11 parts = 90.9 ml each part 90.9ml = thinners 909ml of paint Here is an example of two pack paint ratios Let’s say we have to paint a floor here are the details: Floor area is 36m2 Spread rate of the paint is 12m2 per litre Two coats are required You can only thin the paint by 10% The ratio is 3:1 (so that would mean 3 parts A to one part B) How much of part A and Part B will be required for each coat? Area of floor ÷ spread rate of paint = amount of paint required for each coat. 36 ÷ 12 = 3 litres of paint per coat so you will need 6 litres of paint for two coats.
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Paint is only purchased in – 1ltr, 4ltr, 10ltr, 20ltr lots often it is cheaper to buy a larger can of paint then to buy three smaller cans of paint so you would probably by a 10ltr can and keep some for future jobs or touch up if required. Paint required (3ltr you will need to calculate in ml though so it would be 3000ml)÷ total parts (3 parts A plus 1 part B)= amount of material per part 3000 ÷ 4 = 750ml Part A = 2250ml (3 X 750ml) Part B = 750ml Thinners would be 10% of material required 3000 X 10% = 300ml of thinners per coat If you have any trouble understanding this please speak to your trainer.
3.4 Wallpaper & Lining paper
Wallpaper usually comes in standard rolls of 10 metres X 500mm (.5m)wide. For simplicity we will use these measurements. Wallpaper is hung down the wall so the calculation is as follows per wall. (Wallpaper should be calculated per wall where possible).
To work out the amount of wallpaper you need, you need to know three facts: the perimeter of the room the height of the room the size of the roll of wallpaper to be used. Once you have this basic information, you need to follow these steps: Divide the perimeter of the room by the width of the roll to find out how many ‘drops’ you’ll need. Divide the length of one roll by the height of the room to work out how many drops you can cut from one roll.
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Divide the number of drops needed by the number of drops that can be cut from one roll to find out the number of rolls you need. Here’s an example! Using a standard roll of wallpaper, calculate how much paper you’d need for the following room plan. The room is
Note: The measurements shown on this plan are in metres. Find the perimeter: 5 + 4 + 4 + 4 = 18m Divide the perimeter by the width of the roll: 18 ÷ .5 = 36 drops Divide the length of the roll by the height of the room to find the number of drops available from each roll: 10 ÷ 2.6 = 3.8 drops drops.. (This means that only 3 full drops can be cut from one roll.) Divide the drops required by the dr drops ops available per roll: 36 (drops required) ÷ 3 (drops per roll) = 12 rolls. rolls So! The number of rolls of wallpaper required for the plan is 12! Lining paper is as follows:
Divide the height of the room by the width of the roll to find out how many ‘drops’ you’ll need. Divide the length of one roll by the parameter of the room to work out how many drops you can cut from one roll. Divide the number of drops needed by the number of drops that can be cut from one roll to find out the number of rolls you need.
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Using a standard roll of lining paper, calculate how much paper you’d need for the following room plan. The room is
Note: The measurements shown on this plan are in metres. Find the perimeter: 5 + 4 + 4 + 4 = 18m Divide the height of the wall by the width of the roll: 2.6 ÷ .5 = 5.2 drops Divide the length of the roll by the parameter of the room to find the number of drops available from each roll: 10 ÷ 18 = .55 drops.. (This means that .55 of the parameter of the wall can be cut from one roll.) Div Divide ide the drops required by the drops available per roll: 5.2 (drops required) ÷ .55 (drops per roll) = 9 rolls. So! The number of rolls of lining paper required for the plan is 99!
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4
Plans & Specifications
4.0 Introduction
As a Painter & Decorator you will at times be required to estimate materials and give quotes using a set of plans. You will also at times need to interpret specifications. Specifications will include information about surface preparation requirements, material selection, safety and environmental information.
4.1 Scales, Key, Contours, Symbols & Abb reviations
Title Blocks Title blocks contain important information to do with the project such as: Client Project Location Drawn by Checked by Issue or revision code Scale Date Project Number Drawing Number Title Blocks are usually found in the bottom right hand corner of the plan, and could be vertical or horizontal.
Scales Scales represent the ratio of the size of the drawing. This means that if it is a scale of 1:100 then every millimetre on a ruler would equal 100 millimetres. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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Site plans are usually drawn to 1:200 to 1:100 Elevations & Floor plans are normally 1:100 to 1:50 Dimensions A dimension is a numerical note which describes the physical size of an object on a drawing and is usually shown in millimetres.
Key contours Contour lines establish the rise and fall on the property.
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Symbols
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Abbreviations
4.2 Specifications
4.3 Types of Drawings
Each trade has specifications that will be provided with a working set of drawings. For a painter and decorator the specifications required would be as follows: •
The coatings system
•
The colour scheme
•
The profiles such as texture coatings
There are many types of drawings and details. In this section we will focus on the main drawings that a painter and decorator would be interested in. Site Plans The site plan is a vertical plan view of the building site or allotment. It identifies the location, shape, size and orientation of the construction site, and the position of the building or buildings on the site.
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Using a site plan a painter can determine where the most environmetaly safe place is to clean up tools. It can also give information that may assist in determining the type of scaffold required. Floor plans This plan usually gives more information than any other part of the working drawing. The Floor plan shows: •
the overall shape and size of the project
•
the dimensions of individual rooms, patios, verandas etc
•
the thickness of the walls, external and internal
•
the roof outline, position of hanging and strutting beams if applicable
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A floor plan is very important for a painter. Using the floor plan a painter can calculate the materials and labour required for the project. Used with the specifications the floor plan can assist the painter to identify feature walls and architectural features that need specific applications. Elevations Elevations provide important information that can not be seen in a floor plan. As with the floor plan the painter will be able to identify identi key architectural features such as doors, gutters and fascias as well as the outside skin. Used with the specifications the painters will be able to apply the coating system correctly as specified.
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Sectional elevation The sectional elevation will indicate to the painter the ceiling heights.
Sectional Details Sectional details are very useful in determining the type of lining used on the interior and exterior walls.
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5
Industry Terminology
5.0 Introduction
The Australian Standards 2310 provide definitions of trade terminology for the painting & decorating industry. Definitions in the AS/NZS 2310 include terms dealing with paint types, paint materials, paint characteristics, paint defects, the application of paints and other relevant aspects of paint technology. The objective of the Standard is to provide a better understanding of the terminology used in the paint industry, for the use of those involved in the manufacture, supply, purchase and use of paint, and those involved in the writing of Standards for paints and the framing of painting specifications.
5.1 Glossary of terms
ABRASION RESISTANCE: Resistance to being worn away by rubbing or friction; related more to toughness than to hardness. A necessary quality for floor finishes, enamels and varnishes. ABRASIVE: Used for wearing away a surface by rubbing. Examples are powdered pumice, rottenstone, sandpaper, sandpaper, steel wool. ADHESION: The ability of a coating to stick to a surface. AEROSOL: A product feature that uses compressed gas to spray the product from its container. AIRLESS SPRAY: A spray that increases the fluid pressure of paint by means of a pump that causes atomization with air, resulting in higher film build and little or no over-spray. ALKALI: A substance such as lye, soda or lime that can be highly destructive to paint films. ALKYD: Synthetic resin modified with oil for good adhesion to a clean surface and good gloss, colour retention and flexibility. Slow drying. ALLIGATORING: Condition of paint film where surface is cracked and develops an appearance similar to alligator skin.
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ALUMINUM PAINT: A paint that includes aluminum particles and gives a metallic finish when dried. APLLICATION RATE: The quantity of a coating material that is required to produce, under defined working conditions, a dry film of a given thickness on unit area. ANCHORING: Mechanical bonding of a coating to a rough surface as contrasted with adhesion, which is chemical bonding. ANTI-CORROSIVE PAINT: Metal paint designed to inhibit corrosion. Applied directly to metal. ANTI CONDISATION PAINT: A coating containing cork dust or vermiculite, put on pipes as insulation and to absorb moisture. It has little effect on really heavy condensation, which needs lagging as well as a vapour barrier and good ventilation. ANTIQUE FINISH: A finish usually applied to furniture or woodwork to give the appearance of age. BACK PRIMED: When a coat of paint is applied to the back of woodwork and exterior siding to prevent moisture from entering the wood and causing the grain to swell. BAGGING: Application of a thin layer of cement-based coating by wiping with hessian or similar material, usually to brickwork or concrete to provide a characteristic uneven, textured finish. BENZENE: Powerful but highly toxic and flammable solvent, usually restricted to spray application. BENZINE: Often used as a lacquer dilutent. Highly volatile and a fire hazard in shipping and storing. BINDER: Film-forming ingredient in paint that binds the pigment particles together. BIOCIDE: Additive intended to prevent attack by any harmful organism in a coating material or the film thereof. BLEACHING: The process of restoring discoloured or stained wood to its normal colour or making it lighter. BLEEDING: Undercoat staining through the topcoat. BLISTERING: The formation of bubbles or pimples on the painted surface caused by moisture in the wood by painting before the previous coat has dried thoroughly or by excessive heat or grease under the paint.
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BLOCKING: The unwanted adhesion between two painted surfaces, one of which at least has been coated, when the articles are left in contact under load after a given drying period. BLUSHING: A gloss film turning flat or a clear lacquer turning white, usually caused by moisture condensation during the drying process. BODY: The thickness or thinness of a liquid paint. BOXING: Mixing paint by pouring from one container to another several times to ensure thorough mixing. BREATHE: The ability of a paint film to permit the passage of moisture vapor without causing blistering, cracking, or peeling. BRIDGING: Ability of paint to span small gaps or cracks through its cohesion and elastic qualities. BRISTLE: The working part of a brush containing natural bristles (usually hog hair) or artificial bristles (nylon or polyester). BRUSHABILITY: The ability or ease with which paint can be brushed. BRUSH MARKS: Marks of brush that remain in the dried paint film. BRUSH-OUT: A technique sometimes used to influence a large sale that consists of brushing out a sample of paint onto a slab of wood or other material so the customer can see how the finished job will look. BUBBLES: Air bubbles in a drying paint film caused by excessive brushing during application or by over vigorous mixing that results in air trapment. BUILD: Thickness or depth of a paint film. BURNING IN: Repairing a finish by melting stick shellac into the damaged places by using a heated knife blade or iron. BURNISHING: Shiny or lustrous spots on a paint surface caused by rubbing. CARBONATION: The reaction of atmospheric CO2 with alkaline materials such as cement, lime and plaster.
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CATALYST: A substance whose presence increases the rate of a chemical reaction. In some cases the catalyst functions by being consumed and regenerated; in other cases the catalyst seems not to enter the reaction and functions by surface characteristics of some kind. A negative catalyst (inhibitor) slows down a chemical reaction. CISSING: A defect caused by the contraction of a wet paint film from a surface leaving small circular areas uncoated or of low film build (see also crawling). COLORANT: Concentrated colour that can be added to paints to make a specific colour. COLORFAST: Fade resistant. COLOR UNIFORMITY: Ability of a coating to maintain a uniform or consistent colour across its entire surface, particularly during the weathering process. CONTACT CEMENT: Completely non-staining cement. Ideal for applying wall paneling and for covering counters, cabinets and table tops with both porous and non-porous surfacing materials ranging from linoleum to plastic laminates. COPPER STAINING: Usually caused by corrosion of copper screens, gutters or downspouts washing down on painted surfaces. Can be prevented by painting or varnishing the copper. COVERAGE: The area over which a given amount of paint will spread and hide the previous surface. (Usually expressed in square feet per gallon). CRACKING: The type of paint failure characterized by breaks in irregular lines wide enough to expose the underlying surface. CRAWLING: Varnish defect in which poor adhesion of varnish to surface in some spots causes it to gather up in globs. CRAZING: Small, interlacing cracks on surface of finish. CREOSOTE: A type of liquid coating made from coal tar that is used as a wood preservative. It should not be used on wood that will be painted later. CURING: Final conversion or drying or a coating material.
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CUSTOM COLOUR: Special colours made by adding colorant to paint or by intermixing colours, which permits the retailer to match a colour selected by the consumer. CUTTING IN: Careful painting of an edge such as wall colour at the ceiling line or at the edge of woodwork. CALCIMINE: A water-thinned paint composed essentially of calcium carbonate or clay glue. CAMEL HAIR: Trade name for tail hair from various types of Russian squirrels. Used for sign writer, lacquering brushings and lettering quills. CATALYST: An ingredient that speeds up a chemical reaction; sometimes used in two component paint systems. CAULKING COMPOUND: A semidrying or slow drying plastic material used to seal joints or fill crevices around windows, chimneys. CHALKING: The formation of a loose powder or the surface of paint after exposure to the elements. CHECKING: A kind of paint failure in which many small cracks appear in the surface of the paint. CLEAR COATING: A transparent protective and/or decorative film. COALESCING: The settling or drying of an emulsion paint as the water evaporates. COATING: paint, varnish, lacquer or other finish used to create a protective and/or decorative layer. COHESION: Attraction of molecules within a coating (how it holds together). DISTRESSING: Treatment of furniture, usually in the process of being antiqued, in order to make it appear older than it is. Consists of marring the surface or applying specks of glaze before varnishing. DRAG: The resistance encountered when paint is spread by contact application methods. DRIER: A paint ingredient that aids the drying or hardening of the film. DRY DUST FREE: That stage of drying when particles of dust that settle upon the surface do not stick to the paint film.
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DRY TACK FREE: That stage of drying when the paint no longer feels sticky or tacky when lightly touched. DRY TO HANDLE: That stage of drying when a paint film has hardened sufficiently so the object or surface painted may be used without marring. DRY TO RECOAT: That stage of drying when the next coat can be applied. DRY TO SAND: That stage of drying when a paint film can be sanded without the sandpaper sticking or clogging. DURABILITY: The ability of paint to last or hold up well against the destructive agents such as weather, sunlight, detergents, air pollution, abrasion or marring. DYE, DYESTUFF: A coloured material used just to dye or change colour with little or no hiding of the underlying surface. EFFLORESCENCE: A deposit of salts that remain on the surface of masonry, brick or plaster when water has evaporated. EGGSHELL FINISH: The degree of gloss between a flat and gloss finish. EMULSION PAINT: Paint in which particles are suspended in water or oil with the aid of an emulsifier as in latex paint. ENAMEL: Broad classification paints that dry to a hard finish. They may be flat, gloss or semi-gloss. EPOXY: Clear finish having excellent adhesion qualities; extremely abrasion and chemical resistant. Epoxies are alcohol proof and very water-resistant. EROSION: The wearing away of a paint film caused by exposure to the weather. ETCH: Surface preparation by chemical means to improve the adhesion of coating. EXTENDER: Inexpensive and inert pigment added to paint for bulk and to lower costs. EXTERIOR: The outside surfaces of a structure. EXUDATION: The emergence, on the surface of a film, of one or more of the liquid constituents.
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FLAT APPLICATOR: A rectangular shaped flat pad with an attached handle that is used to paint shingles, shakes and other special surfaces and areas. FLEXIBILITY: Ability of a coating to expand and contract during temperature changes. FLOATING: Separation of pigment colours on the surface of applied paint. FLOW: The ability of a coating to level out and spread into a smooth film, paints that have a good flow usually level out uniformly and exhibit few brush or roller marks. FUNGICIDE: An agent the helps prevent mold or mildew growth on paint. FADING: The loss of colour due to exposure to light, heat or weathering. FEATHER SANDING: Tapering the edge of dried paint film with sandpaper. FERRULE: The metal band that connects the handle and stock of a paintbrush. FILLER: A product used to fill the pores of wood before applying a prime of finish coat. FILLER STRIPS: Strips made from specially treated wood, metal. Fibre or plastic in the centre of a paintbrush, creating a reservoir of paint, thereby greatly increasing the paint carrying capacity. FILM: Layer or coat of paint or other finish. FISH EYES: The presence of craters in a coat each having a small particle of impurity in the centre. FINISH COAT: Last coat of paint or other finish. FLAKING: A form of paint failure characterized by the detachment of small pieces of the film from the surface of previous coat of paint. Cracking or blistering usually precedes it. FLASH POINT: The temperature at which a coating or solvent will ignite. FLAT: A paint surface that scatters or absorbs the light falling on it so as to be substantially free from gloss or sheen.
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GALVANIZED: A thin coating of zinc that covers iron or steel to prevent rust. GELLING: 1 The deterioration of a coating material by irreversible change, partial or complete, to an insoluble gel unworkable even by the addition of solvent. NOTE: This is often termed livering, in the early stages of deterioration. 2 The reversible formation, usually intentional, of a gel-like condition that reverts to a useable state by the application of forces such as stirring or brushing. GLAZE: A term used to describe several types of finishing materials. 1. Glazing putty is of a creamy consistency and is applied to fill imperfections in the surface. 2. A glazing stain is a pigmented stain applied over a stained, filled or painted surface to soften or blend the original colour without obscuring it. 3. A glaze coat is a clear finish applied over previously coated surfaces to create a gloss finish. GLAZING COMPOUND: putty used to set glass in window frames and to fill nail holes and cracks. GLOSS: lustre or shininess of paints and coatings are generally classified as flat, semi-gloss, or gloss; the latter has the higher reflecting ability. GLOSS METER: A standard scale for measuring the shininess or light reflectance of paint. Different brands with the same description such as semi-gloss or flat may have quite different ratings on the gloss meter. GRAIN RAISING: Swelling and standing up of the wood grain caused by absorbed water and solvents. GRAINING: Simulating the grain of wood by means of specially prepared colours or stains and the use of graining tools or special brushing techniques. GROUND COAT: The base coat in an antiquing system that is applied before the graining colours, glazing or other finish coat. HARDBOARD: Reconstituted natural wood, fabricated by reducing natural wood to fibres and then pressing the fibres together into panels of various thickness'.
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HARDNESS: The ability of a paint film to resist denting, scratching or marring. HIDING POWER: The ability of a paint to hide the previous surface or colour. HOLDOUT: The ability of a paint film to dry to its normal finish on a somewhat absorptive surface. HOLIDAYS: Voids in the dried paint film. HOT SPOTS: Lime spots, which are not completely cured and bleed through the coating on a plastered wall. IMPINGEMENT: INHIBITOR: Material such as primer used to retard rusting or corrosion. INTERCOAT ADHESION: The adhesion between two coats of paint. INTERIOR: The inside surfaces of a structure. INTERMEDIATE COAT: The coating between the primer and finish often called a barrier coat. JOINT CEMENT: Cement used for drywall construction; also used as a bedding compound for joint tape and as filler for nail holes. JOINT TAPE: Special paper or paper-faced cotton tape used over joints between wallboard to conceal the joint and provide a smooth surface for painting. KALSOMINE: See Calcimine. LACQUER: A fast-drying clear pigmented coating that dries by solvent evaporation. LAP: To lay or place one coat so its edge extends over and covers the edge of a previous coat, causing an increased film thickness. LATEX: A water-thinned paint, such as a polyvinyl acetate, styrene butadiene or acrylic. LAYING OFF: LEVELING: Ability of a film to flow out free from ripples pockmarks and brush marks after application. LIFTING: The softening and penetration of a previous film by solvents in the paint being applied over it, resulting in raising and wrinkling. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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LIGHTFASTNESS: No loss of colour due to exposure to light, heat or weathering. LIVERING: 1 Early stage of gelling. 2 Thickening of a paint material caused by a chemical reaction between the pigment and binder. LINSEED OIL: A drying oil used in paint, varnish and lacquer. MARINE VARNISH: Varnish specially designed for immersion in water and exposure to marine atmosphere. MASKING: Temporary covering of areas not to be painted. MASKING TAPE: A strip of paper or cloth similar to adhesive tape, which can be easily removed, used to temporarily cover areas that are not to be painted. MASTIC: A heavy-bodied paste like coating of high build often applied with a trowel. MEMBRANE: A high or ultra-high-build coating usually intended to provide moisture or vapour barrier, or to mask imperfections in the substrate. METALLICS: A class of paints that include metal flakes in their composition. MILDEW RESISTANCE: The ability of a coating to resist the growth of moulds and mildew. Mildew is particularly prevalent in moist, humid and warm climates. MILDEWCIDE: An agent that helps prevents moulds or mildew growth on paint. MINERAL SPIRITS: Paint thinners or solvents derived from petroleum. MUD CRACKING: 1 Visible, irregular cracking or checking in thick films of paint caused by shrinkage tension during drying. 2 The formation of deep cracks during drying, occurring primarily with highly pigmented paints applied in thick layers on porous substrates. NAILHEAD RUSTING: Rust from iron nails that penetrate or bleed through the coating and stain the surrounding areas.
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NAP: The length of fibres in a paint roller covers. NONVOLATILE: The portion of paint left after the solvent evaporates; sometimes called the solids content. OIL STAINS: There are two types of oil stains, penetrating and non-penetrating. Penetrating oil stains contain dyes and resins that penetrate the surface; non-penetrating oil stains contain larger amounts of pigments and are usually opaque or transparent. OPACITY: The ability of a paint to hide the previous surface or colour. OPAQUE COATING: A coating that hides the previous surface coating. ORANGE PEEL: Film having the roughness of an orange due to poor roller or spray application. PAINT GAUGE: Instrument for measuring the thickness of paint film. PAINT REMOVER: A compound that softens old paint or varnish and permits scraping off the loosened material. PATCHING PLASTER: A special plaster made for repairing plaster walls. PEELING: Detachment of a dried paint film in relatively large pieces, usually caused by moisture or grease under the painted surface. PIGMENTS: Paint ingredients mainly used to impart colour and hiding power. PIHNOLE: Very small holes in paint film, usually not deep enough to show undercoat. PLASTER OF PARIS: A quick setting, pure white powder, used to set bathroom wall fixtures such as towel racks or used by craft groups for pouring moulds and making plaster objects. POLYURETHANE: Wide range of coatings, ranging from hard gloss enamels to soft flexible coatings. Good to very good adhesion, hardness, flexibility and resistance. Surface preparation critical. POLYVINYL ACETATE: A synthetic resin largely used as a vehicle for many latex paints. Often referred to as PVA. POT LIFE: Amount of time after mixing a two-part paint system during which it can be applied.
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PRIME COAT OR PRIMER: The first coat or undercoat that helps bind the topcoat to the substrate. PROPELLANT: The gas used to expel materials from aerosol containers. PUTTY: Dough like mixture of pigment and oil used to set glass in window frames and to fill nail holes and cracks. REMOVERS: Substances used to soften old varnish or paint so they may be removed easily. RESIN: A natural or synthetic material that is the main ingredient of paint and that binds ingredients together. It also aids adhesion to the surface. ROLLER: A paint application tool having a revolving cylinder covered with lambs-wool, fabric, foamed plastic or other material. ROPINESS: Paint dries with a stringy look because it did not flow evenly onto the surface. RUNS: Blemished film caused by excessive flow of coating. RUST PREVENTATIVE PAINT OR PRIMER: The first coat of paint applied directly to iron or steel structures to slow down or prevent rust. SAGS: Excessive flow, causing runs or sagging in paint film during application. Usually caused by applying too heavy a coat of paint or thinning too much. SAL SODA: Crystallized sodium carbonate. It is used for making cleaning solutions to remove grease and grime from old painted surfaces. SAND FINISH: Rough finish plaster wall. SANDING SURFACES: A heavily pigmented finishing material used for building the surface to a smooth condition. It is sanded after drying. SATIN FINISH: See Semi-Gloss SCRUBBABILITY: The ability of a paint film to withstand scrubbing and cleaning with water, soap and other household cleaning agents. SEALER: A thin liquid applied to seal a surface, to prevent previous paint from bleeding through from the surface or to prevent undue absorption of the topcoat into the substrate. SEEDS: Small, undesirable particles or granules other than dust found in paint, varnish or lacquer.
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SELF-CLEANING: Controlled chalking of a paint film so dirt does not adhere to the surface. SEMI-GLOSS: Having a lustre between full and flat. SEMI-TRANSPARENT: A degree of hiding greater than transparent but less than opaque. SETTLING: Paint separation in which pigments accumulate at the bottom of the container. SET UP: A film that has dried so that it is firm is said to have "set up". SHAKE PAINTER: A rectangular-shaped flat pad with an attached handle that is used to paint shingles, shakes and other special surfaces and areas. SHEEN: The degree of lustre of a dried paint film. SHEEN UNIFORMITY: The even distribution of lustre over the entire surface of an applied finish. SHELLAC: Derived from a resinous substance called Lac. Used as a sealer and finish for floors, for sealing knots and other purposes. A natural resin, usually in the form of thin flakes. SILICONE: See Resin. SKIN: Tough covering that forms on paints if container is not tightly sealed. SOLIDS: See Non-volatile. SOLVENT: The volatile part of paint composition that evaporates during drying. SPACKLING COMPOUND: A material used as crack filler for preparing surfaces before painting. SPAR VARNISH: A very durable varnish designed for service on exterior surfaces. SPATTER: Small particles or drips of liquid paint thrown or expelled when applying paint. SPOT PRIMING: A method of protecting localized spots. The only areas primed are those that require additional protection due to rusting or peeling of the former coat. SPRAYING: A method of application in which the coating material is broken up into a fine mist that is directed onto the surface to be coated. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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SPREADING RATE: The area to which paint can be spread; usually expressed as square feet per gallon. STAIN: A solution or suspension of colouring matter in a vehicle designed primarily to be applied to create colour effects rather than to form a protective coating. A transparent or semi-opaque coating that colours without completely obscuring the grain of the surface. STIPPLING: A finish made by using a stippling brush or roller stippler or a newly painted surface before the paint is dry. STREAKING: The irregular occurrence of lines or streaks of various lengths and colours in an applied film; usually caused by some form of contamination. STRIP: Removal of old finishes with paint removers. STYRENE-BUTADIENE: See Resin. SUBSTRATE: Surface to be painted. SURFACE TENSION: The property of a coating that makes it tend to shrink when applied. TACK RAG: A piece of loosely woven cloth that has been dipped into varnish oil and wrung out. When it becomes tacky or sticky, it is used to wipe a surface to remove particles of dust. TACKY: Sticky condition of coating during drying, between wet and dry-to-touch stage. TEXTURE: The roughness or irregularity of a surface. TEXTURE PAINT: Paint that can be manipulated by brush, roller, trowel or other tool to produce various effects. THINNERS: Solvents used to thin coatings. THIXOTROPY: The property of a material that causes it to change from a thick, pasty consistency to a fluid consistency upon agitation, brushing or rolling. TINT BASE: The basic paint in a custom colour system to which colorants are added. TONER: Pigmented lacquer sealer that is applied by spray. Toners provide colour and make the surface appear more even. TOUCH UP: The ability of a coating film to be spot repaired (usually within a few months of initial painting) without showing colour or gloss differences.
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TURPENTINE: A colourless liquid, which is used as a thinner for oil paints and varnishes, distilled from the products of the pine tree. UNDERCOAT: A primer or intermediate coating before the finish coating. VANADIUM STADIUM: Unsightly staining, usually redbrown in appearance, that develops staining on light coloured bricks containing traces of vanadium compounds that bleed through any applied paint film. VARNISH: Transparent liquid that dries on exposure to air to give a decorative and protective and protective coating when applied as a thin film. VARNISH STAIN: Varnishes coloured with a dye and without the same power of penetrations as the true stains, leaving a coloured coating on the surface. VEHICLE: The liquid portion of paint composed mainly of solvents, resins or oils. VINYL: A resin with poor adhesion but good hardness, flexibility and resistance. Used for swimming pools, tank linings and marine equipment. VISCOSITY: The thickness of a coating as related to its ability to flow as a liquid. WASHABILITY: The ability of a paint to be easily cleaned without wearing away during cleaning. WATER EMULSIONS: Mixture of pigment and synthetic resin in water with low solvent emission, low fire hazard and toxicity and good durability and chemical resistance. WATER SPOTTING: A paint appearance defect caused by water droplets. WEATHERING: The effect of exposure to weather on paint films. WET EDGE: Length of time a wall paint can stand and be brushed back in to the next stretch without showing a lap. WITHERING: Withering a loss of gloss is sometimes caused by varnishing open-pore woods without filling pores, use of improper undercoating or applying top coat before undercoat has dried.
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WOOD FILLER: There are two kinds of fillers-paste and liquid. Paste fillers are something like a very thick paint and are composed of some solid powdered substance, usually silica or powdered quartz, mixed with linseed oil or varnish thinned with turpentine or benzene. WRINKLING: Development of ridges and furrows in a paint film when the paint dries. YELLOWING: Development of a yellow colour or cast in white, a pastel, coloured or clear finishes. ZINC CHROMATE: Rust-inhibiting pigment, greenish-yellow in colour that is used with a high-hiding pigment. ZINC OXIDE: Substance used as a white pigment for highhiding power hardness and gloss. Reduces yellowing, increases drying; provides resistance to sulphur fumes and mildew. Used with linseed oil for self-cleaning exterior paints.
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6
Spontaneous Combustion
6.0 Introduction
Combustion or fire is the reaction of three elements brought together. These three elements are: Heat Air Fuel Spontaneous combustion is a fire that starts unexpectedly, in a spontaneous (impulsive, unprompted, unplanned) manner. The Encyclopaedia Britannica defines spontaneous combustion as the outbreak of fire without application of heat from an external source. This combustion can occur when flammable matter like oily rags, damp hay, leaves, or coal is stored in bulk. Spontaneous combustion, sometimes referred to as spontaneous ignition, begins when a combustible object is heated to its ignition temperature by a slow oxidation process. Oxidation is a chemical reaction involving the oxygen in the air around us gradually raising the inside temperature of something (like a pile of rags) to the point at which a fire starts.
6.1 Prevention of Spontaneous Combustion
Your trainer will demonstrate flash point, auto ignition point and combustion using flammable solvents. If this has not taken place please speak to your trainer to have this demonstrated to you. The following are some practical suggestions on how to prevent a fire: Remove unwanted fuel and rubbish Store fuel and combustible materials carefully Use only approve electrical fittings Don’t overload electrical circuits Don’t smoke in the work place Take special care when working with flammable liquids or gases Be careful of oily rages which can ignite with spontaneous
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combustion. Avoid dust hazards many types of dust are highly flammable
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7
Tools, Equipment and Materials
7.0 Introduction
There is a saying that “a tradesman is only as good as his tools� in this section we will consider what tools a trade Painter & Decorator has.
7.1 Brush ware
A brush is made up of 4 basic components:
A. Handle - B. Ferrule - C. Setting - D. Filling Handle Shaped to suit the size and type of brush can be made of plastic but are usually made of hardwood, sealed to make handling and cleaning easier. Setting This is a substance that cements the fibres together at the base. Setting materials are usually rubber or epoxy resin. Ferrule The ferrule is a metal bond that holds the setting and fibres to the handle. The ferrule is usually made from nickel plated steel or copper. The ferrule is fixed to the handle by either: (a) Rivets (nails) through the 'ferrule into the handle, or (b) A seamless ferrule pressed onto the handle.
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It is important not to bang the ferrule against an a object to clear out the water or thinner. This damages the brush by causing it to go out of shape. Filling The "filling" is the fibres used to apply the paint. There are four main types of filling materials: (a) Bristle
(b) Man Man-made fibres
(c) Natura Natural fibres
(d) Mixtures of bristle, hair and fibres.
Bristle This term describes the hair from a pig. Most pig bristle' comes from China, a small quantity produced in Russia Russia. Properties • They are strong and • •
flexible They have a split end that gives a fine soft tip. They have rough edges along the length of the (bristle as illustrated above) that prevents the hairs from lying close together and enables the brush to hold more paint.
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Some brush brushes es have been made especially for use with water based paints using synthetic fibres. Properties • They are long wearing • •
and flexible They are resistant to many chemicals They can be mechanically tapered with split ends but are smooth and cannot hold paint as well as bristles.
NATURAL FIBRES FIBRES.. Obtained from plants and marine grasses. Very few modern paint brushes use natural fibres in their filling Synthetic fibres have been made to replace the natural materials once used. Properties • They have no taper or rough • •
edges They are coarse with very poor flexibility. They are resistant to alkalis (soaps, detergents, etc) and are ideal for washing down.
CARE AND MAINTENANCE OF BRUSHWARE More brushes are destroyed by poor care and maintenance than are worn out in service. Good quality brushes are too expensive to ruin and with care will give satisfactory results for many months. Water based paints Remove paint by washing thoroughly in clean water.
Do not wash brushes with the bristles facing upward and the water running down them. This will cause the bristles to tangle and the paint will settle in the bristles near the handle.
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If necessary, remove any hardened paint carefully with a wire brush.
After washing, spin the brushes to remove traces of dirty water. Spin in an empty container or bucket to contain the spread of water.
Wash the brushes in warm, soapy water. Rinse thoroughly in clean water. Before using a dry brush in water based paint, first wet the bristles to prevent the paint from sticking to the bristles. Oil based paints Brushes used for applying oil oil-based based paints can be kept soft overnight by soaking the bristles in water. Suspend the brushes in water so that the bristles are just covered. If the brushes are to be stored for some time. Wash out thoroughly in solvent to remove traces of paint. Spin to remove all traces of solvent. Wash in soap and water, then rinse clean. Straighten and shape the bristles. Store the brushes laying down flat. Care while using a brush When using brushes, the lif life e of the brush will be prolonged if you:
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Do not poke surfaces with the brush unless you intend to stipple the paint. Poking paint onto a surface causes the brush to fan out. If you are stippling then it would be best to select a brush for this purpose. If I you can’t obtain a proper stipple brush then use worn out older brushed for this purpose.
Do not use a large, flat paintbrush edgeways; This will wear down the corners of the bristles.
Do not apply undue pressure on the brush; this will cause the bristles to wear out in the centre.
Choose the correct size brush for the job; flat large brushes for large areas. Sash cutters for woodwork. Do not leave brushes out of paint for any great length of time, causing the paint to dry in the bristles; avoid poking p the brush at the surface,, the bristles will bend out of shape. •
To maintain the shape of the brushes, the bristles can be set in Vaseline or neat's-foot foot oil prior to laying them down.
•
Do not wash or use a bristle brush in alkaline materials (e.g. Sugar soap) as alkalis can cause the bristles to lose their flexibility and shape.
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Sash Cutters [Sometimes known as "sign cutters") Used mainly for exacting work where neat cutting in is important e.g. painting to sashes, architraves, skirting boards and cornices. Sizes: 25mm, 38mm, 50mm, 63mm and 75mm wide
Wall Brushes (A general general-purpose brush) Used to apply a wide range of coatings to a variety of surfaces Sizes: 25mm, 37mm, 50mm, 75mm and 100mm wide
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Lining Fitches Used with a straight edge to pro produce duce straight lines.
Dusting Brushes Usually made from bristle or nylon, used to remove dust from surfaces that are to be painted.
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Angle Brush – Radiator Brush Used to apply paint to restricted areas such as behind pipes.
7.2 Rollers
The standard roller is made up of an open framed cylinder that rotates on a spindle attached at right angles to a handle. Rollers are available in widths from 80mm up to 460mm. Replaceable covers of various fabric materials fit over the roller frame.
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Roller Covers The covers are made to fit firmly over the roller cylinder and are available in widths to suit the various frames. The surface of the core is covered with either natural or synthetic fibres or "pile" from 6mm up to 40mm long to hold the paint. The type and length of the pile is made to suit the type of paint and surface finish over which the paint is applied.
Double yoke roller frame for larger areas. Types of Roller Covers LAMBS WOOL: (short pile up to 10mm) Makes a good general general-purpose roller, ideal for water and solvent thinned paints on smooth surfaces.
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LAMBS WOOL: (long pile up to 32mm) Used for painting heavily textured surfaces such as brick, concrete and roughcast.
PLASTIC FOAM: (known as estafoam) Designed for the application of gloss and semi-gloss semi enamels on smooth surfaces.
POLYESTER: (10mm standard pile) A cover recommended for water based paints on smooth and semi semi-smooth surfaces.
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TEXTURE ROLLER This is a mesh cover in different types of profiles and p patterns. atterns. These are used to produce a textured finish with heavy textured coatings.
MOHAIR: (6mm standard pile) Has a very short pile and leaves very little texture, is suited for gloss and semi gloss paints on smooth and semi-smooth semi surfaces.
Other types of synthetic roller covers include mixtures of nylon, polyester and acrylic.
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Cleaning rollers used in water water-thinned paints If rollers are to be used again with the same colour and type of paint in the immediate future, immerse them in water. The w water ater covering the rollers prevents the paint from drying. When a change of colour or paint type is required, or when the roller covers are to be stored for any length of time, clean the roller out completely. Rinse the cover under a running tap or in a bucket buc of water to remove all traces of paint. When reasonably clean, spin out the excess water. A roller spinner is manufactured for this purpose.
Do not spin out the roller in the area where you have been painting. Spinning spreads the excess paint and water over a wide area. Clean the roller in an open space. Hold the roller well clear of yourself otherwise you will be spattered, or spin the roller inside a large empty tin or bucket to contain the spread. Repeat the rinsing procedure and spin dry. Clean Cleaning rollers used in solvent-thinned thinned paints: Carefully scrape off the excess paint from the cover with a knife or scraping blade. Pour some clean thinner into a spare roller tray. Work the roller into the thinner to remove the remaining paint.
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Spin out tthe he thinner from the roller. Replace the thinner in the tray with clean thinner and repeat the procedure. Spin the cover dry, Wash the cover in soapy water, rinse and spin dry. Rinse in clean solvent Roller Trays Roller trays and roller buckets are containers containe made to hold the paint and have a ribbed, non non-skid skid sloping bottom for loading the roller. Trays hold about 3 litres of paint and buckets hold up to 15 litres.
Extension Poles Telescopic extension poles can be used with most rollers to allow high ce ceiling iling and wall areas to be rolled without using scaffolding.
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Some telescopic extension poles ban hold brushes and roller handles on a threaded swivel head and have a threaded base for attachment to similar extension poles for extra length.
7.3 Hand Tools
Stopping Knife, Putty or Glazing Knife Usually have one side of the blade straight and the other curved, but can be obtained with a double curved blade. Use: To force putty and stopping materials into small holes and cracks. Also used to angle puttie putties when glazing. Care: If the point becomes worn or burred over, the blade should be reground.
Stripping Knife or Scraper Strong, carbon steel blade must be able to keep a good edge. Use: To remove wallpaper, old paint and loose materials
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Wire Brush Hardened and tempered steel wires in a wooden handle. Use: To remove corrosion from iron and steel and remove loose materials from surfaces before painting.
Filling Blade A thin blade of specially treated metal that is flexible. The blade need not be sharp but must be thin and true without any nicks. Use: To apply filler to opengrain timbers, small holes or indentations in uneven surfaces. DO NOT USE FOR SCRAPING! ––keep these separate from your scraping blades.
Shave Hook The head has a bevelled b cutting edge and is available in three shapes. Use: To scrape paint from mouldings, cornices and ornamental beadings. They are usually used with paint removers or burning off equipment.
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Tungsten Carbide Scrapper A handle with a very heavy duty tungsten carbide replacement blade. These blades are extremely hardwearing but at the same time are brittle they should only be used on timber. Use: for removing paint off timber.
Hacking Knife This is a short stubby tool that is used with a hammer. Use: A tool for removing old putty from a window frame prior to reglazing. Also known as hackinghacking out tool.
Glass cutter These come in a number of types including self lubricating cutters. Use: Cutting glass for window glazing.
Glass pincers A pair of pliers with a flat long mouth. Use: used to snap glass or nibble away at glass when window glazing.
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Caulking Gun Used to deliver oneone component sealants and gap fillers. Use: One-component One sealants are commonly sold in cartridges which are loaded loade into the caulking gun for application. A bead is delivered from the gun and can be pressed into the joint so that it can bond with the materials on both sides, and also be smoothed.
Apart from what is mentioned above a Painter and Decorator will need the following items: Hammer and nail punch – for setting back protruding nails or rusty heads before painting. Screw drivers – for removing and replacing door and window furniture. Spanners – for maintenance of spray equipment and other tools as well as re removing moving fixtures and fittings. Pliers – for removing protruding nails or bits of wire. There is no doubt that there are many other tools that a painter will use use, it would not be possible to list everything you many need.
7.4 Power Tools
Belt Sander This is a sanding machine with a continuous belt of abrasive paper. It maintains a flat very fast sanding action. Use: To sand and level flat timber surfaces and to remove thin coatings from timber.
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Orbital Sander This is an electricity or air driven sander with a rectangular pad onto which abrasive papers arc fixed. The pad moves in a small circular or orbital motion that abrades the surface. Use prepares and smooth timber, metal and previously painted surfaces.
Random Orbital Sander This sander has the motion of an orbital sand but spins as well. It has very low torque so it is not aggressive on a substrate. Use: for removing old paint and smoothing surfaces. Sanding Mouse This is a small orbital sander with a triangle tip. Use: for sanding in hard to reach areas. Heat Gun This tool works much like a hair dryer only it emits much more heat. So much heat that you can easily burn your fingers if you touch the end. Use: Primarily a painter would use this to tool to remove paint. It can be effective for removing lead based paint as it does not create fumes if used correctly. At times it is used for drying paints however care must be taken as it can easily burn the paint or damage the substrate.
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Angle Grinder This tool comes in two main sizes and will have speed of anything from 3000 RPM to 11000 RPM. Use: there is a variety of fittings that a painter could use: Masonry cutting disc – for cutting out concrete around rusted steel Wire brushes – for removing paint and corrosion of steel before repainting. Steel disc – for removing severely corroded steel where repair is needed prior to painting. painting Important information These are probably one of the most dangerous and widely misused tool on any job site. Please Ple note the following safety tips: Receive training before use Wear correct PPE Do not wear loose fitting clothes or Jewry. Make sure the fitting matches the speed of the grinder Keep it dry when using it Make sure you do an inspection before you use it check for any damage to the housing and that the fittings attached correctly
7.5 Abrasives
An abrasive is a hard material used to smooth rough or irregular surfaces. A coated abrasive is a sheet of paper or cloth, which is coated with an abrasive material. The use of abrasives is often referred to as ‘sanding’ or ‘rubbing down’. Surfaces are rubbed down to: Smooth rough surfaces prior to painting, Slightly roughen surfaces that are too smooth to
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provide a ‘key’ or grip for the paint to stick to. Some coated abrasives can also be used with power sanding equipment. Rubbing down surfaces is done either wet or dry: Wet rubbing is carried out by using a waterproof abrasive with a lubricant (usually water) Dry rubbing (or sanding) is carried out by using a coated abrasive without a lubricant Wet Rubbing Advantages of wet rubbing: The use of water means the rubbing is dust free. The water acts as a lubricant and keeps the cutting edge of the abrasive sharp and free of a build up of pigment. Hand held abrasives are best used with a sanding block: •
To enable pressure to be applied evenly,
•
To help level the surface
•
Prevent the edges of a surface becoming rounded.
Wet rubbing should never be carried out with electrical sanding equipment severe electrical shock will occur. Coated abrasives are graded (numbered) which matches the size of abrasive particles used. The particles pass through-sieves which grade them according to their size. Common grades range from 120 [coarse) to 600 (fine). Backing papers are graded according to their thickness or weight. The grades range from A through to E. Two (2) common grades of paper used are Grade ‘A’ which is lightweight and flexible. This paper is used to support finer grades of abrasive particles. Grade ‘E’ a heavyweight and more rigid backing paper. This paper is used to support coarser grades of abrasive particles. Some coated abrasives use a cloth instead of paper as a Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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backing. Glass Paper Natural abrasive materials glued to grade D paper with a water soluble adhesive. GRADES: Strong Coarse Medium Fine A comparatively cheap abrasive. Tends to scratch the surface and clogs quickly with pigment when used on painted surfaces. This type of abrasive is not usually used by the professional painter. Aluminium Oxide This is the most common abrasive used by professional painters and decorators. No doubt the abrasive you will be using your training is aluminium oxide. This abrasive is available in roll form. Different manufacturers have different coloured rolls, e.g. Green, Yellow or Red. All brands use aluminium Oxide; the colour is unimportant and does not denote quality or grade of abrasive. This paper has a number’ of different brand names. They all use Aluminium Oxide as the abrasive. They all are opencoated which means that the abrasive particles are spread out to avoid clogging. They all use zinc salts as a dry lubricant powder, to keep the cutting edge clean. GRADES: 80, 120, 150, 180, 220, 240, 280, 320, 400 This paper is the highest quality dry abrasive paper available. This abrasive can be purchases by the metre, in sheets or in rolls. Garnet Paper Natural garnet open coated to grade ‘D’ paper with a water soluble adhesive. GRADES: 40, 60, 80, 100 A general purpose coated abrasive paper with a very sharp cutting edge. This paper is being replaced with other abrasive due to the cost of the garnet.
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‘Wet & Dry’ (waterproof silicon carbide) Synthetic silicon carbide on a waterproof backing paper. GRADES: 120, 180, 220, 280, 320, 400, 600 (Finer grades are available for automotive finishing) Used with water for abrading all types of previously painted surfaces before painting. Refer to wet rubbing above. Steel wool: Is sometimes used as an abrasive. Steel wool is especially suitable for use on moulded and rounded surfaces. One down sides to this abrasive is the fine metal files that may corrode into the paint unless they are dusted off and removed carefully before applying the paint. Cutting & polishing compounds Used on some coatings to remove dust and to polish surfaces. Scouring pads A woven nylon pad with a mineral abrasive can be green, red or grey. This material is sometimes used with a resin to form an abrasive that can be used on a sanding machine.
7.6 Chemicals
CHEMICALS Chemicals are used more in surface preparation than ever before. The chances are that they will become used even more in the future. When we speak of chemicals we mean specifically the chemicals used in preparation of surfaces. Chemicals can be broken into two groups, Alkalis & Acids. These groups relate to the pH value of the chemical. PH value is the measure of acidity or alkalinity. Ph Value of acids ranges 1 to 7 and alkalis from 7 to 14. PH 7 (seven) is considered neutral.
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Many surfaces which are painted are either Alkaline or Acidic. This means that they are chemically active. Acids and alkalis have the ability to neutralise each other. Therefore a highly alkaline surface can be made chemically neutral by treating it with an acid. Surfaces can be chemically active in their natural form or can become chemically active when they come into contact with chemicals. Chemical preparations provide many acute and chronic hazards. It is important that you be familiar with the Material Safety Data Sheet (MSDS) before using any chemical. Important things to remember: Do not combine chemicals unless you absolutely know if they can be combined Be familiar with all hazards associated with the chemical Wear recommended Personal Protection Equipment (PPE) Be careful that the chemical does not ruin the substrate, always use a small test area first in an inconspicuous location Use chemicals in accord with manufacturers recommendations and specifications Use safe storage practices Use safe work practices Be familiar with the ‘work method statement’ your employer has on the chemical ALKALIS Alkaline Surfaces Examples of surfaces which are alkaline in nature: •
plaster;
•
cement sheeting;
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brick;
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cement based products;
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Examples of how surfaces may become Alkaline in practical use are: •
Timber treated with caustic soda to remove old coatings.
•
Timber surfaces bleached with ammonia.
•
Surfaces washed down with detergents and which have not been rinsed properly.
It is important to remember that strong alkalis will destroy many paint coatings. If using any alkalis dilute them appropriately and ensure that any residue is cleaned off and neutralized prior to painting. Chemicals with the words Soda or Sodium in their name are Alkaline. To neutralize a ph level you can wash an area with a chemical of the opposed ph level. Most often it is only necessary to rinse with water (water is ph neutral) to remove the residue. Tri-Sodium Phosphate (commonly known as sugar soap) Used for cleaning off fats, oils and some stains including mould and mildew. Tri-sodium phosphate is a popular alkaline for surface preparation as it does not leave too much of a residue. Common Detergents These are usually more aggressive then tri-sodium phosphate and can leave an alkaline residue that will have to be removed prior to painting. Be very careful of using these, where possible stick to trisodium phosphate. Sodium Hypochlorite Sodium Hypochlorite is a strong liquid alkaline commonly used as household bleach and for chlorinating pools. You will find Sodium Hypochlorite in many products designed for removal of mould. In surface preparation Sodium Hypochlorite can be used to remove mould and mildew. The advantage of this chemical is its strength, but there are some precautions. •
It will completely eat brushes made from natural fibre
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•
Sodium Hypochlorite when dry forms Sodium Chloride (salt). It is very unsuitable to paint over salt as salt destroys Acrylic, Vinyl and Alkyd paints. Ensure that you wash off the Sodium Hypochlorite solution thoroughly.
•
This product can destroy clothing
•
It is very volatile when mixed with some other chemicals.
•
It can be corrosive to your skin or eyes
Sodium Hydroxide This product is often called Caustic Soda. This product is usually obtained in dry powder form and is mixed with warm or hot water. When mixing caution must be taken as the product can react volatile when it is mixed. It is best to add the powder slowly to the water then the other way around. Sodium hydroxide is very caustic, extremely alkaline and will destroy all biological matter. This makes it very good for cleaning mould, moss and mildew. It is also effective in removing vanadium stain. Again this chemical is very hazardous and cause nasty burns and injuries if not handled properly. It is very important to remember that sodium hydroxide will leave an alkaline residue so it must be rinsed very with plenty of clean water. It may also need a mild acid solution to neutralize it as well. Methylene Chloride This is a very alkaline product used for stripping paint. The actual methylene chloride looks clear and not very viscous like water, but most paint strippers have added cellulose fibres to thicken the methylene chloride up so that it stays on the surface longer. ACIDS Acidic Surfaces Very few surfaces which are commonly painted are naturally acidic with the exception of some types of Red Pine. Surfaces may become acidic in the following ways: •
Through the careless neutralization of alkaline surfaces and the acid etching of surfaces.
•
Acids can be used to chemically neutralize alkaline surfaces and to etch surfaces.
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•
If the acid used is too strong, or if it is not rinsed off as directed, the surface may become acidic through pollution deposited on the surface.
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City and industrial areas often have atmospheres which are highly acidic due to industrial processes giving off sulphurous fumes and other acidic deposits.
•
Cooking fumes in kitchen areas can be acidic and can leave traces of acid salts if condensation occurs.
Acid used in surface preparation Acids are commonly used for preparing surface by etching surface and sometimes conditioning surfaces. There are even acids that bleach stains. Usually chemicals that are Acids will have the word ‘acid’ somewhere in their name. Hydrochloric Acid Hydrochloric Acid is often used for neutralizing masonry surfaces e.g. brickwork, concrete, etc and is useful in etching concreting as it react to the sodium’s (alkaline) contained in the cement. It will attack the surface of the concrete actually eating into it until it neutralizes. If not diluted appropriately it can cause damage to the surface of the concrete. This product can also be combined with Oxalic Acid in rejuvenating timber. Phosphoric Acid Phosphoric Acid is contained in many Primers and Acrylics designed to paint over steel. This is because the Phosphoric Acid etches into the metal and keys the paint in better. It can also be very effective in removing surface rust stains and is said to ‘convert rust’ (there is no evidence that it actually converts anything, but it does turn the rust black and seems to suppress the corrosion for a period). Oxalic Acid Oxalic acid usually is obtained in dry powder form and is mixed with water. Oxalic acid can be used for cleaning down masonry surface and is milder in its reaction with concrete than hydrochloric acid. It is also very effective in bleaching timber and Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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restoring it for staining. Citric Acid Citric acid is very mild and useful for safely neutralizing surface that has been treated with an alkaline. Citric acid can also be used for slowing down the drying of cellulose fillers. Solvents Basically solvents are chemicals that will specifically react against other chemicals and break down there properties. There are many different solvents, some are useful in cleaning, others react with coatings to provide adhesion and some solvents will remove old paint coatings. Many of the products designed for removal of fat and oil are solvent based. Many of the solvents designed for cleaning are made up of common hydrocarbons. Solvent also come in the form of thinners/reducers for reducing the viscosity of the paint.
7.7 Filling & Stopping materials
The terms "stopping and filling" are often used simply to describe the levelling of a surface. The term stopping and filling differ from each other in definition. Stopping: The process of levelling holes or cavities with a material that dries with a minimum of shrinkage. Filling: The process of achieving a smooth surface by applying a paste (filler) with a filling knife or blade. Make sure your equipment is clean. Prepare stopping material to the manufacturer’s instructions. To avoid wastage of materials, mix only sufficient material that can be used within the setting time.
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Fillers "Filling" is a trade term for the filling of fine scratches and small imperfections on surfaces where quality finishes are required. Many "filling" materials if used in deep holes, cracks etc. will shrink and crack when dry and will take a long time to dry thoroughly. Examples of Fillers are: •
Water mixed cellulose fillers
•
Ready mixed oil-based & water base fillers
When preparing surfaces, it is necessary to fill repaired defects and indentations so that they are not seen in the finished job. The process of achieving a smooth surface by applying a paste (filler) with a filling knife or blade. When preparing surfaces, it is necessary to fill repaired defects and indentations so that they are not seen in the finished job. Stoppers "Stopping" is the trade term used for the patching of deep holes and cracks in surfaces. Some examples of stopping materials would be: •
Putty
•
Plaster
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Sand and cement
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Cellulose filler/stopper
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Plastic wood
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Fibreglass
•
Caulking compounds
When applying stopping to timber it is essential to coat the background with primer first. If using a oil base putty without priming the timber first, the oil would be absorbed in the unpainted timber, shrink and eventually fall out.
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The purpose of stopping is to fill any holes, cracks and similar defects such as nail holes, timber cracks or dents in the surface. The stopping should be stiff enough to be applied to the defect without sagging during the setting period, also have enough elasticity to conform to the surface movements due to contraction or expansion. Another form of stopping is caulking. Caulking is a term used to describe the process of sealing joints or seams in various substrates.
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8
Plan & Prepare for Painting & Decorating
8.0 Introduction
When you work on a construction site, you’ll be part of a large team. You may even be part of many teams on the same site. You might be working for a sub-contractor who is one of many companies working on the site at different times, and sometimes all at the same time. You need to become familiar with the work practices and meetings held on the site, follow instructions and observe the signs put up on the site. You’ll also need to become familiar with the emergency procedures in case there is an accident or something serious happens. Talk to your boss or supervisor to become familiar with the expectations of the construction contract, how you’re expected to work and report, and what to do if there’s an emergency. When planning and preparing to apply paint, decorative finishes or wallpaper, you need to identify the tasks you’ll need to carry out to make sure they run smoothly. This includes checking that your work area is safe and hazard free, that you have the correct personal protective equipment and that you select the appropriate tools, equipment and materials and know how to use them safely and effectively Planning and preparing your workplace will include identifying the following: What type of work is to be done? Where is it to be carried out? What materials will be required? What tools and equipment will be required? What is the construction sequence? Will other tradespeople be on site?
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8.1 Prepare work Area
SET UP STORAGE AREA Tidy up the work area Before you start work, make sure you clean up the work area. Remove rubbish and leftover building materials. These can get in your way and be a safety hazard. In addition to cleaning up the work area, you need to do the following: Set up a storage area To ensure the safety of yourself and others and to give yourself the maximum space possible in the actual room you’re going to be working in, you should set up a separate storage area. Make sure that the storage area has good ventilation and light is neither too hot nor too cold is large enough to easily hold all materials and equipment is close to the area you’re actually going to be working in Prepare the storage area by: covering the floor with protective drop sheets (doubled up so that they’re thick) storing materials AWAY from the equipment to prevent any accidents placing all equipment and material so they’re easily accessible Storing any inflammable materials in an area where they can’t easily be tipped over or damaged. Make sure that they are not near any source of heat or naked flame. SET UP WORK AREA Remove / Protect furniture and other items: Remove any furniture and other items that could be damaged or obstruct your ability to work safely and effectively. This includes removing ornaments, pictures, window dressings or any other decorative items. Store furniture and these other items safely in another area.
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If furniture cannot be removed from the room then you should move it into the centre of the area you’ll be working in and cover it to keep it from being damaged. Cover all floor coverings (like carpet, polished floors, tiles, etc.) with drop sheets. Use plastic drop sheets if possible to keep the area as dry as possible as water and old adhesive and size will drip onto the floor as you’re working. Plastic drop sheets are ideal for covering cupboards, baths, bathroom vanities, etc. You should cover benches with a heavier cloth or drop sheet. Remove / Protect fittings and fixtures. What are fittings? Fittings and fixtures include the following: •
door handles, push, kick and lock plates, slam plates on architraves
•
light shades
•
window fittings
•
wall brackets
To prevent fittings from being damaged, you should do the following: •
Remove them (usually using a screwdriver)
•
If they cannot be removed, protect them by covering them with masking tape or by placing plastic bags over them.
•
Place fittings and screws that have been removed in a safe place to prevent loose parts from being lost.
•
Mark fittings so they go back in the same place, for instance make sure each door set goes back to the relevant door even if all sets are the same.
WARNING: Do not interfere with or remove any electrical fittings. Cover electrical fittings with masking tape.
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8.2 Choosing the correct tools
What tools, materials and equipment should you use when you are planning to apply paint, decorative finishes or wallpaper? Your answer to each of the questions that follows will decide the specific tools, materials, equipment, and PPE you will need before you begin and while you are working. Note: Remember to clean the surface you are going to work on carefully before you begin your job! What building surfaces (substrates) are you preparing?
How large are the surfaces that you are going to be working on?
bricks
narrow architraves
plaster
whole uninterrupted wall
wood
narrow spaces between windows
metal concrete
wide skirting boards
What condition is the surface in? new or old paintwork dirty greasy dusty
8.3 Choosing the correct materials
Paint, sealers, primers, fillers and other materials will generally be ordered from suppliers according to the job requirements. The site supervisor will determine what types and quantities of materials will be needed to complete the job. They will get this information from the site plans, building plans, specifications and site meetings and consultation. This information will then be given to you and your team so you have all the information you need to plan and prepare for painting and decorating.
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Materials may include the following:
•
preparatory products
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solvent borne paints such as alkyd, urethane, urethane/alkyd, urethane oil or modified alkyd resins
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latex paints such as PVA/acrylic, acrylic and styrene acrylic
•
fillers
•
sandpaper
•
When selecting plant and equipment you should check for Suitability
Chemicals You’ll be using a number of different chemicals in the trade, and some are quite dangerous if they get on your skin, in your eyes, or aren’t used properly. There is information on each container of the chemicals you use. Material Safety Data Sheets (MSDS’s) describe what’s in the chemical, the health effects, and any precautions for safe handling. If you’re not absolutely sure of the chemical or brand you are using – read the instructions and/or talk to your supervisor.
8.4 Identifying the substrate
You will use different tools, equipment and materials depending on what types of substrates (building surfaces) you’re going to be working on. Below is a brief list and description of some common materials you may have to paint over. Of course you may not be able to identify these substrate using just pictures. It is expected that you would do some discovery and find these materials on job sites, hardware stores or ask your trainer to show you samples. This is also not an exhaustive list as it would not be possible to list every single substrate that you may encounter as a painter.
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TIMBER Timbers vary widely in colour and texture, the same type of timber can range from light to dark throughout its length. Names of the same species will vary in local meaning like Victorian Ash and Tasmanian Oak being very much the same timber. All timber is known as either: hardwood; softwood; or Man-made. Hardwoods The surface of dressed hardwood has a fine grain texture with noticeable grain patterns usually running the length of the timber. The end grain will show pores or tiny holes which vary in size and must be carefully coated to be sure that they are sealed and filled with the coating. Dressed timber means that the surface is smooth after being machine planed or sanded to remove marks left by the saw. Softwoods The surface of most dressed softwoods have an open grained texture with patterns that stand out when coated which may swirl or form irregular shapes. The end grain is smooth and does not have noticeable pores. These timbers are from fast growing trees which are mostly evergreen. Man Made Timbers Today’s technology has allowed manufacturers to produce a variety of different types of timber products.
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Natural Timber:
Soft Wood timber Hard wood timber Man Made Timber:
Masonite
Ply wood
MDF (sometimes known as mush board or lake pine) Chipboard
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Masonry and Plaster Substrates: The following is a very broad description that could loosely fall into the category of masonry and plaster finishes.
Brick
Concrete Block
Cement Render Concrete
Asbestos
Fibre cement sheeting
Plasterboard
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Plastic: The Construction sector is the second highest user of plastics after packaging. Plastics are used in a growing range of applications in the construction industry. They have great versatility and combine excellent strength to weight ratio, durability, cost effectiveness, llow ow maintenance and corrosion resistance which make plastics an economically attractive choice throughout the construction sector. Plastics in construction are mainly used for seals, profiles (windows and doors), pipes, cables, floor coverings, and insulati insulation. on. Potentially, plastics have further uses as they do not rot, rust nor need regular re-painting, painting, they have strength with lack of weight, they are easily formable, and their light weight enables them to be easily transported and moved on site.
Styrofoam – sometimes used as mouldings
Poly Vinyl Chloride - PVC
Vinyl – used here as a wall siding.
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METALS Metals can be divided into three main groups: Ferrous Metals Non--Ferrous Metals Galvanized Metals Galvanised Metals These groups of metals are ferrous metals that are coated with a non non-ferrous metal. Galvanised metals are commonly used for roofing, guttering and downpipes. Common examples of these metals are: Galvanized Iron - This is iron that is coated with zinc. Zincalum - This is iron and steel that is coated with a mixture of zinc and aluminium. It is possible for these metals to rust if the protective coating of non non-ferrous ferrous metal is damaged or weathered away leaving the iron exposed.
1. Ferrous Metals All metals whic which contain iron. E.g.. cast iron, wrought iron, mild steel, high tensile steel. The primary difference between ferrous metals is the amount of iron in the metal.
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When iron and steel are exposed to oxygen and water they quickly corrode and rust forms on the surface. It is the iron content which causes the metal to rust. Metals which have a large iron content rust more readily than those with a small iron content. 2. Non-Ferrous Metals All metals which contain no iron in their composition e.g. aluminium, zinc, copper, brass, bronze, lead, chromium, tin, zincalume. Non-ferrous metals, like ferrous metals corrode when they are exposed to oxygen and water that contains impurities. The main difference is that, fine, firmly adhering corrosion deposits are formed which slow down that corrosion process. Corrosion can be accelerated by contact with a different metal. These metals are generally painted only for decoration; to avoid the need for regular polishing and for identification purposes. 3. Galvanised Metals These groups of metals are ferrous metals that are coated with a non-ferrous metal. Galvanised metals are commonly used for roofing, guttering and downpipes. Common examples of these metals are: Galvanized Iron - This is iron that is coated with zinc. Zincalum - This is iron and steel that is coated with a mixture of zinc and aluminium. It is possible for these metals to rust if the protective coating of non-ferrous metal is damaged or weathered away leaving the iron exposed. The purpose of the zinc is to protect the steel from elements that normally would lead to oxidation, corrosion and the eventual weakening of the steel. In this sense, the zinc coating acts as what is called a sacrificial anode. In other words, the zinc will protect the steel from corrosion by acting as a barrier between the steel and the corrosive agents. At least until the zinc coating has been completely oxidized.
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9
Coating Technologies
9.0 Introduction
It is important for a tradesperson to be familiar not only with the types of paints and products that they will be using in the industry but also with the ingredients of the products. This is important not only for the application but also the storing and handling of materials The choice of paint and appropriate painting system that meet the requirements of the job depends on a number of factors, including the following: Type and complexity of surface to be painted. Area of use, e.g. interior or exterior. Cost requirements. Required durability and protection of asset. Decorative effect required. Any special requirements, e.g. resistance to salt spray, resistance to industrial pollutants, low odour demands, high abrasion resistance and similar. Your reference material for this section will be the AS/NZS standards 2311 section 4
9.1 Paint Ingredients
There are four main components in any paint formula: 1) Powders or Pigments 2) Resin or Binder 3) Solvent or Carrier 4) Additives 1) PIGMENTS Prime Pigments The prime pigments contribute colour / opacity (hiding powder) to the paint. The major prime pigment used in building paints is titanium dioxide or “Titan�.
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Titanium dioxide is a white pigment and its importance is due to the fact that 85% of building paints are manufactured in white. Titanium dioxide has a high refractive index which means it bends light and hence, adds to hiding power. Titanium dioxide pigments used in paints are inorganically coated to enhance its durability and other properties for use in the paint industry. Other prime pigments are mainly used to add colour. These fall into two main groups: Earth pigments Earth pigments which are manufactured naturally or synthetically and tend to be relatively inexpensive. Organic Pigments These are manufactured by chemical processes and are bright reds and yellows. However they can be extremely expensive. They normally provide poor hiding power. Extender Pigments Extenders are mainly used to modify the gloss level of paints as the more pigment in a paint film, the flatter the sheen will be. Due to the high cost of Titanium Dioxide and its fine particle size, extenders are used to lower the sheen or gloss. Extenders can also be used to add body to paint and to increase its filling properties. The main extenders used are: Calcium Carbonate Barytes Talc Diatomaceous earth. 2) RESIN OR BINDER The binder can be thought of as glue which holds the pigments together and sticks them to the surface. Its other major function is to provide many of the physical film characteristics such as durability and flexibility. Two distinct groups of binders exist, those that are found in oil based paints and those used in water based paints.
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Oil Based The major group of binders used in oil based paints are Alkyds. These are modified vegetable oils. The major vegetable oils used to produce alkyd resins are: Drying oils: • Wood/Tung oil • Linseed oil Semi-drying oils: • Sunflower oil • Safflower oil • Soya oil Non-drying oil: • Castor oil Many different types of Alkyds can be manufactured. However, they have certain common advantages and disadvantages. Advantages: •
Forms a tough durable film coat,
•
High gloss levels are achievable,
•
Resistant to moisture, grease and oil,
•
Penetrate well; can be used on chalky surfaces.
Disadvantages: •
Dry film becomes harder and less flexible with age and this can lead to cracking and peeling,
•
Oil provides a food source for mildew,
•
Solvent thinned - more odour, harder to clean up, less environmentally friendly.
•
Subject to chalking when exposed to U.V. light.
Water based Unlike oil based paint resins, water based resins are not solutions but are dispersions or emulsions of resin in water. This accounts for their white appearance. These resins are synthetic and there are a number of resin types which are used in the formulation of water based paints. The major types are: Poly Vinyl Acetate (PVA)/Acrylics & 100% Acrylics. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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These resins exist as polymers and dry by coalescence rather than oxidisation. When the paint is applied, the water carrier evaporates, forcing the polymer particles together, which fuse to form a film. Water based resins are thermoplastic, which means they harden as the temperature falls below 10C. Water based resins have the following advantages and disadvantages: Advantages: •
Easy clean up with water,
•
Flexible film moves with the substrate,
•
Normally dries faster than an oil based paint,
•
Good colour retention.
•
Film breathes, allowing moisture in or on the substrate to pass through.
•
Longer exterior life than oil based paint.
Disadvantages: •
Not as tough as Alkyds,
•
Cannot get a high gloss,
Does not penetrate the surface as well as oil - should not be applied directly over chalky or crumbly surfaces. Application environments: •
PVA/Acrylic resins are used as interior wall paints.
•
100% Acrylic resins are used in exterior gloss or timber finishes.
3) SOLVENT, VEHICLE OR CARRIER The solvent or carrier in paint serves to allow the resin and pigments to be applied to a surface. It evaporates after application and does not form part of the applied film. In water based paints, the carrier is water. In oil based paints, the carrier is usually a solvent like mineral turpentine or other hydrocarbons.
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Even though the carrier in water based paints is water, these paints resist water once the fil film m has cured. However, they should not be applied in situations where they will be exposed to moisture immediately after application, e.g. When rain or condensation are imminent. Pigments + Binders = Solids Solids + Carrier = Paint The more solid content pa paint int has the thicker a coating is when dry. Usually coatings that are thicker are more durable, in certain situations such as industrial coating then it is critical to have a specific dry film thickness then solids will be an important consideration.
4) A ADDITIVES There are many different additives used in the manufacture of paint in order to determine its final performance, characteristics. For example, Zinc Oxide is used to resist mildew, to provide UV protection, to inhibit tannin staining and to add str strength to the final film. Some of the more common types of additives are: •
Fungistats - prevent the growth of mildew,
•
Coalescents - help produce a uniform film (water based paints)
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9.2 Gloss levels of Paint Finishes
•
Dryers Anti skin - assist in oxidation for oil based paints
•
In-can preservatives - prevent bacterial attack,
•
Thickeners - modify viscosity, enhance application properties of water based paints,
•
Wet edge additives - prevent paint from drying too quickly - water based paints,
•
Surfactants - unused to maintain dispersion of powders and resins in water based paints.
Paints are manufactured to meet different gloss specifications so that those diverse requirements relating to the area of application may be accommodated. Gloss levels range from flat through to full gloss in five stages as follows: •
Flat (matt) Up to 5 gloss units.
•
Low gloss (low sheen) Over 5 and up to 20 gloss units.
•
Semi-gloss (satin) Over 20 and up to 50 gloss units.
•
Gloss Over 50 and up to 85 gloss units.
•
Full gloss Over 85 gloss units.
Different manufacturers use terms such as ‘eggshell’ and ‘satin’ to describe different levels of gloss. Before choosing an appropriate gloss level finish, a number of factors should be considered, as follows: •
Flat or low gloss finishes tend to mask imperfections such as joints or patching. Semi-gloss, gloss and full gloss finishes highlight such defects, with the higher gloss level leading to the higher degree of highlighting.
•
Flat and low gloss finishes diffuse light and minimizes the glare, which may occur when higher gloss finishes are used.
•
Relative to flat finishes, low gloss, semi-gloss, gloss and full gloss finishes of the same generic type have an increasingly higher resistance to abrasion, staining and moisture.
•
Flat finishes are more difficult to clean and more likely to be affected by mould growth because of their rough surface texture.
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•
Full gloss and gloss finishes tend to be more durable than lower gloss finishes in exterior applications. FLAT
GLOSS
Pigment protruding through resin diffuses light.
Layer of resin on top of pigment resin reflects light back. No extenders present.
Flat or Matt
High Gloss
Semi Gloss
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9.3 How Paint Dries
All paint coatings dry by one of four (4) processes. They are: Evaporation Oxidation Coalescence Polymerisation It is important that we understand how paints dry and harden. Understanding these processes will help you perform your role as a professional painter and decorator and be confident about what you say and do on the job. Other benefits from understanding the drying processes are: Identifying different types of dried paint films Why a paint system may fail and the resulting defects that occur either naturally or by lack of knowledge of surface surf preparation and paint systems, or both. Evaporation Just about all paint coatings dry initially by evaporation. Once the thinner has evaporated into the atmosphere one of the above drying processes begins. Only a few coatings dry only by evaporation. That T means once the thinner has evaporated, the film is fully cured. Two examples are: Shellac – which is thinned with methylates spirits Lacquer – which is thinned with C3 thinner
After evaporation of the thinner, further changes to the coating take place. So when paint is referred to as being ‘touch dry’ it does not mean that it has completely hardened. For paint to completely harden it may take up to seven days or more.
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Oxidation We can describe this as simply being a coating that will powder up. We can identify an old oil based coating by wiping our hand across the surface and removing the oxidised layer sitting on top of the coating. As oil based coating ages the powdering gets worse. This is just the natural breakdown of the film over time. This m means eans that the binder is breaking down and the solid components of the paint (pigments and extenders) will come to the surface because the binder can no longer hold them together. Of course, the environment in which the coating has to survive has a bearing on how long the coating will last. Technically speaking – the drying oils in the paint chemically unite with oxygen. Oxidation occurs rapidly in the first 16 hours and then continues slowly over the life of the paint system. Coalescence The word coalescenc coalescence e means coming together. The thinner in the coating ((e.g. water) has the job of keeping the solution in a liquid state and, also keeps the particles (molecules) of BINDER apart.
Once the particles of binder come into contact with each other they combine to form a solid continuous film. The paint chemist makes this happen by introducing coalescing agents.
Generally, coalescence refers to water based paints. In this stage of the drying process, the coalescing or coming together occurs as soon as the thin thinner ner has evaporated into the atmosphere.
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Polymerisation This means many parts coming together ((e.g. e.g. Two pack paints). This is a chemical reaction which follows on after coalescence. The molecules (particles of binder) continue to “squeeze” or meld together to form a continuous film.
Paints that polymerize are usually chosen for their ability to resist abrasion and chemical attack ((e.g. Concrete swimming pool).
9.4 Paint Systems
There are many different types of paint coatings available which generally fall into the following categories: categories •
Primers (first coat)
•
Sealers (as the name suggests – sealing the surface off). The following coats will only survive if the correct choice of both primer and sealer is made.
•
Undercoats (intermediate or middle coats)
•
Fini Finishing coats
PRIMERS A primer is simply the first coat applied to the substrate. It is the foundation of the paint system and must help to protect and maintain the substrate in its original condition. Function of a primer is: •
To make absorbent surfaces non-absorbent absorbent
•
To provide maximum adhesion between this coat and the following coatings
•
To form a barrier over chemically active surfaces such as new concrete, cement render or set plaster
•
To protect metals against rust and corrosion, i.e. Ferrous and nonfe nonferrous metals.
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SEALERS Sealers are special purpose coatings that can be broadly divided into three areas: •
Acrylic based sealers
•
Spirit based sealers
•
Oil based sealers
Acrylic sealers These sealers are designed to: •
enable same day re-coating
•
be applied over masonry, set plaster and paper faced plasterboard
•
become the foundation of the acrylic paint system because they are compatible.
Spirit based sealers Are designed for use over surfaces which have a tendency to soften or stain through following coats e.g. shellac and act as a barrier to a range of stains, inks, dyes etc. from staining through to the top coats •
Oil based sealers
•
Are designed to penetrate and bind loose powdery surfaces
•
To seal highly porous surfaces e.g. Hardwood –flush panel door
•
To seal cement type surfaces
After the sealer or primer is applied be careful when abrading (sanding) that you do not sand through the coat or you will need to then spot prime the bare areas again. UNDERCOATS Undercoats or intermediate coats are applied between the primer or sealer and the finish coats. They are also applied over previously painted surfaces (after correct surface prep) before the top coat. The undercoat must be compatible with the rest of the system. The functions of an undercoat are: •
to provide opacity (coverage or hiding power)
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•
to provide good sanding properties (oil based)
•
to provide a bond between the top coat and the primer/sealer (pigment and extenders provide this)
Finish Coats These are the final coats that supply colour, gloss level and quality of appearance. The level of skill of the operator and the correct surface preparation will be reflected here. The functions of a finish coat are to:
9.5 Selecting Paint Systems
•
protect the surface from the effects of the weather, chemical attack and abrasion
•
decorate the surface (colour)
•
provide colour to identify and label surfaces for example, red or green for safety signs, pipeline colours, blue for site safety signs etc.
•
enable surfaces to be cleaned.
A paint system is simply a number of coats of paint applied to a substrate. Each coating has a specific purpose. This system could consist of: •
A primer and/or sealer
•
An undercoat
•
A finishing coat
The chosen system could be either water based or solvent based. As a painter and decorator it is expected that you can select and recommend the correct paint system for each job that you encounter. Through practical experience and the use of resources available to you your confidence will increase in this important area. An understanding of substrates, surface preparation and the correct coating system required will increase your reputation in a competitive environment. It will also lessen the chances of embarrassment when clients ask questions or when problems arise on the job.
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Points to consider when selecting a paint coat system are: •
Is it interior or exterior?
•
What are the substrates to be coated?
•
Is it new work or previously painted?
•
The type of environment this system has to survive in, e.g. high humidity areas such as bathrooms, laundries. Industrial areas such as factories. Marine environments etc.
These days with the use of the internet or simply talking to shop staff in a paint shop one can gain advice on a paint system. However understanding the makeup of the range of substrates and the makeup of each coating (primers, sealers, undercoats and finish coats) and why that particular coating is the correct choice is what separates the professional painters and decorators from someone who may be guessing. The more confidence you have in this area the easier you will find it to talk to clients and to put together your quotes. This confidence will also show through to people or clients you will encounter throughout your working life. For paint systems as detailed in the AS/NZ2311 standards please refer to Appendix II Paint systems – AS/NZ2311 :
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10 Coating Defects
10.0 Introduction
Identifying wet and dry film defects and their cure is another difficult area to become confident in. Generally speaking, if we know what makes a correct system from new (and of course surface preparation) then something(s) from this system is missing. If you diagnosed this incorrectly it could reflect on you or the business you work for.
10.1 Types of Paint Coat Defects
We can divide these defects into five (5) broad areas •
Poor surface preparation
•
Poor application techniques
•
Incorrect use of materials
•
Environmental causes (rain, frost etc.)
•
or ALL of the above
Some defects are noticeable soon after application; others may take time before they appear. There are many paint and or surface defects. You will need to be able to recognize these and identify the causes and ways to cure them. Bleeding This is when discolouration “bleeds” through a paint system because something on the surface has been dissolved by the paint. Possible causes are: Surfaces which have been coated with bitumen, or contaminated with felt pen or nicotine. Knotty or resinous woods which have not been correctly prepared or sealed.
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Solution: Remove the stain by sanding or washing. Use a manufacturer’s stain sealer. Oil based undercoat or polyurethane may work as well. Blistering Possible causes are: Moisture is trapped in timber (maybe from new or entering from exterior) and is brought to the surface by heat (the sun). High temperatures and dark colours may also cause this. Resins or sap comes to the surface from knots due to heat or sunlight Moisture is trapped in plaster or render. In some faster drying paints (e.g. Lacquers) thinners can be trapped below a quick setting paint film. Solution: Use a moisture meter to make sure the timber is at an acceptable moisture level e.g. 18% to 20%. Use light colours (if possible) as they are more resistant to blistering than dark colours (especially external). Coat resinous knots with shellac or knotting material. Use permeable coatings (which allows the substance to breathe) or wait until the surface is dry. Use heat-resistant paints. Chalking (oxidation) Chalking is the formation of a powdery deposit on the surface of a dry paint film. This is the result of the binder breaking down over time and the now under bound pigment is left on the surface. Possible causes are: Not enough binder because of over thinning. The thinner dissolves some of the binder. This can happen even to new paint Using interior paints on exposed or exterior surfaces. Ultra-Violet light. The sun also causes the binder to break down over a period of time and cause chalking. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Solution: Only thin paint according to manufacturer’s instructions, or according to the conditions at that time, for example, as paint is sitting in a paint pot throughout the day the thinner in that paint will slowly evaporate. Seal any absorbent surfaces. This applies to new work and also to repaints where you may have sanded (abraded) back to bare in some places. Cissing This is the failure of the paint film to join or form a continuous coating. The paint film shrinks back in globules (like putting water on a freshly polished car bonnet) leaving small round bare patches. Possible causes are: Painting over greasy surfaces e.g. silicon, Vaseline etc. Painting over very smooth glossy surfaces. Finishing over an oily undercoat with acrylics. Solution: Thorough washing and rinsing of the surface with a suitable degreaser e.g. Sugar soap. Sand thoroughly to remove all traces of gloss or by chemical means such as strong alkaline. Cracking or Crazing This is the splitting of a paint film due to the final coat being unable to expand the same as the previous coat. Possible causes are: Applying hard coatings (gloss enamel) over soft, elastic coatings. Recoating before the undercoat has dried. Adding excessive driers e.g. Terebine. Solution: Make sure you choose the correct paint system. Allow specified time (or even longer sometimes) for drying before recoating. Add only the minimum amount of driers.
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Efflorescence This is where the moisture and the salts that are that are in the substrate (lime and water) come to the surface of the substrate. This results in a white powder deposit on the surface. This powder must be removed before painting by either brushing off with a stiff bristle brush/broom or by chemical means. Possible causes are: A lack of correct surface preparation. If using a chemical wash to neutralize the surface then care must be taken as moisture and some salts may be put back into the substrate again. Allow ample time for the moisture content to dry out as it is the moisture that carries the salts to the surface. Solution: Again, follow manufacturer’s recommendations for surface preparation. Allow ample time for the substrate to dry out. Remove the white salt deposit by dry brushing before applying a paint system. Flaking The splitting of a dry paint film through at least one coat as a result of aging, which ultimately will lead to complete failure of the paint. In its early stages, the problem appears as hairline cracks; in its later stages, flaking occurs. Possible causes are: Use of lower quality paint that has inadequate adhesion and flexibility. Over thinning or overspreading the paint. Inadequate surface preparation or applying the paint to bare wood without first applying a primer. Excessive hardening and embrittlement of alkyd paint as the paint job ages. Solution: Remove loose and flaking paint with a scraper or wire brush, sanding the surface and feathering the edges.
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If the flaking occurs in multiple layers of paint, use of a filler may be necessary. Prime bare wood areas before repainting. Use of a top quality primer and top coat should prevent a recurrence of the problem. Poor opacity This is the failure of the paint to obscure (cover, hide) the surface. Possible causes are: Uneven paint application causing a patchy appearance. Spreading the paint out to thinly. Over thinning the paint Applying light colours over dark. Solution: Take care to spread and “lay off” the paint film evenly. Make sure you put enough paint on the surface by using a good brush, roller or spray technique. Only thin paint to manufacturer’s instructions. The pigments in some paints have better opacity than others and may need a second coat. Retarded drying This is when the paint film remains sticky after a prolonged period. Possible causes are when: Grease or wax is not removed from the surface There is not enough air or light e.g. Inside cupboards, basements There is an excess of universal tinters used to produce a dark colour from a light or white base. Frost or fog may cause slow drying and loss of gloss. Similar to the above cause is an excess of moisture / humidity which would also slow drying.
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Solution: Remove all traces of grease and wax Allow adequate ventilation while the coating is drying. Always avoid using too much universal tinters. It is better to start from a closer base colour. Do not paint in foggy or humid weather. Ropiness An effect that is characterized by pronounced brush marks that have not flowed out because of the poor levelling properties of the coating material. Possible causes are: Paint applied too thick. Incorrect use of brush technique. Poor quality brush. Application of latex in direct heat such as sunlight. Solution: Thin paint. Learn correct techniques for laying out with a brush. Ensure you use good quality tools. Avoid applying latex paint in hot conditions. Sheariness This is when the coating dries with an uneven gloss or sheen level. Patches of uneven gloss seen in a side light. Possible causes are: Paint edges have dried before overlapping (laying off) is done. Rapid drying or setting of paint due to high temperature or air movement. Applying paint to a porous surface. Mixing a gloss and flat or semi gloss together. Solution: Do not allow edges of paint to set. Work faster and plan your work in sections at a time. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Do not paint in direct sunlight. Only put finish coats over correctly prepared, sealed and or undercoated surfaces. Do not mix different paints together. Saponification This is when an oil based paint has been applied over cement or lime plaster that contains lime. The lime which is high in alkalinity creates a chemical reaction with the wet paint resulting in a discoloured soap like substance appearing on the surface. Possible causes are: Make sure that the surface (masonry type substrates) has had adequate time to dry or cure. Applying an oil-based paint to the substrates to early. Inadequate surface preparation. Solution: Use an alkali resistant paint. It will depend on the specification whether you use a water-based or solvent based system. Make sure alkalinity has been rendered neutral (this is where we see the use of the PH scale) by allowing the correct curing time or by using an acid wash. Water stains A stain caused by water leaving a yellow/brown stain where the water was penetrating. Treat the same as bleeding Wrinkling This is when a clear or gloss film becomes like a walnut shell. Possible causes are: Paint applied too thickly. The top part of the final coat sets but the bottom part is still soft. This prevents the film from drying out evenly because of the roughness of the film. Paint is subject to rapid drying conditions.
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Solution: Apply paint evenly (according to the wet or dry film thickness shown in the manufacturer’s specification sheets) to the substrate. Avoid painting in hot, sunny conditions. Vanadium stains Unsightly staining, usually red-brown in appearance that develops staining on light coloured bricks containing traces of vanadium compounds that bleed through any applied paint film. Hydrochloric acid, which is often applied to brickwork to remove mortar stains and residues, should be avoided where vanadium stains are present as the vanadium darkens in the presence of this chemical and becomes more difficult to remove. Possible causes are: Vanadium mineral leaching out of the substrate due to moisture. Insufficient film thickness allowing moisture to reach substrate Incorrect paint system Solution: They may be chemically treated with— Caustic soda or caustic potash applied as a 10% by weight aqueous solution; or sodium hypochlorite applied as a 10% solution. Both treatments should be rinsed thoroughly with copious amounts of clean water after the stain has disappeared. Coat solvent-borne sealer, thinning may be appropriate to allow the sealer to penetrate the substrate. Followed by two coats 100% acrylic paint. Mould & mildew Black, gray or brown areas of fungus growth on the surface of paint or caulk. Possible causes are: Forms most often on areas that tend to be damp, and receive little or no direct sunlight (walls with a northerly exposure and the underside of eaves are particularly vulnerable). Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Use of a lower quality paint, which may have an insufficient amount of biocide. Failure to prime bare wood before painting. Painting over a substrate or coating on which mildew has not been removed. Solution: Test to distinguish mildew from dirt by applying a few drops of household bleach to the discoloured area; if it disappears, it is probably mildew. Treat the mildew by applying a mixture of water and bleach, 3:1, and leave on for 20 minutes, applying more as it dries. Wear goggles and rubber gloves. Then scrub and rinse the area. Make sure you regularly rinse the rag and change the solution Apply an exterior latex primer, then a top-of- the-line exterior latex paint in flat, satin, semi gloss or gloss finish, depending on the desired appearance.
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11 Paint Application Testing
11.0 Introduction
Testing paint applications A variety of recognized methods can be used to determine the thickness of coatings. The method employed in a specific situation is most often determined by the type of coating and substrate, the thickness range of the coating, the size and shape of the part, and economics. Commonly used measuring techniques are: •
non destructive dry film methods such as magnetic, eddy current, ultrasonic, or micrometer measurement;
•
destructive dry film methods such as cross-sectioning or gravimetric (mass) measurement; and
•
Wet film measurement.
The following information is from David Beamish - DeFelsko Corporation, Ogdensburg, NY
11.1 NonDestructive Dry Film Methods
MAGNETIC Nonmagnetic coatings on ferrous substrates. Most coatings on steel and iron are measured this way. Gauges use one of two principles of operation: 1. Magnetic Pull-off 2. Electromagnetic Induction. Magnetic Pull-off These gauges consist of a permanent magnet, a calibrated spring, and a graduated scale. The attractive force between the magnet and the magnetized steel pulls the two together. As the coating thickness separating the two increases, it becomes easier to pull the magnet away. Coating thickness is determined by measuring this pull-off force. The weaker the force, the thicker the coating will be. Testing is sensitive to surface roughness, curvature,
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substrate thickness, and alloy content. Magnetic pull pull-off off gauges are rugged, simple, inexpensive, portable, and usually do not require any calibration calibrat adjustment. They are the instrument of choice when a low number of readings per day are required. Pull--off off gauges are typically classified as either pencilpencil type or roll roll-back dial models.
Magnetic and Electromagnetic Induction These electronic ins instruments truments measure the change in magnetic flux density at the surface of a magnetic probe as it is brought near steel. The magnitude of the flux density at the probe surface is directly related to the distance from the steel substrate. By measuring flux dens density ity the coating thickness can be determined.
EDDY CURRENT This technique is used to non-destructively measure the thickness of nonconductive coatings on nonferrous metal substrates. Paint on aluminium and acrylic on copper are typical examples.
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Edd Eddy y current inspection is based on the principles of electromagnetic induction and therefore has many similarities to the electromagnetic induction test method.
ULTRASONIC The ultrasonic pulse pulse-echo echo technique is used to nondestructively measure the thickness ess of various coatings on non non-metal substrates. Applications include paint on plastic, lacquer on wood, and epoxy on concrete.
MICROMETER Micrometers are sometimes used to check coating thickness. They have the advantage of measuring any coating/substrate combination but the disadvantage of requiring access to the bare substrate. The requirement to touch both the surface of the coating and the underside of the substrate can be limiting and they are often not sensitive enough to measure thin coatings.
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11.2 Destructive Dry Film Methods
CROSS CROSS-SECTIONING Coating thickness can be measured by cutting the coated part and viewing the cut microscopically. It can also be determined by making a geometrically geometric designed incision through the dry dry-film film coating and viewing it cross sectionaly with a scaled microscope. A special cutting tool is used to make a small, precise VV groove through the coating and into the substrate. Gauges are available that come complete with cutting tips and illuminated scaled magnifier. ADHESION TEST Where maintenance is undertaken at regular intervals, it is seldom necessary to strip off the old paint before repainting, but thorough surface preparation is most important. The c criteria riteria for removal of the paint system are largely dictated by the soundness of the existing coating and the type of substrate. At times it may be necessary to do a series of cuts on the coating then using strong adhesive tape tear back and determine if tthe existing coating is sound.
11.3 Wet Film Methods
film thickness gauges help determine how much Wet-film material to apply wet to achieve a specified dry-film dry thickness. They measure all types of wet organic coatings, such as paint, varnish, and lacquer on flat or curved smooth surfaces. Measuring wet wet-film thickness ickness during application identifies the need for immediate correction and adjustment by the applicator.
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Correction of the film after it has dried or chemically cured requires costly extra labour time, may lead to contamination of the film, and may intr introduce oduce problems of adhesion and integrity of the coating system. Notch Wet Film Gauge The notch notch-type, wet-film film thickness gauge is a flat aluminium, plastic, or stainless steel plate with calibrated notches on the edge of each face. The gauge is placed squa squarely rely and firmly onto the surface to be measured immediately after coating application and then removed. The wet wet-film film thickness lies between the highest coated notch and the next uncoated notch. Notched gauge measurements are neither accurate nor sensitiv sensitive, e, but they are useful in determining approximate wet wet-film film thickness of coatings on articles where size and shape prohibit the use of more precise methods, such as the lens and eccentric roller gauges. To read the notch gauge take the average of the notch where paint appears and the next clean notch. Formula: lowest clean notch + highest dirty notch รท 2 = average film thickness build.
Roller gauge Grasp the gauge with the thumb and forefinger so that the gauge body is free to turn. Place the gauge on a freshly coated surface at a thickness position greater than expected and roll the gauge to a thickness less than expected.
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The gauge may then be lifted and placed on another part of the surface and rolled in the opposite direction on the unused portio portion of the gauge. Examination of the outside eccentric disk will show thickness values at which pick pick-up up of the coating has taken place and the average of these values may be taken as the true coating thickness.
11.4 Determining Existing Coatings
Various broad classes of paints may, with practice, be readily distinguished simply by gentle rubbing of a small area with a droplet of one of few common solvents.
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12 Surface Preparation
12.0 Introduction
Premature paint failure usually occurs if surfaces are not adequately prepared before painting. Surface assessment and preparation are particularly important as the painter may be held liable for any future failure because the very act of painting a surface may be interpreted as accepting that surface as being suitable for painting.
12.1 Preparation of Unpainted Timber
Most exposed timbers used in building construction are supplied in the dressed condition, e.g. cladding, panels, windows and mouldings. Some timber products are delivered pre-treated with water repellents or preservatives. Such products may present difficulties when coated with latex systems. Where such treatments are known to have been used, the paint supplier’s advice should be sought. Standard of finish All sharp corners should be rounded or eased by planing, scraping or sanding to ensure that they can be properly coated and that their covering is not rubbed through during sanding between coats of paint. For fully exposed exterior timber, a typical radius of curvature of 3 mm is recommended for best coating performance. Dressed timber should be smooth, and free from raised or woolly grain, planing burrs, or other machining defects. The standard of finish should be appropriate to the end use Where dressed timber has been weathered for some time or has suffered handling or fixing damage, paint performance may be adversely affected. If the surface has yellowed or bleached the surface should be sanded back to as new condition before painting. Rough-sawn timbers should be thoroughly brushed with the grain to remove dust and dirt before painting.
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Nail & Screw Fixings All fixings for timber that is to be painted or stained should be taken below the surface. With the exception of fixings used acidic timbers such as redwood and Western red cedar. These should be made of a durable metal such as stainless steel or silicon bronze. Such fixings should be inserted so that the head is flush with the surface rather than below the surface. Mechanical damage or natural defects Holes or any other depressions formed in the surface of the timber as a result of mechanical damage, or natural defects such as resin or gum pockets, surface splits, checks or any areas of localized decay should be scraped clean of any loose or soft material. After the primer has been applied and allowed to dry, these areas should be filled with linseed oil putty or other appropriate external wood filler. Flexible synthetic wood fillers are preferred to linseed oil putty and all fillers used externally should be suitable for this use. Linseed oil putty should never be applied to un-primed timber. Un-primed timber will absorb the oil and cause the putty to shrink and fall away. Linseed oil putty should be allowed to harden, typically for one week, before over painting otherwise drying oils may migrate into the finish coat to cause localized staining. Plastic wood or two pack filler may be used to fill holes in timber for internal use before priming. Sanding may be required on timbers with raised or uneven grain to provide a smooth substrate prior to painting. Moisture content of timber Ideally, there should be minimal moisture content of the timber at the time of priming. The priming of timber should not be carried out at a time when the moisture content of its surface has been temporarily raised. Such as during fog or mist. Knotty timbers In some cases loose knots may be cut out and replaced with another piece of timber of the same species, provided that the replacement timber is inserted with the same grain orientation. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Cleaning Timber affected by superficial grease and oil may be successfully treated by wiping down with a solvent or waterbased degreasing agent. The removal of grease and oil that has penetrated the timber is very difficult and may not be possible. In these instances you may need to advice the client that the timber needs replacing. As soon as you paint the substrate then you accept responsibility for paint failure. Resin may be removed by scraping in conjunction with a solvent or hot air gun treatment. However, heating with a blowlamp before scraping is not suitable for timber that is to be finished with a clear coating. All sanding dust should be removed before application of the first coat and between subsequent coats. NOTE: Resin exudation may be very difficult to remove and may persist or re-occur. Dark paint colours tend to increase the temperature of the timber and exacerbate this problem. Machine priming of timber Modern practice uses factory methods to machine prime timber before sale, and it particularly applies where ‘fingerjointed’ radiata pine is used for exterior applications. This primer usually is pink and is sprayed on at the factory. The disadvantage of machine primed timber is a lack of adhesion of the primer to the timber substrate, a lack of cohesion within the primer layer or a lack of adhesion between the primer and the following topcoats. These coatings are often thin, powdery, or can be easily sanded off In this case timber should be sanded back to a sound surface and reprimed with a properly developed exterior pure acrylic primer/undercoat. Where the primer is sound, a light sand followed by the application of a solvent-borne primer should be undertaken. This will also stop tannin bleed from occurring. NOTE: Where there is doubt as to the quality of the machine primer coat the timber should be sanded back to a sound surface and reprimed. Preservatives Recent advances in preservative technology have increased the range of preservative formulations that may be encountered in treated timber that is to be painted.
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This variability of preservative formulations has led to the development of painting specifications by the major timber preservation groups. It is important to determine whether the timber to be painted has been treated, and to obtain the appropriate specification prior to the design of a painting system to ensure that compatibility is maintained. Some of the dye and water repellents used in light organic solvent preservative formulations are solvent mobile and it is important, when these preservatives are being over painted, to utilize a painting system that immobilizes the dye/repellent. Effect of timber species Some timbers, present a special problem as one of their resinous constituents strongly inhibits the drying of linseed oil and alkyd resins. An appropriately formulated primer should be used when painting these timbers. Inhibition of paint drying also occurs with redwood when the timber is not properly dry. Coloured water soluble extractives can leach out of some timbers and discolour paint. Before applying a paint system, the timber should be well primed with a stain blocking coating. Tannin bleed is a function of the type of timber substrate and the moisture content related to that substrate at the time of application. It should be noted that when applying tannin blocking paints, the longer the first coat is left beyond the normal recoat time and up to seven days, the more likely that the tannin will be bonded into the film and, thus, will not transfer into the topcoat. Oil-soluble preservative and creosote Two types of oil-soluble preservatives have been used in the past, namely pentachlorophenol and creosote. Timber treated by these processes was not intended to be painted. These products have largely been superseded on Occupational, Health and Safety grounds. Recoating may be problematic with bleeding or drying inhibition. The application of selective solvent-borne wood stains may minimize recoating problems. Man made timbers These boards are made by forming masses of small pieces of organic fibrous material, in most cases derived from wood, into flat sheets under varying degrees of pressure. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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At all but the highest pressures (hardboard), adhesives are incorporated to bond the fibrous material. Wax or other additives may also be included in the mixture, for example, to assist release from the pressure mould, particularly in the case of MDF. Dirt and grease should be removed, exposed edges stopped and holes filled and sanded back. If the board is not primed or sealed, contact with water should be avoided to prevent swelling of the fibres If the board suffers some disturbance or intervention, such as absorbing water or being sanded, routed or scraped, the fibres in the affected surface may swell or debond irreversibly, changing the local surface texture and porosity and so affecting the performance of surface coatings. For example, a primer or sealer coat alone may not be sufficient to overcome the difference between the factorysupplied surface and the damaged areas, requiring at least a further coat such as a sandable undercoat for filling and levelling. Clear finishes applied to surfaces composed of natural fibres such as timber or organic building boards can darken the surface in proportion to their depth of penetration or absorption; hence, surface-damaged areas may appear darker than undamaged areas when clear-coated, particularly with solvent-borne clears due to their greater penetration or absorption. As this effect occurs within the surface of the substrate, it cannot be rectified except by removing the surface of the substrate, or by over coating with an opaque coating system. Such effects should be avoided, by applying one of the clear coats before fabrication and installation, while the surface is in factory condition. If an affected surface appears likely to show this effect when clear-coated, a waterborne clear finish should be selected to minimize penetration and consequent variation in appearance. As these boards are subject to differences in composition between manufacturers, the selection of a coating system should take account of the likely variations, particularly in relation to MDF. Waterborne coatings can cause swelling of fibres at the surface, requiring light intercoat sanding. Tannins can bleed from bits of bark or hardwood within the board, requiring a solvent-borne coat or a tannin-resistant waterborne coat to block their migration.
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Wax or other water-repellent additives can have multiple effects, i.e. (i) inhibiting the wetting or adhesion of waterborne coats, which may be overcome by sanding back the surface of the board; (ii) inhibiting the curing of solvent-borne coats, requiring a greatly extended recoating time; and (iii) Dissolving into a solvent-borne coat during its application and then depositing on its surface as it dries, causing variable gloss development or inhibiting the wetting or adhesion of waterborne coats, requiring the surface to be sanded back before recoating. These effects may apply equally to clear and pigmented coatings. Whether the coating system selected is waterborne, solvent-borne or mixed, it should be trialled on a sample area of the board, unless that manufacturer’s production is already known not to affect the selected coating system.
12.1 Preparation of Unpainted Metal
IRON AND STEEL Bright-rolled or drawn steel surfaces will quickly discolour with rust if not protected. The degree of subsequent rusting will vary with the degree of condensation of moisture and contamination from the atmosphere. Where unsightly discolouration is not acceptable for aesthetic reasons, such surfaces should be thoroughly prepared. Hot-rolled steels are covered with a tightly adherent layer of mill scale. During normal storage and handling operations, this layer of scale becomes damaged and the exposed steel starts to rust. On prolonged exposure, all of the scale eventually separates leaving a fully rusted surface. Consequently, when a steel surface is ready for painting, it may vary between an intact mill scale cover at one extreme and a mill scale-free rusty surface at the other. The usual condition is somewhere in between. Loose rust and mill scale may be removed by hand-tool or power-tool cleaning. Chemical pre-treatments may be used after wire-brushing to remove the last traces of rust and to inhibit rust formation. In most instances, pre-treatment solutions may require thorough washing with clean water to remove excess residues. In such cases, the recommendations of the manufacturer are to be followed.
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Stainless steel Stainless steel occasionally needs to be painted for aesthetic reasons, for colour identification purposes or, in rare cases, for protection from specific chemicals, notably chlorides. Because it is generally supplied in a smooth condition, roughening of the surface is usually necessary, variously with wet and dry papers or abrasive blasting, prior to painting. Chemical etching is usually impractical because of the need to use corrosive reagents. For maximized performance, an appropriate metal primer should be used (for example an epoxy primer). GALVANISED METALS Two common forms of zinc-coated steel building products are marketed— (a) as hot-dipped galvanized product, such as preformed beams, lintels and handrails, often referred to galvanised iron (b) as coil or strip for products such as roof and wall sheeting, rainwater goods and low capacity framing and lintels, often referred to as zincalum which is commonly available as zinc and zinc/aluminium alloy-coated steel. Good adhesion of paint to zinc-coated surfaces may be obtained by the correct use of phosphate or self-etching primers. Where latex primers are to be used, chemical pre-treatment may be used to enhance adhesion; however, the use of selfetching primers is not strictly necessary. Where new galvanised metal is to be painted it should be noted that the material might be coated with a light film of oil derived from the manufacturing process. The surface may be cleaned with an appropriate water-based industrial cleaning solution. ALUMINIUM Aluminium surfaces are generally smooth and do not provide a good key for the adhesion of paint.
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To improve adhesion to aluminium, surfaces should be treated with any one of the following options: (a) Lightly abrade (with fine grade abrasive) wash thoroughly, prime and paint. (b) Chemical etch, prime and paint. (c) Treat with etch-primer and paint. Surfaces should be washed, dried, etched, primed or etchprimed as appropriate and painted as soon as possible, preferably on the same day. COPPER AND BRASS Copper and brass surfaces should be wiped with an emulsified degreasing agent, to remove all dirt and grease. To improve adhesion, surfaces should be lightly abraded with a fine abrasive such as 400 – 600 wet & dry paper, using a degreasing agent as the lubricant, and wiped clean. It is important that all loose particles of copper be removed from the work or surrounding areas to prevent subsequent staining by verdigris. Where the natural metal colour is required for an indoor feature finish, the surface may be brightened by treatment with a solution of— (a) 5% acetic acid solution (commercial white vinegar may suffice) 1 L; and (b) Sodium chloride (common salt) 40 g. The solution is used at ambient temperature. After treatment with the solution, the surface is washed with water, dried, and then coated as soon as possible. Copper and brass substrates are usually coated with a single-pack urethane, or a clear acrylic lacquer containing appropriate corrosion inhibitors designed for this purpose. LEAD New lead surfaces should be thoroughly washed with water, dried and coated with a semi gloss or gloss latex paint. Lead should be formed and fixed before over coating.
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12.2 Preparation of Unpainted Masonry
Clay brick surfaces Clay brickwork generally requires little preparation for painting except for the complete removal of mould growth, accumulated brick dust, dirt, projecting mortar and other loose particles, and, finally, cleaning by hosing with clean water. PH tests should be undertaken to ensure that brickwork cleaned with acid has been neutralized and rinsed off Efflorescence should be removed by dry brushing. Where deep pointing or obvious holes and imperfections occur, these should be filled to prevent ponding and absorption of water. All holes should be filled with acrylic caulking compounds or manufactured exterior fillers. Grease and chalk may be removed by solvent or by washing down with water and household detergent, after which the brickwork should be washed down with clean water and allowed to dry. Highly glazed bricks should be mechanically or chemically roughened to increase paint adhesion. It should be noted that chemical roughening might be extremely hazardous. Chemically treated brickwork should be neutralized and rinsed clean. Mechanically roughened bricks should be swept clean prior to painting. Bricks with potential for a vanadium bleed and those that have previously been treated with a silicone water repellent may pose a problem. Such bricks should be sealed with a solvent-borne concrete and masonry sealer. General With few exceptions paint, including clear film forming coatings, will serve best if the concrete is cured, and is dry when painted. When new, concrete is damp in the interior even though the surface is dry, and this moisture may later cause blistering and peeling of the paint film. New concrete also has a high alkalinity, which is particularly harmful to paints containing drying oils because of their susceptibility to saponification. Although lacquers and many latex paints are generally resistant to alkalis (some PVA paints have poor alkali resistance), the presence of dampness may cause blistering.
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Surface treatments with acids to reduce the alkalinity of new concrete have been used with varied results. Such treatments at best provide only temporary neutrality of the surface; they do not affect the reserve of alkalinity within the concrete nor prevent corrosion of steel reinforcing. Any later seepage of moisture will bring the alkalis into contact with the paint film. Ageing of the concrete is considered to be more reliable than surface treatment as a means of conditioning concrete for painting, since surface alkalinity is reduced with age. Also, the free moisture content is decreased except, of course, where concrete is exposed to a permanent source of water. Table 3.1 shows recommended drying times before painting.
Loose surface material or surface projections may be removed by blocking down with a flat carborundum stone or similar and dusted off The final pre-treatment procedure is as follows: (a) Fill unwanted holes and allow curing and drying before painting. Use only water-resistant fillers such as Portland cement-based types or those comprising water-insoluble organic binders for exterior service or wet areas. (b) Remove dust and dirt by brushing, hosing, air or water blasting or scrubbing, depending upon the character and amount of contamination. (c) Remove grease and oil by the use of solvent or by washing down with water and household detergent, then wash down with clean water and dry.
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In situ precast, off-form or tilt slab concrete Dense or glazed surfaces should be roughened slightly by abrasive blasting, abrasive grinding, by rubbing with coarse abrasive stones, or by etching with 10% sulphuric acid or 5% phosphoric acid by volume. After acid treatment, the treated surface should be thoroughly washed with clean water and allowed to dry. Excess treatment with acid may result in a loose friable surface, which should be removed with a stiff brush prior to coating. The use of hydrochloric acid is not encouraged because of the risk of chloride residues and acid gases attacking surrounding metallic materials and the possible chloride ingress into concrete, which could cause corrosion of steel reinforcing. Release agents, bond breakers, curing agents, formwork oil and the like may be removed by water blasting, treatment with an alkaline degreaser, or a formulated industrial cleanser, or by a combination of these methods. The absence of these chemicals may be determined by the rapid darkening of the concrete after wetting with water. Following treatment, the surface should be thoroughly washed with water and allowed to dry. The application of a solvent-borne concrete primer is recommended if these chemicals are present or are suspected to be present. The potential for pinholes to occur in tilt slab construction may cause difficulties in the application of a paint coating and these holes should be flush-filled prior to priming and coating. Cement render Cement surfaces should be adequately cured, and should be dry, hard, free of cracks and firmly adherent to the substrate. A minimum drying period of six weeks is recommended prior to the application of solvent-borne alkali resistant paints and at least four weeks for latex paints. These periods may vary depending upon the climatic conditions. In all cases the surface should be thoroughly rubbed down (de-nibbed) with a carborundum rubbing stone or other material harder than the cement render in order to remove unwanted projecting render, loose sand and friable material and then swept clean to remove cement and other dust. Where there is evidence of mould, the surface should be treated with a proprietary fungicide, washed with clean water and allowed to dry. Efflorescence should be removed by brushing only. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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Bagged brickwork or blockwork The cement surface should be adequately cured and dried and adhered to the substrate. Prior to painting a bagged surface, adhesion checks and powdery surface tests should be carried out to ensure that the cement surface has adequate cohesion and adhesion to the substrate as poor cohesion/adhesion will lead to de-bonding of the entire facing. When applying these thin layers of cement materials it is essential that water is retained and drying time extended for several days to ensure adequate chemical reaction in the layer. If this is not possible, a poler-modified formulation should be used. Cement bricks and blockwork These materials are generally satisfactory for painting on delivery from the manufacturer but, once cemented in position, they require at least four weeks enabling the mortar to dry and cure before painting. Brushing the surface is desirable to remove any mortar or surface laitance.
12.3 Preparation of Unpainted Plasterboard
Methods used in preparing plaster surfaces give rise to fundamental differences between the surfaces of a joint and that of an adjacent sheet. Paper-faced gypsum plasterboard requires checking to ensure that all joints are prepared to smooth finish and are free of dust before the application of paint. Various defects including ‘popping and peaking’ are associated with painted surface finishes on plasterboard. Some of these relate to the methods of installation and condition of the supporting structure. A common problem encountered is a shadowing effect at the joints, particularly with gloss finishes and oblique lighting conditions. The stopping and finishing compounds over joints being slightly higher than the surrounding plasterboard cause this.
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12.4 Preparation of Unpainted Plastics
The nature and extent of surface preparation necessary to obtain satisfactory adhesion of paints to plastics varies according to the generic plastic type; in some instances coating may be impracticable. Apart from the need to remove all extrusion lubricants, grease, dirt and other contaminants from the surface by wiping with solvent, the impervious, smooth and often greasy surface finish on most plastics usually also necessitates roughening of the surface with fine abrasives or a chemical etch. Where the plastic is soluble in the solvent or suspending medium of the proposed coating, mechanical roughening of the surface may be unnecessary. Polyesters The surface preparation for polyesters (e.g. FRP) and phenol formaldehydes should be as follows: (a) Wipe all surfaces with acetone or other suitable solvent. (b) Lightly abrade all surfaces with sandpaper, dust off and immediately apply a two-pack epoxy primer. NOTE: Polyesters may contain waxes that can inhibit subsequent adhesion and a test area should be painted first. (c) Topcoat with paint as applicable. Unplasticized polyvinyl chloride The surface preparation for unplasticized polyvinyl chloride (uPVC) should be as follows: (a) Wipe all surfaces with mineral turpentine, methylated spirits or white spirit, lightly abrade with sandpaper and dust off (b) Immediately apply finishes for uPVC.
12.5 Preparation of Unpainted Asbestos
ASBESTOS ENCAPSULATION OR SEALING Both clear and pigmented solvent-borne and latex paints have been used to encapsulate asbestos containing surfaces; however, pigmented materials are recommended as they aid quality control of coverage and identify damage in service. Most contemporary products are high-build latex membranes.
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Application is by airless spray with operating pressures as low as is practical to avoid the generation of asbestos dust during application.
12.6 Removal of Paint
Paint that is blistering, flaking or cracking should be completely removed. This may be an indication of a wider adhesion problem, and adhesion checks of the entire paint film should be undertaken. In the case of a breakdown of a solvent-borne paint system on only part of the area, some of the paintwork may appear sound and resist removal by scraping and sanding. It is possible however that this paintwork will fail and repainting may hasten such failure. Adhesion checks to determine the integrity of the existing layers should be undertaken. In cases where poor adhesion is observed, the removal of the existing coating may be necessary to give maximum life to the new coating. Similarly, surfaces exhibiting excessive chalking should be washed to give a sound base for further painting. Paint removal may be achieved by one of the following methods: Heating Heating involves the application of heat, using a flame or air from a hot-air gun, to the painted surface, which causes the solvent-borne paint film to soften and swell. The paint is then scraped off This method is effective on substrates that are not affected by heat, and is suitable for both interior and exterior use. Although appropriate safety precautions should be taken, heating may be achieved by using a hot-air gun or flames from a kerosene or LPG torch. Heating is the most effective method of removing old solvent-borne paint. It is particularly applicable where gum exudation has been a problem. Charring of the substrate should be avoided. Heat removal may be a dangerous process and requires care. Paint scrapings may ignite and set fire to grass or articles on the ground; it is good practice to wet nearby grass and shrubs before starting work and to keep fire fighting equipment such as a hose or bucket of water handy. A complete inspection of the building should be made and any flammable materials such as leaves, birds’ nests or straw should be removed.
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If a definite fire hazard exists, an alternative paint removal method should be used. The fumes from paints may be toxic and operators should avoid inhalation. Abrasive grit or water blasting Blasting involves projecting a substance at high speed or under pressure, which will remove the paint film by grinding away, as with abrasive grit, or by lifting it with a high pressure water jet. Abrasive grit blasting may be carried out in either wet or dry conditions. In each case, environmental considerations need to be taken into account. Blasting is typically used on sound substances such as concrete, masonry, metals and paving and in areas where the residue can be contained ( Grinding and sanding Grinding and sanding involves the use of abrasive materials to wear away the paint film. This may be achieved manually using abrasive paper, such as garnet, carborundum or glass paper, or with mechanical assistance such as disc sanders, belt sanders, orbital sanders or abrasive wheels. Abrasive surfaces moving at high speeds should be treated with care as improper use may injure personnel and damage the surface being prepared. This form of stripping may be used on both interior and exterior surfaces. The use of an organic vapour/particulate respirator (Class P2) complying with AS/NZS 1716 is recommended. Rotary disc sanders may be used initially, with orbital or belt sanders being used for finishing. With fixed rotary disc sanders, only the edge of the disc should be used and care should be taken to avoid pressing the disc into soft surfaces. Small areas should be sanded by hand. Airborne dust from sanding can be a health hazard. Where appropriate, operators should wear either a respirator or face mask. Chemical stripping Chemical stripping involves the use of a chemical means of removing paint and is broken down into three general classes. Not all methods will work on all paint film types, and the effectiveness of a method should be established by trial with a test area or reference to the manufacturer’s recommendations. Chemicals may be variously applied as a thixotropic gel, a poultice or a tape to prolong the stripping action and provide greater effectiveness of removal.
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The three classes of chemical stripping are the following: (i) Fast acting solvent stripping A single solvent or mixture may be used to remove paint and these systems are particularly effective for removing thin layers. The solvent usually causes the old paint film to ‘fry’ up and is easily removed from the surface by scraping. Methylene-chloridebased strippers are commonly used on solvent-borne paints. This solvent is highly toxic and appropriate safety precautions should be taken. Special attention may need to be given to the neutralization of alkali residues due to the wax content of these systems. (ii) Slow acting solvent stripping A mixture of solvents in a paste or gel may be used to remove paint and these systems are particularly effective for thick or multi-layered films. The mixture softens and penetrates the paint film, often many layers thick, to allow easy removal by scraping after an extended contact time. Residues may be removed by water wash down or simple neutralization techniques and these systems are generally less toxic. (iii) Chemical stripping A mixture of a chemical, such as ammonia and caustic soda, in a proprietary paint stripper. This procedure is usually much slower than fast acting solvent stripping but is more environmentally sound and very suitable for moulded surfaces. Special attention may need to be given to the neutralization of alkali residues. Some chemical strippers may attack some substrates notably zinc, aluminium and some timber species. Scraping Scraping involves the removal of old paint film by scraping with a sharp edge. There are many specially designed tools for this purpose, ranging from knife edges to specially designed hook scrapers. Scraping is usually followed by sanding and may be carried out on both internal and external surfaces. Removing Paint off timber and hardboard surfaces Holes or depressions in timber due to mechanical damage or natural defects such as resin or gum pockets, knotholes and surface splits should be scraped clean of any loose or soft material and, after priming, should be filled with fillers compatible with the proposed paint system. Timber that is particularly resinous may need to be heated using a hot-air gun to allow subsurface resin to diffuse to the surface for subsequent mechanical removal prior to painting.
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Some timbers (including radiata pine) are susceptible to resin bleed. Where solvent-borne preservative treatments (e.g. light organic solvent preservative) are used, resin bleed is more common. Resin exuding on the surface of timber, or through paint, should be scraped off before painting. Where the resin is still soft, wiping with mineral turps will help remove residues. Heating with a hot-air gun will bring resin to the surface. Heavy resin bleed is likely to re-occur over summer months and the only completely successful treatment for badly affected timer is replacement. Where the appearance of timber has discoloured or otherwise deteriorated due to weathering, it should be sanded or dressed back to a firm, fresh surface. Indeed, exposure of the timber substrate for even a few weeks of weathering will have a detrimental effect on the adhesion of paint coats. Where timber has decayed, the source of the moisture causing the decay should be eliminated. Leaking spouts or pipes, poor flashing and improperly sealed butt joints are frequent causes. Areas of damaged or decayed timber should be scraped out or, where the area is extensive, cut out and neatly replaced. Corroded nails that have sprung or become loose should be withdrawn and corrosion-resistant nails placed in a new position. Provided that adequate fixing is achieved, it may be preferable in some circumstances to repunch loose or sprung nails. After punching, all nail holes should be primed and puttied. Removing paint off paper-covered plasterboard Paint flaking from loose, powdery, or otherwise unsatisfactory surfaces should be completely removed and sealed with a solvent based sealer. Paint applied to interior walls should first be scraped and then sanded. If the remaining paint is considered unsound, it should be removed with appropriate chemical or solvent strippers. Bare surfaces should then be treated as for new work. All surface cracks, pores and irregularities should be filled with an appropriate filler, trowelled smooth and allowed to dry. When dry, the treated areas should be lightly sanded to a smooth finish.
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Removing paint off masonry and concrete surfaces Because of the absorbent nature of masonry and the consequent penetration of paint into the surface, the use of abrasive grit blasting is the most efficient method of cleaning. This is only satisfactory on exterior surfaces, whereas solvent or chemical strippers are satisfactory on interior surfaces. The following faults in surfaces of concrete, cement render or brick masonry should be treated as indicated before painting: (a) Crumbling mortar Rake out crumbing mortar, make good with fresh mortar and allow to dry thoroughly before painting. (b) Dampness Locate and remove the source of moisture. Dry out dampness before painting. Where any doubt exists, the use of a moisture meter is recommended to establish that the wall is dry. Paint or ‘scalers’ applied over an area to ‘cure’ dampness will either fail after a short time or divert the damp into another position; e.g., higher if the source of water is from the ground. (c) Corroded bricks Replace isolated soft or underfired brickwork before painting. Alternatively, the consolidation of corroded bricks may be an option. (d) Filling of cracks and crevices Remove all loose matter from cracks and crevices and fill with an appropriate compound. Clean out deep holes in masonry, wet with water and fill with mortar no stronger than the existing substrate or an appropriate patching compound and allow to dry. If there is any doubt about whether a crack is continuing to widen, seek expert advice as to the cause. A check of crack movement may be made by gluing to one side of the crack a glass microscope slide positioned over the crack. The position of the other side of the crack is marked on the slide and observed for a few weeks or months, as appropriate. (e) Moss and lichen Remove all loose and powdery growth in moss-affected areas. Treat the affected surface with one of the following solutions: (i) 20 g of copper sulphate (hydrated) in 1 litre of water. (ii) Benzalkonium chloride solution.
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(iii) Other equivalent proprietary solution. 1 The solution containing copper sulphate should not be applied to zinc-coated or aluminium surfaces because of discolouration and corrosion nor should any run-off impinge on such surfaces. 2 Copper sulphate, benzalkonium chloride and some proprietary solutions are poisonous and should not be allowed into drinking water or stormwater drains. The procedure should be as follows: (a) Apply the solution to the affected area and leave until the moss and lichen turn brown and become loose. This usually occurs within three days to six days. Q,) Scrub down with a hard bristle brush, hose liberally with water and allow to dry. (c) Swab the treated areas using a solution of one volume of household bleach diluted with two volumes of water. Allow to remain for 30 mm. (d) Treat the surface with a proprietary algicide solution following the label directions. (e) Wash down with clean water and allow to dry thoroughly before painting. After treatment to remove moss and lichen, surfaces may be discoloured. Surrounding surfaces should be protected to avoid unnecessary staining. (f) Spalling concrete Usually caused by the expansion or rusting of metal reinforcement within the concrete causing surface concrete to fall off. (g) Old paint coatings Remove old coatings by the use of water/abrasive jets. Removing paint off metalwork Any of the above mentioned systems may be used for removal of paint off metalwork. However, interior and exterior limitations should be borne in mind. In severe environments, reinstatement of coatings should be in carried out immediately. In mild environments, reinstatement may be deferred to suit the maintenance program owing to significantly reduced steel corrosion rates. It will be necessary for corroded areas to be appropriately cleaned and spot-primed before application of the recommended system. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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Removing paint off plastic surfaces Plastic surfaces are not generally resistant to abrasives or solvents; however, the use of chemical strippers and mild abrasives offer the most suitable methods for stripping painted surfaces.
12.4 Removal of Wallpaper
If possible, existing wallpaper should be removed and the surface washed down to remove all traces of adhesive. If the surface has been papered with a strippable vinyl; remove the vinyl coating and check the backing paper for adhesion. If the backing paper is unsound remove it.
If it is firmly adhered to the surface, it can be used as a lining paper base for your wall covering. (Ensure that the joins do not coincide with your joins). PLASTIC COATED VINYL If the previous paper is plastic coated and cannot be removed without substantial damage to the surface occurring: •
Ensure that the surface is clean and dry.
•
Thoroughly sand down the entire surface to provide adhesion and pay particular attention to the joins to ensure that they are not loose or overlapped.
•
Apply a coat of alkyd based flat enamel to the papered surface. A water based sealer should not be used as it raises bubbles and joins in the paper.
•
Allow the coating to dry and apply a coat of size.
REGULAR OR PLASTIC COATED PAPER These papers must be removed before repapering can be attempted. •
Soak the entire wall surface, twice .
•
Allow time for the solution to soak into the paper.
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•
Scrape off the paper with a broad blade stripping knife.
If the paper is difficult to remove: •
Make a series of knife cuts across the paper to allow the solution to soak in.
•
Be very careful with knife cuts.
•
Cut the paper only as damage to the plaster wall is difficult to repair.
•
A stiff wire brush is a useful alternative to scratch the surface.
•
Resoak the surface several times. Allow time for the solution to soak into the paper.
•
Strip the paper with a broad blade stripping knife.
If this procedure is not successful, a steam stripper will have to be used. STEAM STRIPPER A steam stripper consists of a water tank that boils water to produce steam.
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The steam transfers down a hose to a steaming plate that is held against the wall covering to be removed, the steam penetrates the surface softening through to the adhesive. The covering can be easily scraped from the surface with a stripping knife. Your trainer will demonstrate how to use the wallpaper steam stripper. Safety Precautions (i) Keep power/gas connections in safe condition. (ii) Do not let the water level drop below safe operating levels. (iii) Keep the steam hose free of kinks or bends to protect blockage and safety valve blow out. (iv) Be careful when refilling, the filler cap will be very hot. Steam may escape and burn. Always reseal the filler cap properly. (v) Never leave the steam stripper unattended whilst it is operating.
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13 Substrate Repairs
13.0 Introduction
In this section we are going to illustrate some basic substrate repairs. Of course the best way to learn how to repair a substrate is through training and hands on participation. Hands on experience will be provided by your trainer and through on site experience. This section does not cover every type of substrate repairs but focuses on some of the main repairs you are likely to encounter as a painter and decorator including: Repairing discolouration of paint films Plasterboard repairs Repair of small cracks
13.1 Repairing Discolouration of Paint Films
Stained surfaces and surfaces in areas such as kitchens, bathrooms and laundries will need to be washed down prior to painting. Smoke stains, soap, grease, finger marks on doors and other woodwork must be removed prior to painting. Some stains could be mould, efflorescence, ink or many other things. If in doubt as to the nature of the stain use the following guide lines from the AS2311:2000.
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If surfaces that are to be painted are not thoroughly cleaned, the following faults may occur: •
Slowness or lack of drying of the paint film
•
Staining of the paint film, due to solvent action upon grease, smoke, oil, etc.
•
Poor adhesion of the paint film to the surface
Most stains can be removed with alkalis such as: •
Tri-sodium phosphate (sugar soap). This is the preferred chemical treatment as it is less hazardous then sodium hypochlorite. Tri-sodium causes a foaming action due to it being a surfactant so it is more effective on the substrate and tends not to evaporate and run off as fast as sodium hypochlorite. Dispersion in water should be as specified by the manufacturer.
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•
Sodium Hypochlorite (household bleach) this solution should be dispersed in water to a dilution of approximately 10 parts water to one part sodium hypochlorite. Ensure you wear suitable PPE.
Water Blasting The use of water blasting equipment to remove deteriorated coatings is an effective method, but should be restricted to masonry, brick, stucco, steel and similar surfaces. Water blasting timber is successful to a limited extent. Water blast machines use water under high pressure. Water is conveyed from the machine through a high-pressure hose to a gun, using varying shaped tip centres they create different blasting patterns. Most water blast machines have a detergent cycle and are very successfully used for washing down.
The use of a wide tip reduces the blasting capacity of the machine. To break up surface contamination or chalk, apply detergent mix to the surface and broom down. Wash off the surface using the gun to remove residue.
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13.2 Plasterboard repairs
Cracks Cracks can be repaired using a caulking gun and latex caulking compound sold in tubes. First dig out the crack a little first before filling and ensure you leave a smooth level surface wiping off excess.
Repairing small holes Most small holes can be filled with a ready mixed compound or for more strength you can use a plaster compound such as cornice cement. Do not use base coat as this is a cement based product and does not sand easily nor smoothly. There are many products available for this type of repair.
Using the butt of the filling blade handle press around the edges so that you don’t get protruding pieces of paper or plaster when doing the repair.
Some holes that are slightly larger may need a fibre tape to support the stopping compound until it dries.
Do not over fill, if the stopping compound is too thick it will have an impact on the drying. Sanding too will ill be much more difficult.
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Sand to an even smooth finish.
Repairing large holes
Larger holes may need to be repaired by replacing a small square area of the sheeting as follows.
Measure the hole that needs to be repaired. ut a piece of plasterboard Cut or fibro of the same thickness of the board but larger than the hole.
Place the cut-out piece over the hole and pencil the outline. Mark the top of the cut-out piece so that you place it in the right way around.
Using a sharp cutting knife or a hole saw carfully cut the along the pencil mark. Make four cuts from the hole outward to the corners so that you can press the plaster inward to remove. Make sure you do not damage the inside lining of the plasterboard.
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To make sure you have not damaged the inside of the plasterboard run your fingers around the inside edge and inspect the hole before proceeding. Check that the piece you cut fits into place nicely. If it is too tight trim around the outside of you cut piece. Cut another piece of board longer than the hole but shorter than the height of the hole to act as a backing strip for the repair.
Push a flat head nail or clout through this peace. Force a fast drying adhesive around the inside edge of the hole and on the edge of the backing strip. Place the backing strip through the hole, using the nail pull the board hard against the adhesive. adhesive An affective product that works surprisingly well as an adhesive and that dries dr fast is resin based filler such as body filler fil or builders bog. Clean excess of the face of the board. Allow to dry. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Alternatively you can fix timber behind as a backing strip as illustrated here. This is a much faster way to place a backing piece but it’s debatable as to if it is stronger.
Once backing piece is dry place the repair piece that you cut earlier into the square and using mesh tape and plaster compound fix the repaired piece into place.
When the first coat of plaster compound is dry then top coat the repair with a sandable filling coat to smooth out imperfections and scratches.
13.3 Concrete & Cement Render Repairs
Movement causes cracks in cement rendered surfaces. If the source of movement cannot be stabilised, cracks, which are repaired, are subject to further movement. Poor foundations, age of building, and road traffic are all contributing factors to cracking in cement render work.
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Rake out loose paint and render and undercut the crack using a stripping blade to provide a suitable surface for the filler.
Undercut the opening to prevent the repair from falling out. Dust out loose materials. in the opening with a Wet-in brush and clean water. The water will slow down the absorption rate and help prevent the stopping materials from drying too quickly and possibly shrinking and cracking.
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Fill the widened crack with a mortar of cement, sand, water and an acrylic additive to provide flexibility. A better option is to get an exterior grade acrylic render that has grit in it to provide the same texture as cement render. Or you could use an exterior dry compound that is specially formulated to give an appearance of render but is much more flexible.
What to avoid! Ensure that the profile of the repair matches the profile of the substrate. Look at these examples of how the patch stands out because the profile did not match.
Cracks considered not major in nature should be filled with an acrylic caulking compound.
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Concrete Cancer
Concrete cancer, is actually the corrosion of embedded steel within the concrete and not corrosion of the concrete itself.
This usually becomes apparent through surface spalling and de de-lamination, lamination, caused by the surface of the steel that has corroded, ex expanding panding and putting internal pressure on the concrete structure, once the expanded steel builds sufficient pressure, the concrete will crack and rupture. Once this is identified, remedial work needs carrying out to ensure the concrete structure retains its strength. As a painter you may be asked to do minor repairs of this sort of defect. Engineer specification should be sourced before the commencement of any repair on concrete cancer. It is worthwhile noting that concrete cancer should not occur in the fir first st place if a proper membrane coating was applying at the beginning.
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13.4 Metal Repairs
Metal surfaces that have been painted before require cleaning down before repainting. This can be done by an angle grinder or wire brush. For the removal of old paint, an angle grinder with a sanding disc fitted is very good. Remove any paint areas that have lifted or cracked. Any rust areas should be removed. If not removed, the rust will continue to spread and come through the new paintwork. Wire brushing will also re remove move any chalking of the old paint. All surfaces should be completely dry and free of any dust, oil and grease before painting takes place.
Where necessary you may need to cut the corrosion out and do repair on the metal using resin based filler such as auto body filler or builders bog. It is important to note that cutting out corrosion should only be done where it is absolutely certain that doing such does not affect the structural integrity too adversely.
13.5 Timber Repairs
If a timber surface has se severe vere faults, such as chipped edges, split timber, broken joins or bad stains, it should be pointed out to the client and no responsibility should be taken for their successful removal. Many severe faults will require repair by a carpenter or joiner. Any fa faults ults that are found in the surface should be repaired. There are many faults that can be found in furniture timbers. The following table lists the common faults and how to rectify them. Holes - Nails, staples, insects, screws and drills Generally holes need to be filled with a suitable stopping. Small holes can be filled with lacquer or water putty. Larger holes should be filled with epoxy filler as this is less likely to shrink.
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Bruises - Timber being knocked by tools or careless handling Bruises, if not too deep, can be steamed out. To do this wet the bruised area with a drop of water or apply a damp cloth. Then apply a hot iron. The heat from the iron will force steam into the timber fibres forcing them to swell and the bruise will have disappeared.
Veneer Dents - Veneer surface has been bruised or dented by coming into contact with a harder foreign object. The difference between a dent and a bruise is that a dent is deep enough to have broken the timber fibres. Dents may need to be treated as holes. Veneer blisters - The glue under the blisters veneer releases because of heat, moisture or insufficient glue. Blisters can be easily repaired. Split the blister with a scalpel and insert some glue under the veneer with a syringe. Apply pressure to the area to hold the veneer down. Always remember to have some paper underneath your weight to prevent it sticking to the veneer surface. Machine marks - Saw or cutter marks left in the timber from the machining process. These will need to be removed especially if you are finishing the timber in a clear finish. These need to be sanded out to produce a smooth surface for finishing. Remember to sand in the direction of the grain. Water marks - Rain drops or splashes The best way to avoid them is to wet the whole surface. This will remove any patchiness due to the stain being absorbed at a different rate. The slight grain raising effect from the water will produce a smoother finish when sanded. Scratches across sanding marks, pen / pencil marks - A foreign object or abrasive paper being dragged across the grain. Pen/pencil marks are often left by joiners/carpenters during assembly of timber fixtures/features. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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These are a concern if you intend to produce a clear finish on the surface. All of these can be treated the same. Use a suitable grade of paper to remove the scratches and then work your way up through the grades to produce a finish suitable for finishing. Knots - Can sometimes fall out or become loose (called ‘dead knots’) Loose knots can be glued into place and then when dry may need to have a stopping around the edge to fill any gap. Missing knots can be treated as a hole and filled with epoxy filler. Glue marks Occur during assembly of timber fixtures/features. Usually around joints but not restricted to that area. Glue marks can easily be sanded out using a suitable paper.
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14 Apply Texture Coatings
14.0 Introduction
What is a texture coating? Texture coatings are formulated on acrylic emulsion binders/resins together with pigments such as titanium dioxide, mineral fillers, texture building aggregates, fungicides and a number of special additives, to ensure proper curing under a variety of application and weather conditions. Supplied in a ‘ready to use’ semi liquid paste, these coatings are applied by texture roller, brush, spray or trowel. The products in their various grades produce differing decorative profiles that are selected to enhance the aesthetics of their surface. Their exceptional high build (as compared with conventional paint) provides greater covering over surface irregularities which would otherwise require time consuming patching making them quick and economical to apply. The cured films of texture coatings display excellent flexibility to cope with substrate expansion and contraction. Their high build nature also imparts greater protection against elements with only marginal ongoing maintenance. What is a membrane? Membrane coatings are very flexible non-aggregate coatings with excellent water resistance and durability for interior and exterior walls. Membranes provide the maximum durability, weatherability and resistance to a variety of chemicals (eg. carbon dioxide) as well as reducing water transmission of the coating system. Membranes are highly flexible and give greater water resistance over extensive hairline cracking of masonry structures.
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Why use texture coatings? Texture coatings are used for three prime reasons. 1. Provide a pleasing decorative textural finish. 2. Cover surface irregularities quickly without extensive surface levelling (ie. plastering). 3. Impart long term protection against the elements with minimal ongoing maintenance. Today’s buildings increasingly employ ‘fast track’ construction substrates. Off form concrete, Tilt up concrete, AAC (Autoclave Aerated Concrete) and Harditex exterior wall sheeting have all contributed to the growing use and need for these products. They impart a pleasing decorative finish without the need for major surface levelling (ie. plastering/rendering). This means that their installation is both fast and economical. These attributes are also useful for recoating of aged and weathered coatings without the need for extensive ‘making good’ of imperfections.
14.1 Planning
There are a number of considerations when planning to apply texture and the most appropriate texture grade to use: •
The substrate and the surface condition (ie the type of substrate / the degree of irregularities).
•
The clients texture preference.
•
The environment and climate.
•
The cost.
•
The experience of the applicator (roller, brush or spray).
•
Safety Hazards
Usually one or two of these will become the most important aspects of the decision process. For example, if the client’s preference is for a high profile spray on finish, then the ability of the applicator to be proficient with applying a high build coat using a texture spray unit is vital. If on the other hand, it is a low profile Roll-on finish and the substrate is of poor quality, a good deal of cost will be associated with surface levelling. If the project is tightly budgeted it would be advisable to choose a coarse grade of texture eg Roll On 9mm high profile as the greater covering ability will reduce the overall system cost.
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Substrate condition The diversity of texture enables the applicator to produce a variety of exciting and pleasing designs to various substrates that are new or previously painted. General surface preparation As with any painting/coating project, professional results only come from careful surface preparation, therefore the care taken in preparing the surface ultimately determines the overall success of the application. The various considerations are: •
Is the surface clean, free of all dirt, efflorescence, dust, grease and loose or flaky parts?
•
If the surface appears powdery, wash down and apply a surface sealer.
•
Finer textures will require greater care in patching of surface imperfections or irregularities. In some cases, a full skim coat may be required.
•
Appropriate primer before texture application.
•
Listed below are some typical surface preparation/s for various commonly used substrates.
Off-Form Concrete Flushing form or shutter marks – patch level with suitable compound (Acra Patch Fine or Coarse) relative to texture finish to be used and its covering ability. As an example fine textures require feather edging. Tilt-Up Need to ensure surface is free of release agents and bond breakers. A common method to show the presence of release agents/bond breakers is to splash the surface of the concrete with water. The water must not bead on surface. Paint manufactures will recommend an appropriate decreaser to remove these releasing agents. Note: if releasing agents or bond breakers are not properly removed the texture coating is highly vulnerable to failure. Cement Render Surface must not be powdery when rubbed with a finger. New Cement render should be aged for around 21 days to let fully cure. At all times, follow Manufactures Recommendations on Coating times
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Brick work and Block work Must be free of salt efflorescence, clean and sound appearance. GRC (Glass Fibre Reinforced Concrete) Surface clean and not glossy. If glossy, apply light acid etch solution. Fibre Cement Sheeting (FCS) Clean, sound and fixed in accordance with the manufacturer’s recommendation. HardiTex Cladding As in FCS, sheet surfaces along butt joint lines must be level and securely fixed. Joints are to be flushed with suitable compound and reinforcing tape. Autoclaved Aerated Concrete (AAC) Clean and sound, free of dust, surface rendering of skim coat (Acrapatch coarse) required; use higher profile textures. Previously painted surfaces Before applying texture coatings to any surface that has been previously decorated, it is essential to ensure that: •
The surface is sound and free from stains, oil, grease or dirt.
•
Old kalsomine coatings are completely removed by washing and scrubbing with water.
•
Old wall coverings and pastes have been completely removed.
•
Enamelled surfaces are firstly sanded to provide key, and then given a coat of oil base undercoat.
•
Old plaster and lining boards are firm in corners and joins.
•
Composition wall boards for interior linings such as plasterboard, asbestos cement or the new fibrous cement sheeting, masonite, hardboard etc, present differing problems.
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Texture could not be guaranteed to last over F/C sheeting or masonite due to the expansion and contraction at the joints between the sheets. If the texture coating has to be applied to these surfaces, the following procedure could be adopted: •
Seal surface to eliminate porosity
•
Make sure sheets are well nailed to minimise movement
•
Punch nail heads (counter sink)
•
Joints are to be flushed with suitable filling compound and reinforcing tape (Meeting manufactures requirements).
•
While filling compound is still wet, force reinforcement tape into it with the aid of a squeegee or large filling blade, If needed a final filler can be applied.
•
When dry abrade the surface, feathering the edges.
If these procedures are used it helps to reduce the movement at the joints due to temperature fluctuations, and minimises the risk of the texture cracking. Climate and environment This takes into account a number of different aspects that the texture coat is going to be exposed to. Environment and climate is the elements the surface is exposed to. Exterior: Sunlight; Rain; Traffic; High humidity; Frequently cleaned; Salt,etc. Interior: Wet areas (high humidity); Kitchen (frequently cleaned); Traffic The environment can also be were the substrate is situated on a building, like on the southern side, up high, tight or confined spaces. The environment could also take into account the access to the substrate, safety hazards near or around surface to be textured or within close proximity of other substrates that have to stay protected from the texture coatings etc. This could influence the application method / final pattern required or cost involved. Caution: Weather conditions have a dramatic effect on the working time of a texture coating, extremely hot and dry conditions will set off the texture very quickly. Measures may to be taken to minimise the problem by choosing another time of day, working smaller areas, wetting the substrate (masonry only).
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Note: most manufacturers recommend that texture products be coated with a membrane when exposed to the exterior elements. Experience of the Applicator Textured coatings require a high degree of applicator expertise to achieve acceptable results. Large areas are particularly challenging to the inexperienced. Roller application is amongst the easiest to master.
14.2 Application of Texture
First coat (sealer) at specified rate per m2; Manufactures will recommend appropriate sealers/primers for texture coating system being applied. This information will be found on the products technical Data sheet. Second coat by specified method (brush, roller or spray gun) Depending on the product chosen, manufactures produce powder mix or premix textures and will specify the appropriate application method. One of the following tools, brush, roller or spray gun can be used for application or a combination of two or all three. Texture coating pattern is generated straight after the application of the second coat while the product is workable. It is essential that a consistent pattern be maintained throughout the job. Consistency of pattern is best achieved by: •
Maintaining a wet edge
•
Maintaining stable environment
•
The same person keeps same task (create pattern) for duration of job.
•
Large areas may require masking into smaller more manageable areas
Third coat (for decorative finish or colour) as specified (long nap roller or airless spray gun). This coat is critical for exterior substrates as it provides protection from the elements the coating system it is exposed to. Note: For interior surfaces the texture coating can be coated with ordinary paints to provide desired colours or decorative finish. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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14.4 Trowel on Texture
The application of texture by hawk and trowel is a challenging skill. The effects that a trowel can make on texture are very impressive. Ask your trainer to show you samples of trowel on texture. The solid plasterer traditionally does most trowel on texture effects using sand and cement. In the last couple of decades the introduction of acyclic latex texture coatings has brought the trades of solid plastering and painting & decorating to merge across skills. The solid plaster has had to come to know a little bit about coating membrane technology and the painter has to understand a little bit about solid plastering. Solid Plastering Terminology AGGREGATE: Particles of rock or mineral fragment used with various cementing materials. The term used in conjunction with plaster usually implies sand, vermiculite or perlite. BASE COAT: The first layer or layers of plaster applied over a solid background. The first application is often referred to as the SCRATCH COAT, and the succeeding layer as LEVELLING COAT or FLOATING COAT. STUCCO: A general term for plastered surfaces, but especially applied to cement surfaces that imitate stone. SOLID PLASTER: The term ‘solid plaster’ relates to plaster that is made up of a mixture of Cement, Water & Sand. It is also referred to as render.
14.5 Information on Texture Coatings
The range of Acrylic Texture Coatings have been developed over a number of years to provide durable, fast applicating surface coatings and finishing systems for a variety of masonry substrates. Whilst the physical and technical properties of the products are stringently controlled during manufacture, the ultimate performance of the coating system relies heavily on correct application with due consideration to substrate condition, surface preparation, coating sequence and prevailing climatic condition. Trade Representatives from all manufacturer’s together with the broad resources of Specialty Coatings team are also available to provide additional information where required.
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Suggested sources of information on texture coatings could be: Your local paint trade outlet www.rockcote.com.au www.graco.com.au www.dulux.com.au www.wattyl.com.au www.solver.com.au www.drywallschool.com/textures.htm Please make sure your trainer demonstrates the different samples of texture and patterns that are available.
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15 Apply Paint by Spray
15.0 Introduction
As a painter you are required to apply paint by spray onto different surfaces to form a protective paint finish. To do this you will need to plan and prepare for the work, prepare materials and application area, the set up and test of the spray equipment, apply the paint by spray and clean up the application of paint then cleanup work area, clean up equipment and store equipment and tools.
15.1 General Preparation for Spraying
Spray Area All spraying should be undertaken in a spray booth or separate spray area that is: •
clean, free from dust and dirt;
•
free of contamination from workers;
•
equipped for spray operations to be carried out safely;
•
free of naked flame, welding or persons smoking.
Safety Before spraying you should be aware of the OH&S requirements for you job site. These include relevant legislation that applies to spraying in our country or region. These may include: •
Protective clothing and equipment
•
Use of tools and equipment
•
Workplace environment and safety,
•
Handling of materials,
•
Use of fire fighting equipment,
•
First aid,
•
Hazard control
•
Hazardous materials and substances
Personal Protective Equipment (PPE) for spraying would primarily be a respirator. However other PPE should be considered as well such as overalls, hearing protection (required in some spray booths), closed shoes and eye protection. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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Respirators should be selected in accord with the recommendations of the Material Safety Data Sheets (MSDS) of the material being sprayed. Before operating any spray equipment do a risk assessment of: •
Safe operating procedures of the spray equipment. Do you know how to use the equipment safely?
•
Solvents
•
Lead
•
Chemicals
•
Fumes/gases
•
Confined work areas
•
Manual handling
•
Falling objects
•
Electrical and fire
•
Explosion from combustible materials
•
Traffic control
•
Working at heights
•
Working in proximity to others
•
Worksite visitors and the public
Emergency procedures related to operation are to include:
15.2 Conventional Spraying
•
Equipment emergency shutdown and stopping
•
Extinguishing fires
•
Organisational first aid requirements and evacuation
A conventional spray system consist of: •
Conventional Spray gun (various types)
•
Compressed Air Supply
•
Connecting Hoses for paint and air
•
Transformer/Regulator (for high pressure spray)
Types of Guns required Before attempting a spraying operation or purchasing a spray gun, give considerable thought to the type and size of spray gun required.
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Similar consideration should be given to the specifications of the gun set set-up up such as the dimensions of air holes in the air cap and paint orifice in the fluid tip as these can be tailor ma made de to suit various paints and applications. Factors to be considered are: •
Size of compressor and available air supply;
•
Number of air driven appliances or other guns utilising the supply;
•
Size of work to be undertaken;
•
•
o
small touch up work; and
o
display work etc.
Quality of finish required; o
prestige quality lacquer,
o
commercial enamel work; and
o
texture of industrial finishes
Amount of work to be undertaken; o
small intermittent spray jobs;
o
continuous production spraying; and
o
constant colour changing.
Types of conventional guns: •
Gravity Fed – this type of gun has a pot at the top. The paint drops down onto the airflow. The gravity fed guns is very good for viscous paint as it does not depend on pulling the material up to spray.
•
Suction Fed – this gun has the pot under the gun. The paint moves up to spray through a venturic action. Suction feed guns atomise the paint to a fine mist.
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This will give a better finish to fast drying thin coatings such as automotive paints.
•
Pressure Fed – This type of gun uses a suction feed gun with out a pot. Where the pot is normally connected a hose is connected that feeds from a large pot. The air is fed into the pot and the paint is forced out of the pot through pressure into the line and then out the gun. A air hose is also connected to the gun to atomise the paint. The main advantage of a pressure feed system is for applying large volumes of paint to large areas.
•
High Pressure – high pressure guns are designed for atomising thin paint for mirror finishes. You can get gravity feed and suction feed high pressure spray guns.
•
Low Pressure – these guns pressurise the pot forcing the paint into the gun. This is a good gun for applying viscous paint but it does not atomise the paint as well as a high pressure gun. It is not usually used as a finishing gun unless the finish is a high build slow drying coating such as Alkyd paint.
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•
Touch up Guns – smaller guns that are used for touching up small areas.
•
Air Brushes – these spray a very precise pattern and are used for art work.
• HVLP - This stands for High Volume Low Pressure. This gun is designed to reduce over spray and improve application accuracy and decrease waste. The high volume of air controls the direction and flow of paint. At the same time the low pressure reduces the atomisation of the paint during application. This in turn reduces the over spray and bounce back.
There are two main types of categories of guns: •
Bleeders – these guns release air continually. They are usually the low pressure guns that apply paint by forcing the paint out of the pot under pressure. If the gun does not bleed air then the pot would blow off the gun. Texture guns are often bleeders as well. The needle provides a constant stream of air, when the trigger is pulled back the texture drops down in front of the air flow through the needle and is forced out of the gun through the tip.
•
Non Bleeders – the air flow stops with these guns as soon as the trigger is released.
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for, maintained and lubricated correctly it will give the operator many years of trouble-free service. You should become familiar with the parts of a conventional gun. It is important to know how to check, clean and maintain these parts in order to achieve a good spray finish each time you use it.
Air Cap The air cap is at the front of the gun. It directs compressed air into the material stream to atomise it and to form it into a spray. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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The cross section of this spray is called the spray pattern. There are various styles of caps producing different sizes and shapes of patterns for all types of applications. The air cap is designed to atomise the paint by mixing the paint with air as the paint is sprayed. The two categories of air caps are: •
Internal Feed – the tip sits behind the air cap so that the paint and air are mixed inside the cup before being sprayed out of the tip.
•
External Feed – the air is mixed with the paint outside the air cap as it comes out of the tip.
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To select the correct air cap, consider the following factors: •
Volume of air (in litres per minute) and pressure (in kilopascals) available.
•
Material feed system used pressure or suction feed.
•
Type and volume of material to be sprayed.
Type of material feed •
Fluid tip size to be used.
•
Most air caps work best with certain fluid tip sizes.
•
Size and nature of object or surface to be sprayed.
•
Larger orifices increase the ability to atomise more material for painting large objects with greater speed; and
•
Smaller orifices usually require less air, produce smaller spray patterns and deliver less material to conveniently paint smaller objects or apply coatings at slower speeds. Fluid Tip The fluid tip forms a seat for the fluid needle which shuts off the flow of material. Fluid tips are available in a variety of sizes to properly handle materials of various types and pass the required volume of material for different speeds of application.
Fluid Tip Selection To select the proper fluid tip, consider several important factors: •
Heavy, coarse or fibrous materials require large fluid tip sizes to permit passage of the material and prevent clogging.
•
Very thin materials that sag readily are applied with small fluid tip sizes which permit more effect control of fluid pressures.
•
Abrasive materials must be handled with a tungsten needle and specially hardened tip.
•
Type of material feed to be used.
To attain a given rate of fluid flow, pressure feed assemblies usually operate with smaller tips than suction feed.
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Spreader Control The spreader or fan control enables adjustment of the spray pattern width by control of air to the horn holes. A full pattern width can be controlled down to a spot pattern - turn right for spot; and turn left for fan.
Spray guns fitted with an internal mix air cap do not have a spreader adjustment valve.
Fluid Tip, Air Cap and Needle Identification Fluid tips, air caps and needles are identified with their number or dimensions stamped on them.
Refer to manufacturer's literature for detailed information. Fluid Needle Adjustment Screw The fluid needle adjustment screw controls the travel of the fluid needle. It controls the quantity of material flow through the fluid tip.
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Cleaning and maintenance Suction Feed System
Never leave any spray gun soaking in solvent overnight. This tends to swell gaskets and destroy seals and packing glands. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Do not use wire, pins, nails or any metallic article to clean passageways or ports. Permanent damage will result. Do not drop these parts as distortion of horn holes will result. Dismantle the spray gun only when necessary as excessive stripping causes excessive wear on the threads, nuts and gun seatings. All spray guns should be cleaned after use and left in good working order.
15.3 Troubleshooting conventional guns
Material Leakage From Needle Packing Gland This is caused by: •
Loose Gland Nut tighten.
•
Dried Out Packing replace.
•
Perished Packing replace.
•
Needle packing gland leakage
Fluttering Spray This is caused by: •
Obstructed fluid way – clean
•
Loose or cracked fluid feed tube in cup tighten or replace;
•
Loose material nipple tighten.
•
Damaged material nipple seat - replace nipple.
•
Material packing gland nut loose - tighten.
•
Perished or dried out packing - replace or soften with a few drops of oil.
•
Clogged air vent in cup lid - clean.
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Top or Bottom-Heavy Pattern This is caused by: •
Horn holes partially blocked.
•
Obstruction on fluid tip.
•
Dirt on the cap seat or the fluid tip seat.
To rectify Determine whether the obstruction is on the air cap or fluid tip, by making a test pattern, rotating cap half turn and spraying again. If the defect is inverted, the obstruction is on the air cap. •
Clean the air cap as described.
If the obstruction is on the fluid tip, check for: •
Dried paint inside the opening - wash it off with solvent.
•
Fine burring around the tip - remove the burrs with 600 wet or dry. Heavy Right or Left Side Pattern This is caused by: •
Horn holes partially blocked.
•
Obstruction on fluid tip.
•
One jet blocked on a multi-jet air cap.
To rectify: •
Clean the air cap or the fluid tip.
Heavy Centre Pattern This is caused by: •
Too low a setting of spreader adjustment valve (where fitted).
•
Atomising pressure low, or material too thick.
•
With pressure feed, fluid pressure to high, or material
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flow in excess of the cap's normal capacity. •
Wrong size nozzle for material being used.
To rectify •
If adjustments are unbalanced, readjust atomising pressure, fluid pressure and spray width until correct pattern is obtained. Orange Peel Effect This is a finishing defect common to cellulose and synthetic materials, caused by: •
Improper thinner. - use the correct thinners.
•
Material too thick. - use more thinners.
•
Gun held at an incorrect angle or too close to the surface. - use the correct spray gun technique
•
Too little air pressure - increase air pressure.
Sagging Surface Sags and runs on the sprayed surface are caused by: •
Too much material applied to surface.
•
Gun moved too slowly Increase gun stroke speed.
•
Material too thin. - Use less thinners.
•
Gun held at an incorrect angle or too close to the surface - use the correct spray gun technique.
Striped or Uneven Surface This is caused by: •
Tilting the gun. One side of the pattern its the surface from a shorter distance causing more material to be applied at this point - Use the correct spray gun technique.
•
Air cap or fluid may have dirt or burrs on it. This causes heavy top or bottom spray pattern - Clean or replace the air cap or the fluid tip.
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•
'Split spray' causing more material to be applied at the top and bottom of the pattern - Increase the fluid pressure or decrease the width of the pattern by reducing the atomising pressure.
•
Spray patterns not properly lapped - Use correct spray gun technique.
Blushing Mainly peculiar to lacquer. This is a white cloudy effect on the lacquer coated surface and is caused by: •
High humidity; damp, rainy or foggy weather, or hot, sultry weather.
•
Material manufacturer will advise appropriate retarder thinner and spray in a controlled environment
Blisters, Bubbles and Pinholes This is caused by: •
Moisture or oil in air line - Clean the transformer or use a proper air supply.
•
Thinner incorrect - Use the correct thinners.
•
Too much paint, applied too quickly - Allow earlier coats to dry or flash off between coats. Spray Fog This is caused by:
15.4 Conventional Spray Gun Technique
•
Material too thin.
•
Over-atomisation due to too high an atomising air pressure for the amount of fluid flowing - Adjust the air supply pressure.
•
Improper use of the gun such as incorrect stroking or the gun being held too far from surface - Use the correct spray gun techniques.
A spray gun is a precision air tool with delicate finely machined fittings, holes and passages to transport air and paint through the gun, so that it can be propelled towards a surface in a controlled pattern producing a smooth finish.
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For a spray gun to work properly: •
The air cap and fluid tip must be clean.
•
The pot vent hole in a suction feed gun must be free of dried paint.
•
The paint must be correctly thinned and thoroughly stirred.
•
Air pressure adjusted to the guns specified capacity, generally 300 to 350 kPa.
•
Always test a spray gun prior to use by placing some thinner or thinned paint into the container and spraying it onto a test panel. Strain all paint prior to use and check viscosity of product.
•
Check the fan control for desirable spray fan width.
•
Check the fluid control adjustment for correct atomisation and flow.
A surface can only be spray painted successfully when the painter is comfortable, properly positioned and moves and operates the gun in a correct way The gun must be suitable for the material being used: •
It must be fitted with the correct set-up.
•
It must be adjusted to give a correct material flow.
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Positioning Position yourself comfortably, approximately one arm's length from the surface to be sprayed. •
Spread the feet apart for even balance.
•
Position yourself slightly off centre from the panel to be sprayed giving more area for the spraying hand.
•
Spraying distance is generally only one horizontal stroke length that can be achieved without moving the feet (approx. 1-11/2 metres).
•
Hold the handle of the spray gun between the palm and thumb. The 4th finger and little finger around the handle. Place the index finger and middle finger onto the trigger.
•
Hold the air hose approximately 1 metre from the gun with the other hand, this assists gun balance.
•
Hold the gun at right angles to the surface so that the air cap may travel parallel to the surface.
•
Position the spraying hand so that the air cap is approximately one hand span (150-200 mm) from the spraying surface. The forearm, arm and wrist should be able to be moved across the job so that the gun is equal distance and parallel to the surface at all times.
Correct spraying distance – 150 to 200mm from surface.
15.5 Airless Spray System
The airless spray system requires paint to be placed under pressure and forced out through a tip. The airless principle is like a garden hose. Pressurised water travels through the garden hose and through the restriction in the nozzle, causing the water to atomise as it leaves the nozzle.
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To pressurise the paint airless systems use one of two pumps. These are either piston or diaphragm. The pumps need energy/power source to run and this is supplied by electricity, compressed air or a liquid fuel (petrol, diesel). Depending on where they are to be used, the power supply must be considered. Electricity is usually available but liquid fuels can give independence in remote areas. The pumps on the airless units are the main working component of the system. They require regular maintenance and sometimes repair. Spray tips wear also and need replacing regularly. The tips are made of Tungsten Carbide. Generally keeping oil levels correct, flushing and cleaning the system and inspecting hose lines and power leads, is required for a long, safe, dependable, service life. This maintenance can be carried out by the tradesperson. Repairs should be carried out by a qualified technician.
ADVANTAGES AND DISADVANTAGES OF AIRLESS SPRAY Reduced Bounce-back Because no compressed air is mixed with the material there is less bounce-back than air spray. Therefore, the transfer of material to the surface is more efficient (80-90% of the material will be transferred to the surface). Increased Production Airless spray is faster than conventional spray because it provides a higher film build with one stroke of the gun. A variety of spray tips and fan sizes combined with a wide range of accessories and equipment, help to complete a job faster and more efficiently. A variety of materials can be applied by airless spray.
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Sprays Viscous Materials Due to the high pressure of airless spray, high viscosity materials can be atomised without costly thinning with solvents. Improved Coverage Airless spray will apply a thicker coating more evenly which helps to improve the coverage of the material. Provides an Accurate Spray Pattern Airless spray creates a tight, sharply defined spray pattern which is free of billowing air turbulence. Ease of Handling Airless equipment is portable, with no compressor to transport around. The airless guns are easy to handle because there is no material cup connected to the gun. Disadvantages of Airless Spray •
High initial cost of equipment.
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Cost of replacement parts.
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Setting up and cleaning up time.
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Unsuitable for small jobs.
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Overspray (unpleasant working conditions).
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Mechanical breakdowns (complexities).
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No production (down time).
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Can cause serious injury.
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Unsuitable for use with some types of coatings.
Important! Because airless spray units develop extremely high pressures; fluids under high pressure can penetrate the human skin and cause serious injury, seek IMMEDIATE medical care if an injury occurs. If fluid cuts or penetrates the skin, do not treat as a simple cut. Be ready to tell the doctor exactly what fluid was injected. Airless equipment is high pressure equipment; compare the pressures below: Garden hose: 30 – 60 P.S.I. Car Wash: 300 – 600 P.S.I. High Pressure Washer: 600 P.S.I or more
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Airless Paint Sprayer: 0 – 3500 P.S.I. •
NEVER point the gun at your body or at anyone else.
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NEVER put your hand or fingers in front of the gun.
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NEVER place the tip or gun nozzle in direct contact with any part of the body.
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NEVER leave the gun unattended without releasing the pressure and locking the trigger.
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DO NOT aim the gun at any one person or any part of the body
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DO NOT at anytime place hands or any other portion of the body in front of the spray tip.
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DO NOT alter the equipment in any manner.
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DO NOT use a damaged or weakened airless fluid hose.
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DO NOT operate gun without the trigger guard attached.
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DO NOT leave equipment under pressure unattended for any period of time. - Relieve pressure by shutting off power and opening trigger until all fluid ceases to flow.
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DO NOT operate gun without the tip guard assembly attached.
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DO NOT exceed the maximum operating pressure. The maximum operating pressure is: The pressure of the lowest rated accessory item within the spray system, even though some of the accessories have a higher maximum pressure rating.
WARNING: When the spray nozzle or tip has been removed, an airless gun is still dangerous because a greater volume of liquid can be emitted from the gun outlet at a high velocity. •
ALWAYS shut off power to the pump and relieve fluid pressure from the gun and hose before attempting to remove the tip, gun or any part of the gun.
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ALWAYS set the safety lock in the locked position and shut off the power to the pump when the gun is not in use.
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ALWAYS check the operation of the safety lock before spraying.
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ALWAYS check and tighten all threaded connections carefully.
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ALWAYS check the locknut holding inlet body to gun before spraying.
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•
ALWAYS make sure the spray gun is earthed to prevent static spark, fire or explosion. The high velocity flow of fluids through the hose and tip may develop static electricity. Be sure that the gun is earthed. Check the ground continuity in the hose and connections before spraying.
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ALWAYS use a bare metal container when flushing to avoid static sparking.
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ALWAYS keep the gun and equipment clean.
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ALWAYS spray in a well ventilated area and/or wear a spray mask.
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ALWAYS read the operating manuals carefully before use.
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ALWAYS consult the paint manufacturer prior to spraying any special purpose coating, to ensure that their solvents are compatible with aluminium and zinc parts of the spray unit.
Electrical Extension Cords •
All electrical extension cords must be 3 wire, 15 amp minimum with a 3 wire plug that will plug into a 3 wire, earthed, electrical outlet.
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Do not use two wire extension cords.
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Locate your pump as close to the power supply as possible, to ensure maximum electrical power to your pump.
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The maximum length of all electrical extension cords should not exceed 25 metres.
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Use longer fluid hoses not longer extension cords.
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Electrical extension cords should be protected from vehicle traffic and sharp cutting edges and objects.
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Promptly replace any worn or damaged cords.
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The motor should always be kept clean and dry. Paint acts as an insulator and too much paint on the motor will cause it to overheat.
Filters & Tips There are a number of different models of airless spray units. Some involve using a diaphragm pump while others use a piston pump.
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It is important that you become familiar with the unit you are going to use. Questions you should ask before using any new airless spray unit are: •
What type of pump does this unit use?
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Where are all the filters?
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Does this unit have a manifold filter? (Some airless spray units only have two filters, a gun filter and an inlet strainer.)
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Does this unit require any lubricant and if so where do we apply these?
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What are the limitations of the machine?
With any airless spray unit it is important to know the set up, use, pack up and clean up of the unit. This includes knowing the filter types and sizes, tip sizes and clean up requirements of these.
Tip Sizes Spray tip dimensions determine capability. Selecting the proper spray tip is one of the most important parts of airless spraying. • The tip determines the application rate and spray fan width. • The tip part numbers gives valuable information about its capability.
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Tip sizes are usually indicated by a set of three numbers on the wing of the tip. There are some exceptions to this however the majority of tips indicate the sizes this way. Orifice Size determines how many litres per minute can be atomised through the airless spray tip. The last two digits of the part number tell the orifice size in thousandths of an inc In this example, the orifice is .015” (0.381mm):
Spray Width is based on spraying 12 in. (305 mm) from the surface. •
Double the fourth digit of the tip part number to determine the approximate minimum spray width in inches.
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Add two inches to that number for maximum width.
In this example above, the tip size produces a 8-10” (203 254mm) spray pattern at 12” (305mm) from the surface.
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General Tip Selection Information 1. Determine the maximum flow rate of your spray system. Your spray system (sprayer or pump and power source) must be sized adequately to support the flow rate of the tip you select. 2. Determine the material(s) to be sprayed and the desired flow rate. If your pump is supporting more than one gun, add together the flow rate needed for each gun. 3. Determine the required orifice size on the tip chart. If the total maximum flow rate(s) is compatible with your spray system, select the desired fan width and then order the tip number given in the adjacent column.
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General Tip Recommendations The following tips give good results with the most commonly used architectural and maintenance coatings. For the best results spraying on flat surfaces, an 8-10” or 10-12” (203 254 or 254 - 305mm) spray fan width is recommended. The actual spray gun tip distance from the surface and the tip fan width will affect the spray pattern and therefore the finished appearance of the coating.
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Examples of the correct matching of distance and fan width are detailed below:
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16 Apply Stains & Clear Timber Finishes
16.0 Introduction
16.0 Preparing Timber for clear finishes
A professional looking finish depends on how well you prepare the timber. Inadequate preparation, especially sanding can result in a rough, patchy finish. Timber needs careful preparation to remove scratches and imperfections. Surfaces can be prepared using a number of techniques depending on the surface and the finish required. In all cases you must complete a pre-check and rectify any faults. Doing a pre-check and rectifying faults will allow you the opportunity to fix problems before you get to the fine finish you will require. Pre-Check Timber surfaces need to be checked for any glue residue before beginning to finish. The best way to find any glue marks is to wipe the surface with a damp rag or sponge. The liquid can be a clean solvent or water. Water is commonly used as it is inexpensive and easily accessed, removes any water stains and raises the grain in the timber surface giving a smoother surface once sanded. Methylated spirits also raises the grain however turpentine or thinners do not. Making the surface damp will show up any defects, particularly glue residue that is not visible when dry. If any defects are found, gently circle them with a pencil mark. Once you have found all defects you can begin to rectify them. For repairs of timber refer to chapter 13 of this book.
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Bleaching timber Natural timbers often become stained by water or rust marks prior to clear finishing. These marks are highlighted by the clear finish and look quite ugly. A common problem is around a nail which has rusted because of water and the stain spreads into the surrounding surface. These stains are removed prior to coating with Oxalic Acid bleach. Timbers which are darker than required or have a dark panel which is different to others and looks odd can also be lightened by bleaching with Oxalic Acid. Please note •
Failure to remove all traces of acid may result in discolouration of the clear finish or timber stain.
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Small areas may be patched with a cotton bud or material soaked in the bleaching solution.
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Repeat the application if marks are stubborn.
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Water and bleach will swell and raise the grain.
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When dry sand the timber until smooth with fine abrasive paper always along the grain.
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Always wear a dust mask when sanding bleached timber.
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Allow the surface to dry thoroughly before sanding.
Other bleaches are available to the painter and will do the task well, such as Hydrogen Peroxide and Ammonia. These are a little difficult to master and are quite toxic. Household bleach used full strength may also be used when staining is mild. This is not as effective as oxalic acid.
16.2 Stopping & Filling
Stopping Stopping is the process of filling nail holes, surface holes and cracks in the timber. Ready mixed materials for this process are available, some of which can be purchased in wood colours. Filling Filling is for the pores (open grain) in timber, it is a thick creamy consistency. Many timbers have open grain (pores) in their surface which are emphasised with clear finishing. If a mirror smooth finish is required, it is very difficult to obtain such a finish if the open grain pores are not filled prior to coating.
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The open grain appearance is often preferred as a finish; grain filling is only carried out when requested. There are two types of wood grain fillers: 1. Water Based Filler; and 2. Oil Based Filler. WATER BASED FILLERS Used for stopping or filling direct to bare timber, interior architraves, doors and paneling. Advantage Is a fast drying, hard setting, easy to sand interior filler. Can be stained or is available in a variety of timber matching colours. Disadvantage Not suitable for exterior surfaces. Application Apply by stiff brush, hessian or open weave rag, wipe off excess filler across the grain. Allow to dry and sand thoroughly with fine abrasive paper. Applied also with a filling blade, with and across the grain, remove all excess filler. Allow to dry and sand smooth. Can be coated over with water or oil based, one or two pack polyurethane clear. SYNTHETIC FILLERS (Body Filler, Fibre Glass Filler; and Epoxy Filler) Used for interior and exterior repairing of bare timber prior to staining; can be tinted to match the required finish using universal tinters. Advantages There is a large range of fast drying hard, stopping materials that cures to a very hard finish.
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Disadvantages More difficult to use Application Manufacturer’s instructions must be strictly followed.
16.3 Stains
Wood stains colour the timber and highlight the natural grain giving common timbers a quality appearance. •
Wood stains should always be applied to bare timber.
•
Wood stains are for timber colour only and in most cases does not provide any lasting protection to timber surfaces.
•
Semi-transparent or opaque stains, containing antifungicides, are used on external surfaces.
Timber stains may be water, oil or solvent based. You can stain and coat a timber in one application with a stain finish. Stains designed to change the colour of the wood only. Stains contain either dyes or pigments, solvent to carry the product into the wood and a small amount of resin or binder to bind the colour to the wood fibre. Pigments are better for light fastness; dyes are cleaner in colour. Combination Stain and Oil, some products combine the protection of the oil and the colour effect of the stain. These products are certainly step savers, since two functions are achieved in one step. Stains and penetrating oils are designed to dry inside the wood fibres, they do not dry well on the wood surface; always wipe the wood totally clean with rags.
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16.4 Clear Finishes
Penetrating products leave the wood more natural than the film forming products. However film forming products seal off the wood and provide greater protection against water, chemicals, wear and destructive effect of sunlight. Currently the three most popular products that protect the wood with a thin film are: Clear Lacquers Most lacquers on the market are Nitro-Cellulose lacquers. Lacquers dry by solvent evaporation only. They remain soluble in the lacquer solvent. As a result the lacquers have the advantage that application of another coat "bites" in the previous coat and intercoat adhesion is always perfect. It also makes repair and polishing easy.
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Varnishes This group represents all clear products that dry by oxidation (oxygen from the air causes the resin to dry). The most popular types are Polyurethane Varnishes. Water based clears This group of products is growing, due to the low odour and low flammability. During the last few years these products have been greatly improved. Since they are low odour, not combustible or flammable, it is certainly recommended that you try these on some wood finishing jobs. Oils (often referred to as Danish Oil) that penetrate the top layer of the wood fibres and after drying protect the wood fibres against the degradation from light, water and other hazards. These products contain oil (Linseed oil, China Wood Oil), driers and solvents. The driers speed up the drying of the oil. Interior finishes The following list details the types of clear finishes available, together with their advantages and •
limitations:
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Polyurethane
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Water Based Clear Coatings
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Varnishes
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Nitro-Cellulose Lacquer
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Shellac
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Plastics
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Translucent Finishes
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Sanding Sealer
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Exterior Finishes
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17 Wallpaper
17.0 Properties of Wallpaper
There are many different types of wall coverings available. Wallpaper is manufactured by a printing process similar to printing fabrics, such as curtains. It is supplied in rolls that are trimmed on each edge and ready for use. The most common types available are supplied in rolls 10 metres long which are 500 mm to 530 mm wide. Wall Coverings Can Be Pre-Pasted Or Un-Pasted. Pre-Pasted - These wall coverings have adhesive (paste) applied by the manufacturer, in powder form, on the back. You need only to dip the paper into water to soften or reactivate the adhesive, then, to pull it out and apply to the wall. Un-Pasted - These wall coverings require an adhesive to be applied, this is called paste. The paper hanger would normally apply the paste to the back of the paper by brush, however rollers or pasting machines are also used. Common Wallpaper Types •
Regular Wallpaper (made from paper only, Simplex and Embossed)
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Vinyl Coated Wallpaper
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Vinyl Wallcovering
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Metallic Foils
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Textiles: Flocks, Grassweaves, Melded Fabrics
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Hand Printed Papers
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Murals
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Borders
Although not all these types of wallcovering are still sold, the tradesperson may be called upon to strip (remove) these types in readiness for new wallcovering or paint. Following is a list and description of both Domestic and Commercial types of
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Wallcoverings. In being able to recognise these different types it will be possible to know how to strip them and handle their individual characteristics when applying them. Regular Wallpaper
These are the fore runners of the modern vinyl wallcovering. They are simply paper with printed colours. Recommended size - Latex or cellulose. Recommended adhesive - Latex or starch types. General remarks •
Do not over soak.
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Not suitable for ‘wet’ areas such as bathrooms, laundries.
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Can be coated with a glaze to make washable.
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Available as pre-pasted.
Duplex Embossed & Anaglypta Wallpaper
Some wallpapers are dual layer with a pattern stamped into them to provide a profile (embossed). Some embossed papers called Anaglypta is designed to be painted over to give colour and wear resistance.
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Recommended size - Latex or cellulose. Recommended adhesive - Wheaten starch. General remarks •
Soak until supple after thickly pasting.
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Do not flatten the embossed pattern.
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Do not use a seam roller on joins.
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Take care to remove all air bubbles during application.
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Remove any paste from the surface particularly at joins.
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Sometimes available as pre-pasted requires additional soaking time.
Vinyl Coated Wallpaper
These are harder wearing than straight papers as they have a clear PVA coating over their face. This does make them hard to strip since water cannot penetrate the face to soak the backing. Recommended size - Latex or cellulose. Recommended adhesive - Mostly pre-pasted otherwise latex or fungus resistant starch type adhesives. General remarks •
Use a ‘stick back’ or also known as ‘lap adhesive’ (PVA) adhesive when overlapping in corners.
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Suitable for all areas.
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Difficult to remove.
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Paper is often thin and shiny, requires good surface preparation.
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Vinyl Wallpaper
This term applies to a continuous strip of polyvinyl chloride (PVC) to which a paper or fabric backing has been laminated for ease of application. Un-backed solid vinyl sheeting is also available used in commercial applications because of its hard wearing properties. Recommended size - Latex. Recommended adhesive - Mostly pre-pasted otherwise latex or fungus resistant starch type adhesive. General remarks •
Very strong and durable allows for confident hanging and trimming.
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Use a ‘stick back’ adhesive such as PVA joiners glue when overlapping in corners.
•
Pre-pasted or latex adhesives will not stick vinyl to vinyl.
Pre-pasted Soaking time will vary from paper to paper requiring longer on some heavy vinyls. This may also cause edge drying. Additional adhesive may be needed and applied by brush.
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Metallic Foils
These wallcoverings have a reflective surface, consisting of an extremely thin layer; aluminium, laminated to a paper backing. Foils may be plain or have an overpattern: design applied. Take care around power outlets as the foil conducts electricity. Textiles: Flocks
These wallcoverings have a velvety pile, forming a pattern, which stands out in relief from the covering.
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The pattern design is printed using an adhesive rather than a pigment. Fibres are dusted onto the covering and adhere to the adhesive which forms the pattern. Flock wallcoverings are available as vinyls or papers and can be pre-pasted or unpasted.
Textiles: Grassweaves
Sometimes referred to as 'grasspaper'; are woven materials such as natural grasses, seaweed, wood pulp and silk which are dyed and glued to a thin paper backing. Grassweaves are always supplied un-pasted.
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Textiles – Melded Fabrics
These wallcoverings include natural fibres and synthetic fibres. The width and length of rolls may vary between different fabrics. Some examples of fabric wallcoverings are; Suede, with a cloth, paper or fibre glass backing, Hessian, in various widths and colours, also available with a paper backing. Silk and velvet (paper backed and cloth backed in the case of synthetic velvet). 'Front Runner1 - An unbacked fabric comprising of nylon and polyester fibres. Where fabrics are supplied with a paper backing, they are usually pre-trimmed ready for hanging. Hand Printed Papers There are manufacturers who make small quantities of specified papers for interior decorators and architects to supply clients who want a 'custom made' wallcovering. The most common method of manufacture is by screen printing the design using latex paints and inks. These papers are normally un-pasted and supplied with a selvedge.
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Murals & Photo-Walls
This type of wallcovering is designed for use on feature walls. They are usually purchased pre-trimmed and pre-cut into rectangular sections ready to apply to the prepared wall surface. Each section is identified with a number or letter printed oh the back. Murals can be printed on paper, vinyl or fabric or photographically reproduced onto those materials. Borders
This wallcovering comes as a narrow strip with a regular repeating pattern. They are generally applied horizontally below the cornice, at picture rail height or at chair rail height. They can be applied as a companion with other wallcoverings or used to set off a painted room. Some are ready-pasted and require passing through a trough of water and others use a permanently sticky contact adhesive to hold them in place. Depending on the contact made with the room’s inhabitants they can be bonded directly on top of the other wallcovering or in-laid for better serviceability. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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17.1 Label Information
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Check Batch Numbers In machine printing all the wallpaper rolls cut from a continuous ‘run’ are identical in colour. The colours in earlier or later ‘runs’ may vary slightly. Therefore manufacturers label each roll with a number. These numbers are often referred to as batch numbers, lot numbers, run numbers or shade numbers. These numbers should match on all rolls to be used in one area. Rolls with different numbers used together may be different in colour and/or shade. If hung, this could lead to an unacceptable job which may have to be re-done at the paper hangers own expense. The label below clearly shows the batch number, referred to as 'lot number' on this particular wallpaper label.
17.2 Prepare the area
The following information is from NSW TAFE Australia. Before you apply wallpaper, you need to first set up a storage area and prepare your work area. Set up a storage area To ensure the safety of yourself and others and to give yourself the maximum space possible in the actual room you’re going to be working in, you should set up a separate storage area.
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Make sure that the storage area: •
has good ventilation and light
•
is neither too hot nor too cold
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is large enough to easily hold all materials and equipment
•
is close to the area you’re actually going to be working in
Prepare the storage area by: •
covering the floor with protective drop sheets (doubled up so that they’re thick)
•
storing materials AWAY from the equipment to prevent any accidents
•
placing all equipment and material so they’re easily accessible
•
storing any inflammable materials in an area where they can’t easily be tipped over or damaged. MAKE SURE that they are NOT near any source of heat or naked flame.
Set up your work area
You need to set up the area you’re actually going to be working in as well! Remove / Protect furniture and other items: •
Remove any furniture and other items that could be damaged or obstruct your ability to work safely and effectively. This includes removing ornaments, pictures, window dressings or any other decorative items. Store furniture and these other items safely in another area.
•
If furniture cannot be removed from the room then you should move it into the centre of the area you’ll be working in and cover it to keep it from being damaged.
•
Cover all floor coverings (like carpet, polished floors, tiles, etc.) with drop sheets. Use plastic drop sheets if possible to keep the area as dry as possible as water and old adhesive and size will drip onto the floor as you’re working.
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Remove / Protect fittings and fixtures What are fittings? Fittings and fixtures include the following: •
light shades
•
window fittings
•
wall brackets
To prevent fittings from being damaged, you should do the following: •
Remove them (usually using a screwdriver)
•
If they cannot be removed, protect them by covering them with masking tape or by placing plastic bags over them.
•
Place fittings and screws that have been removed in a safe place to prevent loose parts from being lost.
WARNING: DO NOT interfere with or remove ANY ELECTRICAL FITTINGS! Cover electrical fittings with masking tape.
17.4 Size & Adhesives
After you’ve prepared and sealed your surface, you need to apply wall-size to the surface before you can hang your paper. Size is used because it: •
provides an improved key to bond the paper to the wall surface
•
slows down the absorption of the wallpaper paste into the wall surface
•
provides a longer working time with the paper, making it easier to slip and slide the paper into place.
Important: The usual trade practice is to size one day then hang the lining paper the next day. If you leave size for days or weeks before the lining is applied, it may harden and become quite 'glassy' and repel moisture. Applying size Cellulose or Latex size can be used. We’re going to look at applying a cellulose size to the wall surface. Always check and follow the manufacturer’s instructions for preparing size.
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Safety first! Fungicide protected size is TOXIC and you must not inhale dust during the mixing process. Remember your PPE. You should •
wear a dust mask
•
do NOT lean over the bucket during the mixing process
•
avoid getting the size on your skin.
Generally, these are the steps you’d follow to prepare the wall size: •
sprinkle the powder into lukewarm water
•
avoid lumps by continuously stirring with a whisk while you’re adding the powder
•
leave the size to stand for the recommended time so it can thicken (usually about 20 minutes or so)
•
before you apply the size to the wall, give it a final stir with the whisk to ensure a smooth, even mix. Note: The size should be free flowing and easy to apply.
Types of Size Many brands and varieties of sizes are available, however, they all belong to one of three types: Latex This size is recommended by most manufacturers for all type of wall coverings, surface conditions and substrates. This type of size/adhesive is the most widely used because it is ready mixed, ‘universal’, strong, and is compatible with latex adhesives which are also widely used for hanging wall coverings. Latex size is particularly suitable for application on satin and gloss painted surfaces because of its adhesive qualities. Cellulose Provided as a powder and mixed with water. These sizes are recommended for use on sealed, previously painted surfaces. They are not recommended for use on satin or gloss enamel surfaces (other products are better suited). Starch/Ether These types of sizes are sold as ‘universal’ sizes for use on all sealed surfaces and under all types of wall coverings. They are sold in powder form and are mixed with water.
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WALLPAPER ADHESIVES It is extremely important that the correct adhesive be used for satisfactory results in paper hanging. Types of Adhesives Pastes and adhesives can be divided into five different types. Adhesives can be ready mixed or in powder form which require mixing in water. Wheaten Starch Paste This paste is recommended for all papers that are not impervious to water, that is, papers that are not washable. It is especially suitable for heavy duplex-type embossed papers. It is high solid, low water-type paste which allows adequate ‘soaking time’ for paper fibres to expand. Starch Ether Paste The most general purpose paste of all. It is suitable for all papers in the basic paper range. Ready-Mixed Fungicidal Adhesive (Latex) This adhesive is extra ‘tacky’ and has additional adhesive qualities. Although more expensive, it is suitable for all papers except heavy embossed duplex papers. During hot weather, add 10% water to retain the limited ‘slip’ ability. Cellulose Paste This paste is a low solid, high water content material and must not be over thinned. Caution must be taken in hot or dry weather as rapid drying will occur, resulting in a lack of adhesion. Cellulose paste is not suitable for heavyweight papers as the low solid content will be quickly absorbed, resulting in a loss of adhesion. This paste should be liberally applied and used only on lightweight papers. Fungus-Resistant Paste This paste contains a fungicidal agent and therefore is suitable for use on papers which are impervious to water, example plastic-coated paper, solid vinyl (paper backed).
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Powder Powder-type type paste should be mixed only in accordance with the ma manufacturer’s directions. •
mix in a clean bucket or container;
•
mix only enough for 24 hours use;
•
follow mixing instructions carefully to avoid lumps of paste; and
•
do not over thin.
NOTE: Some pastes can produce mould growth, have low adhesion, or can tarnis tarnish h and discolour some papers. Follow instructions and choose only the correct paste for the paper being hung, example fungus resistant paste to avoid mould growth. Adhesive must be removed from surrounding paintwork as it will stain and damage in a short ti time me if left, requiring repainting. Most pastes and adhesives contain chemicals which can be harmful to skin and general health. Do not inhale fumes - wash hands regularly.
17.5 Wallpaper Application
Realistically the best way to learn how to apply wallpaper is by being shown practically and practicing yourself. Your trainer will provide suitable arrangements for you to do this. Tools and materials Before you begin, you’ll need to select the right tools and materials for the job. You’ll need:
p sheet to protect a drop surfaces
a trestle or stepladder
a spirit level
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a lay brush
a sponge
Scissors (known as shears in the trade)
and a pencil
a bucket of water.
a paperhanger’s apron to hold your tools
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a plumb bob
a steel measuring tape, a ruler
pasting table
a pasting brush
a trimming guide and trimming knife
seam roller
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18 Graffiti & Prevention
18.0 Introduction
Graffiti, as we know it, is a recent phenomenon, which started in New York City in the 1960’s. The first recognised graffiti artist, (or bomber), was “TAKI 183”, a Courier/Delivery Man living on 183rd Street, who tagged in every location he happened to go to. Graffiti can be defined as: DRAWINGS, OR WRITING, APPLIED BY VARIOUS METHODS, USING VARIOUS MEDIUMS, TO A SURFACE These drawings or words can be artistic, obscene, or political, and are applied in public places, or in areas easily seen, e.g. public parks, public toilets, underpasses, railway lines, main roads, and private fences and walls. wall The dictionary definition is as follows: Graffiti: (Italian, from graffio a scratch from Greek graphein mark, draw, write) Archaeol. An ancient drawing or writing scratched on a wall or other surface. Drawings or words, sometimes obscene, sometimes political poli etc., written on the walls of public toilets but often elsewhere, as on bill boards, walls of buildings etc. There are three types of Graffiti: 1. - “The tag”, which is opportunist graffiti, is applied very quickly using felt pens, spray cans, etc., and usually consists of initials, word outline, geometric outline, and performed by youths with an amount of peer group pressure.
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2. -“Throw “Throw up”, usually a bubble outline using spray, is slower to produce than a tag and is sometimes filled in at a later date by the “want to be graffiti artists”.
3. - “The piece”, or “Masterpiece”, which is usually quite large and multi multi-coloured, is slow to produce and performed by hard core graffiti artists aged between late teens to twenties, and sometimes older. The “throw up” or “piece” are both premeditated, generally with sketches and colour combinations determined before any application is att attempted. empted. This type of graffiti is organised in gangs by experienced, mature artists. Although graffiti may, in some circles, be regarded as an art form, there is a direct correlation between crime and graffiti sub-culture, culture, and it is widely considered as vandalism. van There are numerous ideas on what actually motivates graffiti artists. Psychologists suggest some of the following reasons: reasons:-
18.1 Graffiti Removal
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Boredom
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Recognition
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Sexual factors
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Peer group pressure
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Self expression
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Political
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Territorial
There is no single preferred method for the removal of graffiti; however, it is best to use the least severe of the successful methods.
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For graffiti of uncertain composition, washing with water and a mild detergent may suffice. Alternatively, in increasing severity, mineral turps, toluene, a proprietary graffiti remover, a paint stripper, or caustic paint remover may be necessary. Every attempt should be made to remove the graffiti as soon as possible after it has been applied; the longer it is left to cure the more difficult it will be to remove. The technique for removal is also crucial, as the graffiti needs to be removed as soon as it has been sufficiently softened by the solvent to be flushed from the surface. If left too long, the solvent may cause the graffiti to penetrate deeper into the surface leaving a shadow. Care needs to be taken when handling organic graffiti strippers. Hazards caused by flammability, contact with skin and eyes and the inhalation of vapour need to be recognized. Caustic strippers are hazardous and also injurious to some metals, notably aluminium and zinc.
18.2 Anti Graffiti Paints
A pigmented or clear paint finish applied to a surface either to inhibit its defacement by graffiti by virtue of its impervious or sacrificial nature, or enable the graffiti or the paint film to be readily removed. Graffiti may be managed by the application of anti-graffiti paints or by overpainting. Graffiti may be successfully overpainted provided that the graffiti is not solubilized by the solvents in the paint. Thus latex paints may be successfully used over water insoluble stains. Overpainting is commonly the most cost effective means of managing graffiti and avoids the use of harmful chemicals. Surface vulnerability Selection of the substrate material is most important for minimizing the problem of graffiti. A smooth impervious surface, such as glass or stainless steel, has particular advantages, since removal of graffiti may be achieved by using the strongest organic solvents without detriment to the substrate.
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In addition, the graffiti will not become ingrained as it does on a more absorbent surface. After a smooth impervious surface, the next most suitable class of substrate is a smooth painted surface. The use of anti-graffiti coatings on rough or textured surfaces presents a far more serious problem, for the following reasons: (a) Even with multiple coats, traditional coatings cannot reasonably be applied over rough surfaces, without the formation of pinholes or points where the film thickness is extremely low. At such points, graffiti is able to penetrate to the substrate and resist subsequent removal methods. (b) Graffiti removal material is difficult to apply evenly over rough surfaces. Surface colour is a consideration for discouraging the application of graffiti. Mid-tones are less attractive to graffiti artists than a white or pastel surface, while multicoloured patterns are also helpful in camouflaging the appearance of the attack. Types of ant-graffiti paints There are essentially two types of products: 1. ‘permanent’ coatings(non-sacrifical), which are readily cleaned free of graffiti, 2.
and ‘temporary’ types(sacrificial), which are readily removed with any graffiti.
Due to the large variety of proprietary products available, manufacturers’ advice should be sought on the ease of repainting after the original coating has been weathered or damaged. Non sacrificial coatings Only some two-pack pigmented polyurethane paints and two-pack pigmented waterborne epoxy resins are suitable for extended durability performance, although a significantly shorter service life, perhaps of three years, may be anticipated for clear two-pack polyurethanes and chalking is more rapid with two-pack epoxy resins. For interior service, selected two-pack solvent-borne epoxy enamels, single pack moisture-cured urethanes and twopack epoxy acrylics are also appropriate. Non-sacrificial systems must be viewed as systems which, not only include the paint, but also the specific removal Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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agent for example: •
Ameron “PSX 700” – Paint
•
Ameron “Graffi Green” – Range of removal products
Sacrificial coatings Sacrificial coatings are removed from the surface with the graffiti when the surface is cleaned. These are usually in the form of a wax base and are clear in appearance. They are generally used on face masonry, e.g. brick or stone, and sometimes on pre-finished substrates, e.g. Colorbond, the principle being that, having been graffitied, the offending areas can easily be removed by washing with solvent, chemical, high pressure hot water, or a combination of these procedures. Removing graffiti from a sacrificial coating, results in the coating being fully, or partially, removed. These areas must then be re-coated with the same product to ensure continuation of optimum performance. An example of this type of product is “Wattyl Graffiti Barrier”
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19 Industrial Coatings
19.0 Corrosion
Corrosion is usually referred to as the degradation of the metal by chemical or electro-chemical reaction with its environment. When considered broadly, corrosion may be looked upon as the tendency of the metal to revert to its natural state similar to the oxide from which it was originally smelted. The actual mechanism in the corrosion of iron and steel is extremely complex and embraces the fields of chemistry and electro-chemistry. Corrosion is classified into two main types: 1. Atmospheric corrosion 2. Galvanised corrosion Atmospheric Corrosion
Metals will corrode when they are exposed to water and oxygen. An electric current will move between different sections of the same piece of metal. These sections of the metal are called anodes (the reactive parts) and cathodes (the lesser active parts). The current flows through an electrolyte (water).
If the water contains dissolved salts such as in seawater the transfer of the current is made easier and the extent of corrosion is increased. An electric current can also pass from one type of metal to another through an electrolyte this is called galvanised corrosion.
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Galvanic Corrosion When two metals come into contact in the presence of water one metal will corrode first and ‘sacrifice’ itself for the other.
In this picture you can see where a steel plate has been bolted to an aluminium substrate causing galvanic corrosion to the aluminium.
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There is a list of metals called the galvanic series of metals, which list metals according to their tendency to corrode when in contact with another metal and water. Metals that are more anodic than other metals will sacrifice itself to the metal that is more cathode.
Note: the further apart on the list the two metals are the faster the corrosion process. The closer the metals are on the list, the slower the corrosion process.
19.1 Durability Considerations
Any coating system has a much shorter life span then the structure itself. As such it is expected that the coating system will be a ‘maintenance coating system’. This means that the coating system will need to be recoated and even likely removed over a period of time. The better the Coating system the longer it will last. Usually the better coating system will be the system that is more thorough in terms of preparation, application and the coating itself.
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As the protection provided by the coating systems covered by this Standard is usually shorter than the expected service life of the structure, due consideration should be given to maintenance or renewal requirements at the planning and design stage. This Standard expresses durability in terms of the following five ranges: •
Short term: 2 to 5 years
•
Medium term: 5 to 10 years
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Long term: 10 to 15 years
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Very long term: 15 to 25 years
•
Extra long term: 25+ years
Because the durability of many coatings may be considerably longer than 25 years, the advice of the coating supplier should be sought. Durability is expressed in terms of coating life to first major maintenance, assuming that the coating has been applied according to the requirements of this and other appropriate Standards, and to the recommendations of the coating manufacturer. It is stressed that the durability range is not a ‘guarantee time’. Durability is a technical consideration that can help the owner set up a maintenance program.
19.2 Classification of environment
The environment can affect both the steel and the paint system. Of prime importance is the effect the environment has on the corrosion of steel. Microclimatic influences Another factor contributing to the corrosion of metals is the local environment or what is called the microclimatic situation. For example water puddling up on steel, or areas where dust and salt can build up if you are near the ocean.
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Examples of microclimatic environments that can accelerate corrosion: •
Where metal may remain damp because of shaded areas
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Where metal remains in water for extended periods
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Where there is going to be surface contamination from salt and dust etc
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If the metal is not freely drained
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Acidic and alkaline fall out from nearby industry
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Where metal is exposed to chemicals and solvents that do not get washed off properly
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Airborne fertilisers
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Transport contamination i.e. Carbons from automobiles
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Surfaces exposed to abrasion and impact
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Surfaces that are too hot or too cold
As a result of microclimatic effects it is very difficult, if not impossible, to predict accurately the aggressiveness of a given environment. So you will need to use a little educated judgment in many circumstances. Atmospheric classifications (applicable to steel) The Australian standards (AS/NZS 2312:1994 – Section 2) list 6 atmospheric classifications. The six classifications are as follows: a) Mild: (ISO Category 2) A mild environment will corrode mild steel at a rate of up to 10µm per year and includes all areas remote from the coast, industrial activity and the tropics. b) Moderate (ISO Category 2) A moderate environment will cause a first year corrosion rate of mild steel of 10 µm to 25 µm and includes areas with light industrial pollution or very light marine influence, or both. c) Tropical (ISO Category 2) A tropical environment includes coastal areas of north Queensland, Northern Territory, north-west Western Australia, Papua-New Guinea and the Pacific Islands, except where directly affected by salt spray. Although corrosivity is generally low in tropical regions, the aggressiveness of the environment to organic coatings Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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means special protection is required. d) Industrial (ISO Category 3-4) Industrial environments will cause a first year corrosion rate of mild steel to be greater than 25 µm. The only areas within this category are around major industrial complexes. e) Marine (ISO Category 3) Marine environments will cause a first year corrosion rate of mild steel of 25 µm to 50 µm and include areas influenced to a moderate extent by coastal salts. f) Severe Marine (ISO Category 4-5) Severe marine environments have high to very high corrosivity and will cause a one year corrosion rate of steel to be in excess of 50 µm. Immersion environments have very high corrosivity and are influenced by type, temperature, concentration and various other factors. The types may include potable (drinking) water, fresh water, seawater, wastewater, oil and refined oil products and chemicals. Specific protection is essential, requiring a high performance coating system and surface preparation is crucial to the life of the system. The application of cathodic protection to the structure must also be considered. Buried environments have very high corrosivity and are influenced by soil type, resistivity, salt and water content, presence of rocks and many other factors. Coating systems must be resistant to soil and rock damage through soil movement and immersion conditions where the structure is near or below the water table. The application of cathodic protection to the structure must also be considered.
19.3 Design Considerations
As a painter you may have no say in the design of a substrate. However, you do have a responsibility to prepare the substrate taking into consideration the design in oder to maximise the coatings performance. For instance if the design allows for moisture to enter in between two plates of metal then use of an appropriate penetrating oil to go between the plates and sealing the plates to prevent moisture could greatly extend the life of the metal.
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19.4 Protective Coatings
Functional properties of individual coats The purpose of coating systems is to form a barrier between the substrate and the damaging condition that the substrate will be exposed to. We may use more than one type of coat for aesthetic reasons or performance reasons.
Note: The elements that contribute to the corrosion process are called the ionic environment Generally the protective coating system is broken into the following categories: •
Primers
•
Sealers
•
Undercoats
•
Build coats
•
Top coats
Here is a brief description of each: Primers The best way to describe the primer coat is that it is the preparation coat. In industrial coating systems it has two main functions: 1. Anti corrosive protection 2. Assisting adhesion Anti-corrosive properties of primers rely on the presence of inhibitive pigments, such pigments may include Zinc or Lead. These coatings should provide protection during the application and the maintenance of the paint system. In other words, if the primer does its job and if maintenance is carried out regularly, then this will reduce the need to remove rust from the substrate.
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Primers applied at the right dry film thickness will protect the substrate from rust creeping in under the coat if there is any damage to the finishing coats. The primer will provide excellent adhesion for final coats as long as the following has been carried out: •
Preparation is carried out properly like the surface sufficiently roughened, cleaned
•
Old coatings are sound
Sealers Sealers are designed to act as barriers and assist the primers do their job. The characteristics of sealer are: •
Provide good inter-coat adhesion
•
Reduces or delays moisture penetration
•
Decreases permeability to oxygen
•
Improves strength
Another important key feature of the sealer is that it often incorporates pigments such as aluminium flakes, talc or iron oxide that operate as a laminate or hard skin layer, providing strength. The sealer can also improve penetration of the binder in a porous substrate; this will prevent the finish coating getting air pockets under the surface leading to the finishing coat popping. Such a popping effect will occur on top of zinc rich coatings. Build coats Build coats are intermediate coatings that provide extra protection through increasing thickness; this will reduce or delay moisture penetration and decrease the permeability of oxidation. Topcoats The topcoat is the aesthetic component of the protective coating system, giving the required colour and gloss level. But it also plays an important role in the overall protection. The topcoat is the first line of defence; it will provide resistance against the weather, sunlight, condensation, impact, abrasion and chemical attack. The cost will have an effect on the dry film thickness, however the higher the build the better the resistance. Reference Material CPC30608 v1.2.docx – Last amended 13/01/2011
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Sometimes topcoats will have special properties for instance: •
Non skid surface for safety reasons
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Self cleaning in kitchens etc
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Chemical resistant specifically for either alkaline or acid
•
Smoother surface for hygiene reasons in order to avoid bacteria settlement
Coating compatibility Another important aspect for composing a maintenance system is the compatibility of the products you are using with the existing coats. Below is a table that will give you a quick basic glance at products that are not compatible over each other.
Also consideration should be given when applying solvent borne paints over tar-based or bituminous coatings; this may result in tar bleeding effects. The effect the environment has on the life of the paint system is also important. The result the environment has on the steel may be different to the outcome that the environment has on the coating. Tropical environments, with high humidity, rainfall, and which promote mould and fungal growth, are far more aggressive to organic coatings than the corrosion rate would suggest.
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Furthermore, the colour of the paint may influence its performance in some environments. Structural considerations There are a number of considerations to be made with regard to the structural situation; for instance: Very fast drying paints are not suitable to spray complex structures because of possible dry spray and build up of too high- dry film thickness. Water borne paints should not be used when ventilation conditions are not good or when the atmospheric conditions are cold and humid. Protection of iron and steel by painting The rate of corrosion of steel depends on current flow between the anodic and cathodic areas. To inhibit corrosion it is therefore necessary to stop or at least reduce this flow of current. Suppressing either the reaction at the cathode or at the anode by inserting a high resistance between these electrodes can do this. For a paint coating to stop this reaction, it must either be impermeable to oxygen and water or impervious to electron flow. Unfortunately paint coatings do not meet these conditions and are sufficiently permeable that they cannot altogether restrain the cathodic reaction. This reaction can be inhibited in either of two ways 1. Make the potential of the iron sufficiently negative so that iron ions are not able to leave the surface. This is commonly referred to as cathodic protection. 2. Cover the surface of the iron with a film that is impervious to the iron ions - this will prevent the ions from going into solution. This is referred to as anodic passivation. Cathodic protection In making the steel more negative, a supply of electrons must be received from another source. Some paints containing metallic pigments are capable of doing this. Certain conditions however have to be met - the metallic particles must be in electrical contact with each other and must be less noble than the steel.
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Anodic passivation When a piece of cleaned iron or steel is exposed to air it almost immediately becomes coated with an invisible oxide film. On contact with water or moisture in the atmosphere this film breaks down, allowing corrosion to occur. Specialised anti-corrosive paint coatings may be used to inhibit this corrosion - they may act in either of two ways: 1. Passivate the surface by means of an inhibitor of limited solubility such as zinc phosphate Or 2. Passivate the surface by means of soaps formed when basic pigments are ground in binders. These soaps oxidise in the presence of water and oxygen, yielding soluble inhibiting compounds Although we have stated previously that all paint films are to some extent permeable to water and oxygen, and that they cannot protect only by impermeability cannot pass through), they do, in spite of this and provide protection to steel by resistance inhibition. It appears that they protect by virtue of their high ionic resistance which stops the movement of ions, therefore reducing corrosion current. They therefore act as a barrier coating, significantly restricting corrosive ions from reaching the metal surface. Paint coatings certainly play a most important part in the science of corrosion control.
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20 Manage Lead and Asbestos Hazards
20.0 Introduction
As a painter you will be required to work with asbestos and lead hazards from time to time. The risk is not only to yourself but also to others around you. So you have a duty of care to control these hazards to reduce the risk
20.1 Health Effects
Lead Lead is a hazardous substance. It can be breathed in or it can be swallowed in the form of paint chips, dust or dirt containing lead or in drinking water or in food. High lead blood levels can have very serious health consequences. Some studies point to possible health consequences to children from low levels of lead in the blood. Very young children would be particularly vulnerable to these potential adverse health effects of elevated levels of lead in the blood. Children absorb the lead mostly by eating it or by touching contaminated dust or soil and then putting their fingers into their mouths. Unnecessary exposure of children to lead should be eliminated as a precautionary measure. Asbestos Asbestos is a hazardous substance. It is a risk to your health and the health of those around you if asbestos fibres become airborne. Three diseases are related clearly to asbestos exposure: 1. Asbestosis - which is a nonmalignant, diffuse fibrosis (scarring) of the lung tissue. It is invariably of occupational origin, usually following many years of exposure. 2. Lung Cancer - has been associated with all forms of
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asbestos. It typically presents 10 - 30 years or longer after the onset of exposure. 3. Mesothelioma – is a highly malignant tumour mour of the tissue membrane which lines the internal organs. When it occurs around the lungs, it is termed pleural mesothelioma.
20.2 Testing Paint for Lead
Lead test kits’ using field test reagents. These economical test kits (pink sticks). They compri comprise two chemical solutions - acidic sodium rhodizonate and a 5% solution of sodium sulphide. The two chemicals are mixed immediately prior to use and a swab of the combined solution is wiped over the surface to be tested. The chemical changes to a red col colour in response to the presence of lead.
Ray Portable X-Ray fluorescence equipment. This equipment is expensive to purchase and maintain but can deliver an immediate numerical value for lead content without damage to the surface. In due course, the method may become more available.
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Laboratory testing of field samples. An accurate numerical reading of the lead content of an individual sample can be obtained by laboratory analysis. This operation is to be carried out by trained scientific staff in an accredited laboratory such as the Government Chemical Laboratories.
20. 3 Managing Lead & Asbestos Hazards
There are essentially three (3) options open to the contractor who encounters lead based paints and asbestos on the job: 1. 1.Do nothing 2. 2.Stabilisation - Encapsulating or over-coating coating 3. 3.Lead abatement •
Replace painted items
•
Enclosure
•
Removal of lead paint
Do nothing The ‘do nothing’ option is available where the lead based paint does not pose a threat to health. Or the asbestos is already coa coated with a painted surface. To take this option the paint condition is sound, and it is not accessible. If the paint is already over over-coated coated with subsequent layers of paint, it is unlikely that remedial attention is needed. If the paint is in good condition neither chalking nor peeling and cannot be reached, there is no health hazard. In this last case however, there will be a need for regular inspection to monitor the condition of the paint that will ultimately require attention at some time in the future. future Stabilization Lead abatement This procedure is for the manegment of lead based paint hazards only. Reference Material CPC30608 v1.2.docx - Last printed 13/01/2011 1:26:00 PM -
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Abatement involves the ‘suppression, reduction or removal of the hazard from the building’.
20.4 Lead Abatement
Lead abatement may be achieved by: 1 Removal of painted items. 2 Enclosure of paint on surfaces 3 Removal of paint from surfaces Generally, options 1 (Removal) and 2 (Enclosure) are unlikely to be viable for the lead certified painting contractor as they involve other trades. Removal of painted items Where the building elements identified as being coated with lead based paints can be removed and replaced (such as architraves, skirtings, doors, etc), removal may offer a low risk management technique. Enclosure of paint on surfaces It may be possible to seal in the hazardous surfaces with overlying materials (such as plasterboard, weatherboarding, cladding etc). Enclosure should be dust proof and include warning notices of the latent lead hazard for any subsequent renovator. Removal of paint from surface Removal is the commonest technique performed by the painting contractor. It is frequently the solution most popular with the building owner. It does however pose one significant problem for the contractor that is containment and disposal of waste. The risks associated with lead paint removal vary according to the technique employed. The removal of lead paint using LP gas or blow torches will provide lead fumes and toxic gases and is not recommended. Since lead removal produces quantities of waste, it is recommended that the lead content of the soil be tested
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before work is done. Without this test, contractors may not be able to defend themselves against accusations that they have contaminated the soil around the building when they the were working. The test should be repeated on completion.
20.5 Procedures for Lead Paint Removal
Interior Precautions Preparation Remove all furniture from room. Remove soft furnishings, curtains and carpets (where practicable). Cover any furnishings that cannot be removed with plastic and seal. Remove food and medicines. Install plastic drop sheets over floor surface, sealing joins and edges with heavy heavyduty tape. Seal windows, doors, vents, air ducts, etc, with tape to seal room. Seal work area with containment system.
Exterior Precautions Preparations Seal window, doors, vents or any other openings and isolate the work area. Place plastic ground sheet or soil/vegetation and trim
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up 100mm against wall. Do not use ‘dry’ removal method where wind w can spread dust. Collect contaminated water from wet processing.
20.6 Decontamination & Clean up
HEPA filter and vacuum The HEPA filter can remove at least 99.97% of airborne particles 0.3 micrometers (µm) in diameter. Particles of this size are the most difficult to filter and are thus considered the most penetrating particle size. Particles that are larger or smaller are filtered with even higher efficiency. HEPA filters are used in conjunction with an industrial vacuum to extract dust
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HEPA (High Efficiency Particulate air) filter.
20.7 Stabilisation of Lead & Asbestos
The easiest, a and d usually cheapest way to manage lead paint and asbestos hazards is to over paint using, or by covering it with an encapsulant. This is known as stabilization and can provide an interim to long long-term solution to both lead paint and asbestos hazards, allowing more permanent treatment to be deferred until changes in circumstance occur and more information becomes available regarding s safe afe disposal or waste. Materials used to stabilize lead paint surfaces need to be durable and not toxic in themselves. Preparing the surface of lead based paint and previously painted asbestos Stabilization involves applying a covering directly over the existing paint. The effectiveness of this covering relies on adhesion to the existing paint, it is therefore an option only if the existing paint is in sufficiently sound condition to provide the required adhesion and is free of damage. Defects in the pain paint, or in the substrate rate itself, should be rectified prior to applying the covering. When the paint is flaking in places, some removal will need to be carried out to prepare the surface. Usually the existing paint will need to be washed to remove grease gri grime me or dirt. This is best accomplished using trit sodium phosphate. Remove a glossy surface by wet-sanding wet or by using a suitable dc dc-glossing glossing solution. Small areas of flaking and peeling paint will normally ally require rectification rectificati prior to stabilizatio stabilization. Stabi Stabilization lization of unpainted asbestos was covered in section 12.5 of this book.
20.8 Encapsulation
Asbestos
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To seal asbestos insulation effectively, the first coat has to be of low viscosity to aid penetration and consolidate the asbestos- containing surface. Encapsulation of asbestos is a highly specialized task requiring operatives having a full appreciation of the health ramifications. Lead based paint Encapsulation is the process of applying a specialised liquid encapsulant to the lead paint. One such product available for this purpose is “Pre –Prime 167” manufactured by “Atex Coatings”. Of course there are other products available. The difference between over-painting and encapsulation is in the nature of the material used. Encapsulants are specialised materials designed specifically to encapsulate and bond the paint. They are generally more expensive than paints and require particular experience to apply. Encapsulation, which is typically used on external applications, has a longer projected service life than overpainting with normal paints. Even so, lead paint treated by encapsulation requires periodic inspection to ensure that it is continuing to perform. Encapsulation is (like over-painting) dependant upon existing paint adhesion and only substantially in tact paint films are suitable for encapsulation. Encapsulants are not suitable for surfaces subject to wear or friction or substances affected by moisture.
20.9 Information
Further reading on asbestos and lead paint hazards are contained in the appendix of this publication.
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21 Glaze Windows
21.0 Introduction
From time to time as a painter you will be required to replace glass in timber sash windows and some doors prior to repaint. The glazing of windows originally belonged to the painting trade, but on new projects this work is now done by the glazier. However, painters are required on numerous occasions to replace broken or cracked glass as part of the painting contract.
21.1 Safety Handling Glass
Obviously there are a number of hazards associated with handling glass. For example: Cuts to hands Glass slivers flicking into eyes when cutting or nipping glass Injuries to others when glass is not stacked or stored correctly. When glass is being carried, the following points should be observed: It is safer to carry more than one pane at a time as this prevents the sheet whipping Always make sure that the path ahead is clear and free from scaffolding, low doors and other hazards. Never stop suddenly or step backward: anyone following behind may be injured Small panes of glass should be carried under the arm.
21.2 Qualities & Characteristics of Glass
There are a number of different types of glass available. All of these come in different thicknesses Some of these are : Decorated glass – this comes in a variety of textures, patterns, colours and may come with or without frosting. Laminated safety glass - This is made by laying a vinyl membrane between two pieces of annealed glass. The
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resulting sandwich is permanently bonded under heat and pressure, the vinyl interlayer holds the glass together. Toughened glass - Toughened glass is made by heating ordinary “annealed� glass, then cooling it quickly. This makes the product about five times stronger and therefore far harder to break. If it does break under impact, the glass shatters into relatively harmless pieces. These fragments have a very slim chance of cutting or piercing the exposed skin. Wired glass - This is a flat glass with a wire mesh of a square of diamond pattern inserted into the glass during the process of manufacture.
21.3 Glazing Techniques
Measuring Glass Before cutting glass you first need to measure for the size of the glass required. As glass is made from materials that are stable in structure, they do not expand or contract to any degree. Glass however, is usually surrounded by a frame which is either wood or metal. Therefore frames and sashes move according to atmospheric conditions. So it is important when measuring that you allow edge clearance for the glass as illustrated in the AS 1288 Figure 2.39 illustrated below:
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Appendix I - Useful Web Sites www.howstuffworks.com www.paintquality.com.au www.orica.com.au www.wattyl.com.au www.resene.com.au www.dulux.com.au www.paintquality.com www.fauxlikeapro.com www.spscoatings.com www.icipaints.co.uk www.icipaints.co.uk/support/ask/glossary/glossary_a.jsp
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Appendix II - Paint Systems – AS/NZ2311
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Appendix III Paint Types – AS/NZ2311
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Appendix III – Additional Information & Fact Sheets.
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