THE JOURNEY: CORK This is a book documenting the material - cork and its production in Portugal. by Steven Li- Wei Hsiao
Most of the photos in this book are taken on site at Portugal. If not, it is labelled.
THE JOURNEY
Day 1 Montado cork forest Cork stopper Insulation cork
Amorim Equipar Amorim Isolamentos
Day 2 Cork flooring Cork Composites
Amorim Revestimentos Amorim Cork Composites
Day 3 Wall covering and granulated cork
Granorte
PREFACE Cork is the material that covers the trunk and branches of the cork oak, a tree related to the oak, which is the only tree capable of naturally regenerating its bark after it is removed. Cork is harvested by experienced professionals at intervals of nine years, which cause no damage to the tree. It is not necessary to axe the cork oak to obtain cork.
Many cork oaks growing together create what is known as the “Montado” cork forests, a name given to them in the 14th century that refers to the biodiversity found in this environment, since the term “Montado” in Portuguese refers to animals that can be “mounted”. The Montado is essentially distributed among southern Mediterranean and North African countries; yet it is Portugal that holds the greatest concentration with over 30% of the world’s total. The Montado is home to an endless variety of animal and plant species and has greatly contributed to maintaining a regular ecosystem while protecting the soil and preventing desertification. It is also important to note that the Montado helps capture carbon dioxide, the gas responsible for global warming, by holding up to 14 million tons of CO2 per year.
The cork tree only grows on slightly acid soft soil that allow water pass through soil quickly. The bushes grow around cork tree are composed by several different species of plants: “Sargaços” (Cistus sp.) “Tojo” (Ulex sp.) “Rosmaninho” (Lavandula sp.) “Alecrim” (Rosmarinus officinalis) “Urze” (Erica sp)
NATURE The Montado ecosystem
There are two main pine tree in the Montado forest: Umbrella pine (Pinus pinea) Maritime pine (Pinus pinaster) used for timber.
Umbrella pine cone - farmers take the edible pine seed for food or feed livestock such as horse, pig, goat and sheep.
Excessive cork tree branches will be cut and gather into one place. When the oak tree is at the end of its life span - around 200 years. Farmers do need to ask for government premission to cut it down. All of these will be used for fireplaces or destroy locally to prevent fungus grow or contaminate the Montado.
Cork tree before harvesting - Copyright by APCOR
CORK HARVESTING The life cycle of cork starts with the extraction of the bark from cork oaks, the so-called harvesting or stripping which is carried out during the most active stage in the annual growth of the cork, from mid-May or early June to the end of August. Unfortunately during my visit, the weather was not warm enough to start harvest. Many people may not know that it takes 25 years for cork tree to start produce cork and be profitable. Each tree has to reach a circumference of 70 cm when measured at 1.5 metres from the ground. From then on, the cork can be harvested from the tree for on average 150 years. The first stripping, which is known as “desbóia”, produces cork of a very irregular structure which is too hard to be easily handled. This is the socalled virgin cork which will be used for applications other than cork stoppers (flooring, insulation etc.), since its quality is far from that necessary to manufacture stoppers. 9 years later, the second harvest produces material with a regular structure, less hard, but still not suitable for cork stoppers - this is known as secondary cork. It is from the third and subsequent harvests that the cork with the best properties is obtained, suitable for the production of quality corks, since its structure is regular with a smooth outside and inside. This is the so-called “amadia” or reproduction cork. From then on, the cork oak will supply good quality cork every nine years for around a century and a half, producing, on average, 15 to 16 bark strippings throughout its life.
“Machada” - axe used for harvest cork bark.
The stripping of the cork tree only can be done by specialists, since much manual skill and experience is required in order not to harm the tree. The stripping process consists of four steps:
Separating process - Copyright by APCOR Opening - A vertical cut is made in the cork, choosing the deepest crack in the cork bark. At the same time, the edge of the axe is twisted so as to separate the outer from the inner bark.
Separating - The plank is then prised off the tree, by inserting the edge of the axe between the strip and the inner bark. The axe is twisted between the trunk and the cork strip to be extracted.
Dividing - A horizontal cut defines the size of the cork plank to be removed and what is remain on the tree.
Extracting - The plank is removed from the tree with care so that it does not split. The larger the planks extracted, the greater their commercial value. The removal of entire planks depends on the skill of the workers. After the first plank has been stripped, the operation is repeated over the whole tree.
Cork extraction - Copyright by APCOR
Finally, the tree is marked, using the last number of the year in which the extraction took place. The dark brown colour indicate the cork is newly harvested at year 2010. Grey colour indicate the cork was harvested at year 2001.
NURTURE Since cork oak is the only tree capable of naturally regenerating its bark after it is removed. It is very important that the oaks are well looked after and during harvesting. Here are some examples:
Cork bark
Tree tissue
Excessive bushes could interfere cork tree’s growth. Workers will go around forest cutting excessive bushes, but left on site to fertilize the soil and nurture cork tree.
By accidentally removing tree tissue, the oak will need several year to cure in order to reproduce bark again. Once again, it is important that harvesting is done by professionals.
Cobrilha (Coroebus undatus), a worm that lives and feed on cork oak. It creates tunnels inside the cork bark. It is harmful to the tree in some ways, but more a commercial problem.
CORK PRODUCTION SUMMARY Best quality cork
Bottle stopper
Worst quality cork
Flooring & wall covering
At each production stage, any cork dust are used as biomess for powering electricity. Off-cut and waste are to be reused, if not to the next application. i.e. Waste generated from bottle stopper will be use for flooring and wall covering. Waste from flooring and wall covering will be usef for Insulation cork and so on.
Insulation cork
Cork Composit
NATURAL CORK STOPPER Cork has always been associated with champagne and fine wine. It has been used as a seal for centuries, whilst it can be easily squeezed into a bottle; its physical property allows it to spring back into its original form, immediately creating a prefect impermeable barrier and stopper for fluid.
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1. After the harvest, the cork planks are stacked in piles. There they remain exposed to sun, wind and rain. As to allow the cork to stabilise, this stabilization period usually take six months. 2. Boiling is the process of immersion of cork planks in clean boiling water. The objectives of the boiling are to clean the cork, extract water-soluble substances, improve flexibility and elasticity.
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3. After another two to three weeks of stabilization, it is cutted to more rectangular size for further production use. 4. The cork planks are cut into strips slightly wider than the length of the cork stoppers to be produced. 5. Punching is the process of perforating the strips of cork with a drill.
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6. Stopper going to be cut to specified final dimension and to be polish. 7. Washing, disinfection and dye if needed. 8. Printing or branding the type of marking to customers’ specifications. This method used are ink printing or traditional heat branding. This photo is using an ink printing. 9. Corner of the factory floor.
TECHNICAL CORK STOPPER Technical corks were created for bottled wines which are consumed within a period of two to three years. They consist of a very dense agglomerate cork body with natural cork disks glued on one or both ends.
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1. Agglomerated cork. 2. Agglomerated cork are sorted in various size 3. Food grade glue are applied onto agglomerated cork. 4. Agglomerated cork are squeezed into cylinder shape than cutted. 5. Sample of cutted agglomerated cork stopper.
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6. Natural cork disks glued onto one or both ends then shaped into customers’ specified dimension. 7. Sample of technical cork stopper in process. 8. Laser controlled quality control machine scan for defect. Unqualify stopper will be re-grind and re-use.
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9. Washing and disinfection the cork stoppers. Also dye to any colour to customers’ specification. 10. Sorting cork stopper for marking and branding. 11. Traditional heat branding.
CORK FLOORING & WALL COVERING Cork flooring and wall covering were created because its unique properties do not absorb dust and are resistant to bacteria and fungus. Good sound and thermal insulator also makes cork an ideal material for flooring.
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1. Two times heat pressured press. 2. Instant fan cool down to room temperature. 3. Cut agglomerated cork sheet into specified dimension. 4. Glue applied onto cork sheet
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5. Apply surface texture. Original cork flooring requied traditional varnish or lacquer finish. Depending on customers’ specification, a vinyl layer can be applied for non-cork texture such as stone and wood. 6. Bevel flooring joint.
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7. Stone cork flooring sample. 8. Traditional cork flooring sample. 9. Wood cork flooring sample.
INSULATION CORK
Portuguese Pavilion, Expo 2000 Hannover
Insulation cork are widely used in the contruction of buildings, wine cellars and refrigeration industry because it achieve a higher degree of thermal, acoustic and anti-vibration insulation compare to normal cork.
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1. Insulation cork are made from “left overs“ cork from stoppers, flooring and wall covering. 2. Grind into 9 - 14mm agglomerated cork. 3. Superheat steam to 400 degree celsius.
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4. Put agglomerated cork into a seal chamber and steam it. Under 400 degree heat, cork will expand up to 30%. It will release its natural adhesive within to keep it as a piece. 5. Seal chamber released. 6. The insulation cork block will move to cooling chamber where these pins will penetrate the block then cool insulation block with hot water. 7. Insulation cork will left to dry until it reach room temperature. 8. Stool made for Serpentine Gallery Pavilion 2012, London.
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9. Show piece at factory.
CORK COMPOSITES Most of us would recognise cork as this form - agglomerated cork. But there is much more than we think there is.
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1. Any unwanted waste cork from other industry are transported to this factory. Workers sort cork by grade and types. 2. Cork are grinded, glued and compressed.
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3. With different pressure used in compression process. Agglomerated cork block or cylinder are made into more than 500 different type of properties that suited to the requirements of industries such as aerospace, aeronautics, the composites and the automotive industry. 4. Example of agglomerated cork cylinder. 5. Here is an example that agglomerated cork cylinder are trimmed into agglomerated cork sheet. 6. Then made into cork pin board.
NOTHING IS WASTED Cork is further classified as an eco-efficient material with a life cycle where waste from all of its manufacturing process is reused as biomass to produce new products. During the cork production process no waste is released into the environment. Even the cork powder produced from the system is used as biomass in producing steam or electric energy.
Vaccum test
Compression test
SEM micrograph of natural cork (after boiling)
UNIQUE PROPERTIES Very light Impermeable to liquids and gases Elastic and compressible An excellent thermal and acoustic insulator Fire retardant Highly abrasion resistant But it is, above all, cork is 100% natural, recyclable and reuseable.
Special thanks to everyone helped me on this journey of cork: Martin Harding Claudia Pimenta Conceicap Santos Silva Miguel de Sousa Jose Augusto Lopes Infante Ramiro Tavares Eduardo Sousa