OPTIMISING RESULTS WITH PREPARATION AND PRE-TREATMENT

The preparation and cleaning of surfaces can be equally as important as the finishing process itself and thorough pre-treatment activity can ensure an optimal result when applying the electroplated layer to the chosen material. It also contributes to the perfect finish when treating aluminium prior to anodising.

Andrew Roper Technical Sales Manager, Alutech Andrew Roper, technical sales manager at metal surface treatment specialists, Alutech, explores the pre-treatment solutions available on today’s market and the benefits of each option. The first, and arguably, the most important stage of any metal surface treatment process is cleaning and failure to carry this out properly risks jeopardising the quality of finish of the end product. Sourcing the correct products for different requirements is essential and putting the effort in at pre-treatment stage will result in a much finer finish and ultimately save time by getting the desired effect at the first attempt. There are now products available which can remove a wide range of mineral oils and polishing compounds to help prepare the substrate for the next stage of treatment.

It is advisable to look for a product which not only offers exceptional performance but has a long shelf life which will provide greater value for money. Also, be aware that the operating temperature will also influence the effectiveness of the cleaning products and how well they perform with the potential for damage increasing if temperatures are higher than those recommended.

Generally, pre-treatment cleaning chemicals can be classed as either those designed for electro cleaning or for more heavy-duty soak cleaning. In addition, pre-treatment cleaners which contain specialist surfactants are usually the best choice where degreasing is required and the solution should also contain inhibitors, this will help prevent damage to the substrate during the soak process.

Soak cleaners

Where soak cleaners are used, it is the chemistry of the bath which is active in removing grease and other unwanted dirt from the surface of the object to be treated.

Try to source a long-life soak cleaner specifically formulated for the job, for example, specifically for cleaning aluminium and its alloys. You should look for a product which removes oils and polishing compounds without interfering with, or causing damage to, the substrate. In the case of aluminium a cleaner with a pH as close to neutral as possible would be best.

Alternatively, you may need a more heavyduty soak cleaner which will not etch surfaces but is still suitable for most materials, including aluminium. It should also be ideal for degreasing and removing polishing compounds. Be sure that your chosen product is also effective across a range of temperatures and concentrations which may be affected by the level of soiling that needs removing.

Electro cleaning

Alternatively, electrocleaners will work slightly differently by running a current either anodically or cathodically through the soak bath. Ferrous materials will be treated anodically and non-ferrous will be cathodically. This is helpful where there is more dirt and grease to be removed and where the process is required to be accelerated. The most effective products where heavy-duty treatment is required for worse soiling will be a pre-treatment cleaner which has excellent degreasing properties and a long shelf life. The product should be capable of removing high levels of grease and oil. These are ideal cleaners for use prior to galvanising for heavily soiled substrates. Be aware that electrocleaners are not suitable for use with aluminium.

Alkaline

The majority of pre-treatment cleaners are alkaline which tend to be most effective and versatile. Acidic ones are available but alkaline cleaners tend to be the best option for surface grease removal. The differing levels of alkalinity and types of chemicals used in creating the appropriate pH level in the solution will dictate which types of substrate it is best suited to.

Although non-caustic alkaline cleaners can be used on most substrates it is advisable to use highly caustic pre-treatment cleaners where possible for optimum results but with greater caution and never on aluminium.

At Alutech we have developed a range of pre-treatment cleaners for the full range of metal finishing processes. Our UltraClean products are formulated for electro cleaning or heavy-duty soak cleaning and are ideal as pre-treatments for various processes at a range of specified operating temperatures and different levels of substrate soiling.

For more information visit https://alutech-ast.co.uk/.

Unsoaked Aluminium

Before Soak Cleaning