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Important Pre-treatment Tips for Powder Coating Aluminium

February 14, 2020

Powder coating is one of the few options in coating products made out of metal. You see, powder coating is the electrostatic application of fine ground dry paint film to the surface of a metal like aluminium and others. 

Products that undergo powder coating must be pre-treated first. Pre-treatment, also known as chemical processing, is a process that helps the material surface to become clear and free from oil and grease. It provides a good hold of the film and forms a surface layer that prevents corrosion. If you are powder coating aluminium materials, then chemical pre-treatment is the best option.

The pre-treatment process follows a series of important steps. So, here are some tips you must follow to make the pre-treatment process successful.


Degreasing is the first step for the pre-treatment process. The type of de-greasing method that one should use would depend on the surface of the material and the number of pollutants. Some of the types of de-greasing are solvent cleaning, vapour degreasing, emulsion cleaning, and alkali cleaning. 

If you want to fully preserve your surface, the solvent cleaning is the best option for you. This type of cleaning uses Alkene solvents with clean cloth to easily wipe off heavy greases or oils from the surface. Another de-greasing method that utilises the use of cloth is vapour degreasing. It uses purpose-made solvents that can remove oils and minerals.

A de-greasing method that uses solvents with a higher pH level is called emulsion cleaning. With emulsion cleaning, the materials are dipped into the solvents for a couple of minutes. The dipping action of materials is also applicable to alkali cleaning. However, if your materials are made out of aluminium, then stay away with alkali cleaning.


One known weakness of metals is corrosion. When an object is exposed to a damp environment, there is a chance that this object will rust over time. Fortunately, acid cleaning can solve the corrosion problem since rust is easily dissolved by acids.


The activation process provides active crystal spots when conducting phosphate coating. To date, there are two options for the activation process. The first one is acidic activation. Acidic activation can be ready in hard water, which yields bigger crystals in the coating. Aluminium materials don’t react well with this method, so avoid this type of activation.

The best activation method for aluminium materials is basic activation. Basic activation provides a finer and more resistant finish. 

Conversion Coating

Phosphating is considered to be the best conversion coating method. It is a process wherein phosphates are bonded to the surface, making the material surface reactive to paint.

There are two types of phosphating. Zinc phosphating uses a bath that contains saturated phosphoric acid with zinc phosphate. The acid of this solution targets the iron particles of the surface, which form phosphate layer due to their chemical reaction. Iron phosphating, on the other hand, involves the use of sodium or dihydrogen phosphate in combination with catalysts. 

With these pre-treatment processes, it is important that you know which method would be good for your aluminium materials. If you have more questions about pre-treatment and powder coating, you can contact us now at G.P. Industries.

GP Industries Pty Ltd

Head Office

1 Regal Court,
Vermont South VIC 3133

Phone: (03) 9802 1355

Fax: (03) 9802 6027

Email: gp_ind@bigpond.com


Factory G,
20 Burgess Road,
Bayswater North VIC 3153

Phone: (03) 9761 7676

Fax: (03) 9761 7671

Email: gpfactory@bigpond.com

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