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Finishes: Aluminium Coating.

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The aluminium powder coating consists in the electrostatic application of powder paint on the surface of the aluminium. The paints used for this finish are polyester resins or polyurethane. We must mention the excellent resistance of these finishes to UV rays, weathering and corrosion.

One of its main advantages is that there is a wide range of colours. All these possibilities of colouring and shading are reflected in the RAL chart, which is a standard that gives to each colour a 4 digits code.

Two types of plants can be used for the process; horizontal or vertical. The system used by Extrual is the vertical coating paint, where the profiles are hung from hooks, remaining in this position.

In Extrual we supply our customer with an unlimited range of colours, in order to meet the aesthetic demands of any industrial field. This type of surface treatment add to the coating an aesthetic finish that imitate wood grains. Each variety is made up of a colour base and a decorative film.

In what consists the process of aluminium powder coating?

1. Cleaning of the surface.

 An acid water solution is sprayed to leave the surface clean of greases, dust or any other rest of dirt that can remain after the extrusion process.

2. Attack of the surface.

Through this process the natural aluminium oxide layer is eliminated. This process can be carried out in an acidic or in an alkaline medium.

3. Transformation of the anchor-base layer (primer).

This is one of the most important steps in the process. The profiles are covered with a solution that provides adherence. Afterwards the profiles are taken to a drying oven to prepare them for the next step.

4. Application of the powder paint.

This is the treatment that determines the process of powder coating. A number of electrostatic guns with positive charge spray the powder paint on the profiles with negative charge. By this, the paint is adhered to the surface.

5. Polymerization in oven.

In this step we carry out the thermal-curing of the resins. They are put at a temperature between 180º and 200ºC for about 20 minutes in air convention ovens, which melt the resins that are finally adhered to the profile. The resultant thicknesses are very uniform, from 60 to 80 microns.

Afterwards we would carry out the tests required by the certification body for the quality seals; QUALICOAT (SEASIDE), QUALIDECO.

For the maintenance of coated aluminium doors and windows, is advisable to use neutral products and non-abrasive elements. In such way, the protection will last for many years.


Useful links

RAL Chart (here)

Video AEA (here),


Other related articles

Aluminium Finishes: Anodizing. (here)

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