A correct pretreatment of aluminum is mostly important for a good resistance and a good adhesion of the powder coat layer.

For this reason, the DecoralLab has carried out a study to determine and evaluate its role, showing the defects that can be observed where no pretreatment (or uncorrect pretreatment) has been made.

The following aluminum samples have been prepared:

- No pretreatment;

- Chrome pretreatment;

- Chrome-free pretreatment.

Each kind of pretreatment then has been tested for what regards:

- Resistance to corrosion – salt-spray; (Picture 1)

- Adhesion of the powder-coat layer  - cross-cut test, followed by impact test. (Picture 2)

Picture 1: corrosion test.

Left to right: non-pretreated sample; chrome pretreated sample; chrome-free pretreated sample

Picture 2: adhesion test.

Left to right: non-pretreated sample; chrome pretreated sample; chrome-free pretreated sample

The results have proved how pretreated aluminum surfaces perfectly pass the tests carried out, while non-pretreated ones show serious signs of corrosion and loss of adhesion of the powder coat layer in both the tests made.