VA colouring

Before stainless steel materials are coloured, they must be free of grease and clean. With some surfaces, we recommend to activate them by special pickling agents based on hydrochloric acid.

The colouring process is done by immersion and is generally comparable with the black oxidation process. The biggest differences consist in a particular working sequence, the temperature of the reaction bath, and special chemical products made by Brünofix. However, the type of the surface is completely different.

Whereas the surface is oxidised during black oxidation in a bath with a strong alkali (magnetite), i.e. conversion, VA blackening creates an oxidic-sulphidic coating. VA colouring also means that post-treatment with a corrosion protection product – essential for black oxidation – is not required.