THE USE OF THE DYE CI ACID BLUE-45 IN THE ELECTROLYTIC COLORING OF ANODIZED ALUMINUM

The electrolytic colouring of anodised aluminium from acidic tin(II) s ulphate solutions in the presence of the dye Alizarin Saphirol B (Cl A cid Blue 45) has been investigated. The method combines electrolytic c olouring and adsorptive dyeing in a single stage and expands the range of colours which can be produced by the electrolytic colouring proces s. A dye concentration in the acidic tin(II) sulphate colouring bath o f 7.5 g/l and a treatment time of 1-2 min, at 15 V (50 Hz), results in a grey-blue hue with high fastness properties and resistance to corro sion. The mechanism of the action of the dye is discussed.