Anodising is an electrochemical process that is used to thicken the protective oxide layer on a metal. As well as increasing the protection provided, anodising can also be used as a way of colouring these metals with a layer of hard, permanent colour.

Titanium is used as the anode of an electrochemical circuit. Oxygen from the acidic electrolyte is produced at the anode and this can react with the metal to thicken the metal oxide layer. The higher the voltage, the thicker the oxide layer can become.

The colour produced by anodising titanium is an example of ‘structural’ colour: rather than the simple production of pigment. The colour comes from light scattering through the oxide layer.

Anodising Titanium – Pupil

Anodising Titanium – Teacher/Technician

Anodising Titanium – Risk Assessment

Photo by Mauro Cateb under a Creative Commons Attribution-Share Alike 3.0 Unported license