Anodisation is a process in which electricity is used to deposit a thin layer of oxide on the surface of a metal from a solution of a metal salt. Most metals can be anodised. These include iron, titanium, and aluminium. The resulting oxide film on the surface is usually very thin - typically a few hundred nanometres. Because of this it is able to selectively reflect particular wavelengths of light, and this results in the metals having bright and iridescent surface colours. This phenomenon is the same as that which causes the colours of the rainbow in petrol or oil that lies on water.

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Copper is a difficult metal to anodise, so much so that there is no large-scale commercial anodisation, as there is for other metals. This is because the conditions needed to achieve anodic deposition are 'challenging', involving the use of caustic solutions at high temperatures.

 

At element29 we have used our expertise to develop a work-around to the conditions. This enables us to achieve vivid and iridescent colours over large areas (multiple square metres) at affordable costs. Our technology is a world-first in the production of aesthetic oxide films on copper and its alloys.