The most common anodising processes, for example sulphuric acid on aluminium, produce a porous surface which can accept dyes easily. The number of dye colours is almost endless, however the colours produced tend to vary according to the base alloy. Though some may prefer lighter colours, in practice they may be difficult to produce on certain alloys such as high-silicon casting grades and 2000-series copper alloys. Another concern is light-fastness of organic dyestuff, some colours ( reds & blues ) are particularly prone to fading. Black dyes and gold produced by inorganic means are more light fast. Dyed anodising is usually sealed to reduce or eliminate bleed out.
Dye colours range from champagne to black & bronze, blue, purple, red, pink, green, orange, gold, silver & grey.