Anodising is an electrochemical process used to produce durable and decorative finishes on components made of aluminium or aluminium-based alloys.
Aluminium, in an untreated form produces a protective oxide coating on exposure to the atmosphere. This oxide is inherently protective, but being very thin provides little resistance to long term corrosion. The coating can, however, be thickened by anodising.
Sulphuric acid anodising which is extensively used for general industrial and architectural applications, produces a coating (typically silver or pale grey) which can be left natural or dyed to produce a wide range of colours.
(various other colours can also be matched providing sample colours are provided)
The Anodising Process.
The principle of anodising developed out of aluminium’s ability to form this oxide layer which can be electrochemically produced under controlled conditions to provide thick protective coatings. In essence the process consists of passing an electric current through an acid solution in which the immersed aluminium component acts as the anode, and aluminium or lead typically provides the cathode.