Hardcoat anodising is a variation of anodic oxidation. Particulary hard and abrasion-proof oxide layers are generated on aluminium alloys thus allowing that these materials can be used for special applications. These layers are made in a cooled electrolyte by using direct current through the conversion of aluminium into aluminium oxide.
The pores of those layers are more compact and smaller in diameter compares to common anodised layers. Hardcoat anodised layers show a self coloring from grey to brown which is due to the alloy. Mainly thicknesses ranging between 30 - 60 microns are used and the outgrowth is only about 50%.