How is hard coat anodizing different from other types of anodizing?

Aluminum anodizing is generally divided into three types. Type I is chromate anodized (or chrome substitute) and is very thin, approximately 0.0001 inch thick. Type II is traditional sulfuric acid anodizing and can be decoratively dyed in almost any color in thicknesses from 0.0002 – 0.0006”. Hard coat anodizing is Type III and is done under more stringent process conditions to produce harder, denser, thicker and more wear-resistant coatings. Hardcoat thicknesses can range from 0.0005 to 0.0030” and beyond but depend on the specific alloy being anodized.