MIL-A-8625F1
RoHS Compliant
Teflon Impregnation Available
Compatible with Aluminum Only
| Class 1 | Clear Hardcoat | Thickness .002 |
| Class 2 | Black Hardcoat | Thickness .002 |
Type III anodizing or “Hardcoat” anodize is typically applied when the anodize film needs to be thicker and more wear resistant than regular anodize, this can be appropriate for heavy wear industrial parts intended for use in aggressive or highly corrosive applications. The total thickness of the coating is .002″ (generally the hardcoat thickness is .001″ penetration and .001″ build up). To achieve this, the sulfuric/water solution (approx. 180-200 grams per liter) must be chilled and maintained at 32-35 degrees Fahrenheit and much higher DC voltage is needed. The higher voltage is necessary to overcome the highly electrically resistant coating as it builds. Given the higher energy requirements and longer cycles, hardcoat is more expensive than regular Type II anodize.
The nature of the hardcoat process darkens the aluminum which can range from greens to dark grey. Because of this, the finish is usually specified as “clear” or “black”. Other colors do not provide satisfactory results in most cases.
In place of nickel acetate seals, often Teflon is specified as a final coating after anodize (and dye if called out). This helps seal the part and adds further lubricity to an already wear-resistant coating.