Anodizing type
Chromic Acid Anodize - Type I
Type I or chromic acid anodizing is used primarily by our aerospace customers in precision applications, as it is the thinnest form of anodizing and does not appreciably change a part’s dimensions. Chromic acid anodizing can be used for inspection of aluminum forgings or castings by noting evidence of chromic acid bleed out from laps, cracks, seams, etc. The resulting color from chromic acid anodizing will vary from light gray to dark gray depending on the alloy. Type 1 is not as readily dyed as sulfuric anodize.
Sulfuric Acid Anodize - Type II
Type II aluminum anodizing is performed using a sulfuric acid bath to create the anodic aluminum oxide surface. This method is often referred to as “conventional anodizing” for good reason. Type II anodizing is very versatile and provides an ideal surface for dye application. The resulting color will vary with alloy composition. Aluminum with low alloying elements will show practically no color change. This means Type II can be dyed practically any color or shade.
Sulfuric Acid Anodize - Type III
Type III sulfuric acid anodizing is commonly referred to as “hardcoat anodizing” as it is used to protect aluminum parts in harsh wear applications. Hardcoat anodizing creates a denser anodized layer that may reach up to 0.002″ in thickness. Type III is dyed easiest of all because of the deep pores created. The hardcoat process darkens and alters the base metal enough so that the color is dramatically different than Type II.
