Chromic Acid Anodize
Mil-A-8625F Ty1

TYPE I "Chromic Acid Anodize"
Color will vary from clear to dark gray depending on alloy. Copper bearing alloys only yield gray colors. Not as readily dyed as sulfuric anodize due to thinness of coating.
New salt spray requirement is 336 hours (5% solution per method 811 or FED-STD-No. 151).
Type I
Chromic acid anodized coating. This process is used principally for the treatment of aircraft parts. An example is the Bengough-Stewart process where a 30 - 50 g/l chromic acid bath is maintained at 100° F and the voltage is gradually raised to 50V. Adjustments are made for high copper, zinc, and silicon alloys. Coating weights must be greater than 200 mg/ft2. Criteria for corrosion resistance, paint adhesion, and paint adhesion testing must be specified.
Type IB
Low voltage (22)2V) chromic acid anodized coating. Typically associated with higher temperature, more concentrated chromic acid electrolytes. Coating weights must be greater than 200 mg/ft2. Criteria for corrosion resistance, paint adhesion, and paint adhesion testing must be specified.
Type IC
Anodized coating produced in a non-chromic acid electrolyte. As with other Type I coating processes, the treatment is designed to impart corrosion resistance, paint adhesion, and/or fatigue resistance to an aluminum part. Coating weights must fall between 200 - 700 mg/ft2. Criteria for corrosion resistance, paint adhesion, and paint adhesion testing must be specified.current is applied. The tank lining is commonly the cathode.