Chromic Acid Anodizing Example

Type I Anodizing: Chromic Acid

Type I Chromic Acid Anodizing is an electrochemical process that creates a thin aluminum oxide film by rapidly controlling the oxidation of an aluminum surface. The resulting aluminum oxide film is electrically non-conductive. The active ingredient in Type I Anodizing is chromic acid. Type I anodizing produces a thinner film than Type II and Type III Anodizing (hard coat) and produces enhanced drawing and forming characteristics. Chromic acid anodizing is used for flight-critical aluminum components that are subjected to high stresses, such as landing gear. Type I Chromic Acid Anodizing works best on aluminum with few alloying elements.

Chem Processing Inc. Type I Anodizing Capabilities:

  • Typical Formed Thickness is 0.00005 to 0.0002 in.
  • Available Masking for Selective Surface Anodizing
  • Salt Spray Corrosion Test (minimum 336 hours of salt spray resistance)
  • Thickness Analysis

Applicable Specifications:

  • MIL-A-8625F Type I
  • MIL-STD-186 D (201)
  • ASTM B580-79 (Type G)
  • AMS B117
  • MIL-STD-171D (7.1.1 & 7.1.2)
  • MIL-F-14072B (E511)
  • AMS2470
  • CP 14.06 (UTC Aerospace Systems/Hamilton Sundstrand)

Properties of Type I Anodizing:

  • Corrosion Resistance: The aluminum oxide film is resistant to atmospheric and saltwater
  • environments.
  • Electrical Insulation: Aluminum oxide film is dielectric.
  • Paint Adhesion: Aluminum oxide film is a chemically active surface for painting.
  • Adhesive Bonding: Aluminum oxide film improves adhesion and bond strength.


Chem Processing Inc. offers chromic acid anodizing services to Illinois, Wisconsin, Iowa, the Midwest and beyond. CPI is strategically located by highway routes to Chicago, Milwaukee, Madison, St. Louis, and Minneapolis. The CPI facility is minutes from Rockford Chicago International Airport, a major Midwestern air freight hub, enabling efficient door-to-door delivery across the United States or across the globe.