Hard Anodizing

Hard Anodizing, often called “Type III Anodizing” as denoted by the MIL-A-8625 specification, is an electro-chemical process that creates a controlled oxide film on the surface of aluminum. Hard Anodizing utilizes sulfuric acid, low bath temperatures, and constant current rectification to achieve a very hard coating (60-70 Rockwell C).


Hard Anodizing is generally used for applications that need a corrosion, abrasion, and wear resistant coating. The appearance of the coating ranges from light to dark gray, depending on the alloy makeup of the aluminum base material, and it can also be dyed black. Parts can be processed with multiple finishes, such as Hard Anodize/Chem Film or Hard Anodize/Electroless Nickel Plating.


  • Compatible with adhesives
  • Excellent lubricity (Particularly with a Teflon Seal)
  • Highly resistant to marine and atmospheric corrosion
  • High operating temperatures
  • Electrically resistant
  • Galvanic neutrality (prevents galvanic corrosion from interaction between dissimilar metals)

Download our free PDF on Engineering Considerations For Anodizing Aluminum


  • Thickness ranges: 0.0001″ to 0.0030″  NOTE: anodizing thickness constitutes 50% build, 50% penetration into the substrate, which must be accounted for when calculating pre-anodize machining tolerances
  • Available with PTFE (Teflon®) impregnation for enhanced lubricity)
  • Rack and bulk processing
  • Precision masking for selective anodizing
  • In-house salt spray testing ber ASTM B 117
  • In-house coating weight analysis
  • Taber abrasion testing
  • Post anodize seals available for increased corrosion resistance but may reduce surface hardness
  • Type I and Type II as masking


  • MIL-A-8625F Type III
  • ASTM B580-79 (Type A)
  • MIL-STD-171
  • AMS 2468 & 2469


  • Aerospace/Aviation: wear resistance, dry lubrication, longevity and electrical insulation
  • Firearms: corrosion and wear resistance
  • Machinery: abrasion resistance for high-speed machine parts
  • Electronics: uniform emissivity and a high dielectric
  • Marine/Naval: corrosion resistance in salt-water environments
  • Oil and Petrochemical: corrosion protection and wear resistance.
  • Ordnance: corrosion protection, abrasion resistance and wear resistance
  • Cookware: corrosion protection and non-stick properties
  • Molds and Dies: improved release properties and abrasion resistance
  • Sporting Goods: improved durability and performance