Standard anodizing, also known as Type II anodizing, is the standard specification used throughout the world for commercially anodized aluminum. Automotive, aerospace, medical, military/defense, and many other industries specify standard anodizing for their parts and components.
Type II anodizing utilizes a sulfuric acid solution to boost the natural oxidation of aluminum alloys. The resulting oxide coating offers improved wear resistance, corrosion resistance, and hardness over aluminum’s naturally occurring oxide layer. Standard anodized coatings can be applied to all aluminum alloys.
Benefits of Standard Anodizing
Standard anodizing provides a number of benefits. Sealed, Type II anodized parts are heat resistant up to the melting point of aluminum (1221°F/660°C). Standard anodized coatings provide excellent electrical insulation and are highly resistant to corrosion from salt water, high humidity, and other environmental factors. Type II coatings are proven to withstand a minimum of 336 hours of 5% salt spray testing, per ASTM B 117. The Rockwell surface hardness rating of Type II anodized aluminum can be as high as 55, while the maximum rating for unanodized aluminum is only 44.
Dyeing & Finishing
Type II anodized coatings are also stain resistant and can be dyed or colored in a wide range of colors; they also provide improved paint adhesion. Standard anodic coatings can also be bright dipped to produce a brighter, more reflective appearance than raw aluminum.
By modifying the composition of the chemical bath, finishes from matte to high gloss are possible on standard anodized coatings. With the right finish, machining lines, extrusion lines, and scratches can be blended in and made all but invisible.
Industry Standards
Applicable standards for Type II anodizing include MIL-A-8625 Types II and IIB, AMS 2471 for undyed anodized coatings, AMS 2472 for dyed coatings, BS EN ISO 12373/1 for decorative coatings, and BS EN 3987 for architectural coatings.