Class I and Class II anodic coatings are designations created by the Aluminum Association for the purpose of codifying the specification of anodized aluminum.
Class I coating has a mil thickness of 0.7 (18 microns) or greater
Class II coating has a minimum mil thickness of 0.4 (10 microns)
Class I coating is a high performance anodic finish used primarily for exterior building products and other products that must withstand continuous outdoor exposure.
Class II coating is a commercial anodic finish recommended for interior applications or light exterior applications receiving regularly scheduled cleaning and maintenance such as storefronts.
Class I and Class II coatings should not be confused with Type I, Type II, and Type III anodic coatings as described in the authoritative anodizing standard, MIL-A-8625. Type I anodize refers to chromic acid anodizing. Type II is normal “clear” sulfuric acid anodizing. Type III is “hardcoat” using sulfuric acid or mixed chemistry electrolytes.
All Linetec anodize finishes are produced as a Class I coating, with the exception of ANO-204 Clear, which is a Class II coating. Clear anodize is available in both Class I and Class II.
Class II anodic coatings are recommended for interior applications or light exterior applications receiving regularly scheduled cleaning and maintenance such as storefronts and entrance ways. Class II anodize is not as durable or wear resistant as a Class I finish.
Class I anodic coating is a high-performance finish used for exterior building structures and other products that must withstand continuous outdoor exposure. Class I anodize is more resistant to salt spray and the sea coast, and it is more durable in high traffic areas.