Not all anodizing is the same.
“Hardcoat Anodize” is very specific type of anodize that gives aluminum parts greater abrasion and corrosion resistance than that provided by the more conventional plain anodize processes. It is sometimes referred to as “Alumilite Hard Coat,” “Martin Hard Coating,” “Hard Anodizing” or “Hard Coating”. The coating is a hard aluminum oxide that is formed by the electrochemical reaction of aluminum with oxygen. It is chemically bonded to the aluminum. Hard Anodic Coatings are defined by Military Specification MIL-A- 8625, Type III, Class 1. In order to meet this specification, the coating thickness must be held to .002″ +/- 20%, pass the abrasion resistance requirement found in the specification, and be routinely tested to these parameters to insure quality. Plain, or conventional anodize has no such requirement for thickness or wear resistance. Other coatings, for instance paint or powder, likewise have no such requirement for abrasion resistance. The threaded and non-threaded couplings and adapters used in firefighting greatly benefit from the abrasion and corrosion resistance provided by Hardcoat Anodize. It is the specification Red Head Brass follows in manufacturing its quality aluminum products.
The quality of Red Head’s Hardcoat Anodized couplings is evidenced by the results of the NFPA required 120 hour Salt Spray Corrosion Resistance test of Red Head’s (on left) and competitor’s couplings as shown in the photo.