1) What is anodizing and how is it performed? Anodizing is an electrochemical means of building an aluminum oxide film on the surface of aluminum. The process consists of making the aluminum part electrically positive, or the anode, in a suitable electrolyte. The most frequently employed electrolyte is sulfuric acid. In a sulfuric acid bath through hydrolysis, oxygen is released in an accelerated and uniform manner which reacts with aluminum to form an oxide film. Much less frequently, other electrolytes such as chromic acid is used when dictated by specific requirements.
2) What does anodizing accomplish? Anodizing changes the physical and chemical characteristics of the aluminum. The anodic film which is formed on the surface: a) renders the surface harder and more abrasion resistant b) insulates the aluminum surface against passage of electricity c) helps improve upon the natural corrosion resistance of aluminum and d) allows aluminum parts to be decoratively colored by absorbing dye into the anodic film.
3) What is etching? Etching is a chemical process which cleans and prepares the surface of aluminum for further processing by uniformly removing metal to hide minor surface scratches, remove surface oxide, and impart a clean satin appearance. Thus depending on the concentration and temperature of the etchant solution and the length of time parts left in the solution, one can remove anywhere from a negligible amount to over a hundredth of an inch.
4) What is chemical conversion coating or iriditing? Chemical conversion coating is an oxide film applied to the surface of aluminum whose main function is to act as an undercoating and base for organic finishes such as painting. It is considerably thinner than the oxide coating produced by anodizing and while adequate in protection against mild corrosion is hardly competitive with anodized coatings. The main attraction of chemical conversion finishes is the economy and speed with which they can be produced. The finish can be used as a temporary protective measure on parts which may require storage for an appreciable period or on parts where a conductive surface is needed with minimal corrosion protection. The finish is commonly called Iriditing or Alodining and can be clear to yellow in color. Our clear chromate is free from hexavalent chromium. Also meets RoHS compliance standards and QPL Approval for Mil DTL 5541F.