Aluminum is a very pourous material and it is in the pores where the oxide layer is formed.  Anodizing is the process of chemically forming an oxide layer with the aluminum at varying thicknesses, depending on the end use.  This “coating” thickness hardens the surface of the aluminum and protects it from the elements.  Typically, the layer penetrates the aluminum and builds the surface at the same rate.

The anodize process starts with Pre-Treatment (cleaning).  The rack of material goes through an Alkaline cleaning tank and a series of rinses.  Then onto an Acid cleaning tank and a series of rinses  The typical bath temperatures can range form 140-170 degree.

Once the material is cleaned, it is ready to be Etched in a Sodium Hydroxide (caustic soda) bath.  The typical bath temperature ranges from 130-145 degrees.  This prepares the aluminum to be anodized by taking off a thin layer of aluminum and is what gives the aluminum its “natural” or matte appearance.

After this step, the aluminum can take on a film, and must go through a De-Smut (weak acid) solution to remove the “smut”.  Then onto the Anodize tank where it is submerged into a Sulfuric Acid solution.  The typical temperature for this solution is between 65-70 degrees constant.  Depending on the coating thickness required it will remain in the bath anywhere from 30 minutes to an hour before going through a series of rinse tanks.

After rinsing takes place, there is the Sealing Process. This is where the pores are closed and the aluminum becomes nonabsorbent and protects the outside finish.