Patent ID: 7569132

Claim:
A method of forming a protective coating on a surface of a metal article comprising aluminum or aluminum alloy, said method comprising: A) providing an anodizing solution comprised of water and one or more additional components selected from the group consisting of: a) water-soluble complex fluorides, b) water-soluble complex oxyfluorides, c) water-dispersible complex fluorides, and d) water-dispersible complex oxyfluorides of elements selected from the group consisting of Ti, Zr, Hf, Sn, Al, Ge and B and mixtures thereof; B) providing a cathode in contact with said anodizing solution; C) placing a metal article comprising aluminum or aluminum alloy as an anode in said anodizing solution; D) passing a current between the anode and cathode through said anodizing solution for a time effective to form a first protective coating on the surface of the metal article; E) removing the metal article having a first protective coating from the anodizing solution and drying said article; and F) applying one or more layers of paint to the metal article having a first protective coating, at least one of said layers comprising PTFE or silicone, to form a second protective coating; wherein the current is pulsed direct current.