I did a search on Google and found an article that referred to "an Iridite treatment". When a cadium plated surface is treated with an aqueous solution of formic acid and sodium dichromate, the process is commonly referred to as the Iridate treatment. I sourced details for the above at: http://www.google.com/patents?id=9QthAAAAEBAJ&printsec=description&zoom=4&dq=iridite#PPA2,M1