Gold Stains Revisited
Those of you who read the item “Gold Stains” in the May 2005 column must be wondering what in the world I was saying! No, I was not trying to write directions for assembling a new barbecue nor did I "offshore" the proof reading of my column. I have repeated the question again with a non-garbled answer. I am sorry for the confusion.
Our company plates electronic components made of silver. The parts are nickel flashed and then plated with gold. We find that after a couple of days the gold becomes discolored. What might be wrong? C M.
Assuming your plating baths are all in good shape and not contaminated, the most likely cause of the staining is the nickel barrier layer. The nickel barrier layer may be too thin or it is porous. This will allow the silver to bleed through and cause the staining of the gold layer. Try using a heavier nickel flash.
One other possibility is that your nickel plating tank may be contaminated with copper.