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. Do you have any ideas as to 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. Nickel barrier layer is oblique in or it is porous. In this will allow the silver to believe room 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.