One of our customers has recently started to complain about pitting of wire parts that we bright nickel plate. We have compared our recent results with those of a year ago, and our customer is correct. The parts we plated a year ago did not have this pitting problem. Our customer did admit that it recently changed vendors for the wire used in the parts. Could this be the cause of the pitting? R.B.
Yes. What most likely is happening is that impurities are embedded in the wire during the drawing process. These impurities show up as pits during the plating process. Although you do not state this, I bet the pitting you see is essentially along a straight line.
Your best bet is to convince your customer to use a better grade of wire for his product. The alternative is to anodically treat the parts in a 35-50% sulfuric acid dip. This treatment will probably clean the surface but you will have to apply a heavier bright nickel deposit to obtain the required bright finish.