Q. Can deionized water cause dullness in hard gold plates? The gold plate is 100-200 micro-inches thick. We find that if the plating solution is made up with distilled water instead of DI water the deposit comes out nice and shiny. Do you have any thoughts on the cause of this problem? H.M.
A. Assuming that both plating solutions are made up with identical raw materials and the plating process is identical in both plating baths, the only thing that comes to mind is the purity of the DI water that you are using. Typically, distilled water is more expensive on a gallon-to-gallon basis so there is an economic reason for using DI water. Do a check on your DI system. How often do you change resins? Perhaps the piping system requires a thorough cleaning. Last, but not least, have a laboratory analyze for various heavy metal ions and other possible impurities at very low concentrations.