DULL ZINC DEPOSIT
Q. We plate zinc using an alkaline non-cyanide zinc plating process. Our deposits never seem to be as bright as the finish some of our competitors process. Do you have any suggestions on how we can improve the appearance of our zinc plate? A.R.K.
A. Your e-mail does not give me much to go on, but I can provide some general information for you to think about.
To start with: Are the parts that you are comparing your results with plated in the same type of zinc plating bath? Acid zinc plating baths can produce brilliant, bright deposits. These deposits have been known to fool the unwary into thinking they are decorative chrome. Alkaline zinc baths can also produce bright deposits, but in my experience not quite the same as the acid zinc plating baths.
Do you analyze your plating bath on a regular basis? You should have a complete analysis performed, not just the zinc concentration. I assume you are using a proprietary brightener or brighteners in your bath. Have you contacted your chemical vendor to see what suggestions they may have? I know this may seem hard to believe, but many chemical vendors can help you solve problems. You just need to ask.
The last point is this: If you can’t come up with a solution to your problem you might consider using a different type of zinc plating bath and/or a new chemical vendor.