Hazy Bright Acid Zinc Deposits

Q. We are having problems with our acid chloride bright zinc plating. We use a proprietary plating bath and are diligent about adding brighteners, wetting agent and other additives as required. The problem is that we are now getting a hazy deposit that does not respond to the addition of any of the vendor recommended additives. C. M.

A. It sounds to me like your acid chloride plating bath is ready for a serious cleanup and that means carbon treatment. I am surprised that your vendor has not recommended this to you. The process is not as nasty as it once was. You can obtain carbon-packed cartridges that are reasonably easy to work with. You should pump your plating solution through this cartridge (two cartridges in a series would be better) into an empty tank. Clean out the zinc plating tank and then pump the solution back into the tank. Rebuild the plating solution by adding the brighteners, wetting agent and additives. Before embarking on this task, check with your chemical vendor to determine if any special procedures are recommended.

You can find vendors of filter cartridges by accessing the Products Finishing web site, www.pfonline.com and looking under filtration equipment in the vendor database. While you are at the web site, look at the articles on acid zinc plating. The information will be very helpful to you.