Plating Q&A: Where Does My Silver Go?
Where does 10 percent of the silver we use go?
Q. We specialize in plating silver on electrical components. We have been monitoring the number of anodes consumed during a six-month period, and have discovered we are losing 10 percent of the silver when compared with the amount deposited. Over a six-month period, this is a large dollar amount. Where is this silver going?
A. In many old-time plating shops, silver and gold seemed to evaporate (particularly when the boss wasn't around). This problem is now history because of improved plating methodologies and better tracking of silver and gold plating bath components. Assuming this is not the issue, where may this silver be going?
Start by looking at the dragout in your plating processes. Each time a rack or barrel is removed from the silver plating tank, some of the plating solution adheres to the surface of the parts, the racks or the barrels. This solution must be returned to the plating tanks. Are you allowing a long enough drain time before going to the rinsing step? Look at how the parts are racked. Parts should be racked in such a way that the dragout can consolidate and drain from a single point on the part. Make sure your barrels are not overloaded. Overloaded barrels tend to drain slowly. Also look at the rinsing part of your plating process. Some of the plating solution will end up in the rinse water. This silver should be recovered. A silver-specific ion exchange system can also help you recover this material.
Don’t forget that silver is lost by plating on racks and danglers. Consistent stripping is essential. Filters also collect small amounts of bath components. Used filter media should be returned to your precious metal refiner for silver recovery.
Originally published in the September 2015 issue.
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