Does this ever happen in your studio?
You (or someone else) unthinkingly plunges your (ferrous metal) tweezers in the pickle? Or, someone absentmindedly puts something in the pickle pot with (ferrous metal) binding wire on it. Either way, everything in the pickle pot is now copperplated.
Does that mean your pickle is “contaminated” and must be changed?
I have read in many sources and been told by many jewelers that once copperplating has happened in your pickle, it is “contaminated” and must be changed. The problem is, no one was ever able to answer my questions of what contaminated meant. Did it mean the pickle would no longer work? Could it damage my piece in some way? What negative effects could be expected? No one was ever able to answer any of my questions. That made me think it might be a myth, so I decided to test it out.
As it happens, my studio, Jewelry Arts Institute, does quite a bit of deliberate copperplating. One of the techniques we specialize in is 22k gold granulation. I’ll digress just a tiny bit for those who don’t know about how gold granulation is done. Granulation is accomplished by a technique called “colloidal soldering”. This means that the backsheet is heated and pickled a few times to raise a layer of pure gold to the surface. The granules or wires that are to be fused down are given a coat of copper in some way. This has a variety of possibilities, using powered copper carbonate, copper oxides, etc. The method we prefer as the neatest and most precise is copperplating in an acid bath. Copperplating in pickle works just as a basic battery does. Ferrous metal introduced into an acid solution creates an electrical charge. If the acid solution (the pickle we use is sodium bisulfate) has copper dissolved in it (as it will if you have been using it) the copper will be deposited on your metal. I was taught to take a small amount of used pickle, do my copperplating, and then discard the pickle.
I started testing in my home studio, copperplating in my main pickle and not changing the pickle afterward.
The copperplating stopped just as soon as I removed my tweezers or binding wire. My pickle then performed as it always had. It lasted for a few months, depending on how heavily it was used, just as it had before. It cleaned off oxidation in a few minutes, quicker when warm, just as it did before. I have never yet been able to discern any difference between how pickle acts if copperplating has or has not occurred. Once I was sure of my results, we started doing the same thing in the school pickle and the pickle acts as it always has.
So, stop wasting your time and money and just change your pickle when it needs to be changed!
For more useful tips and insights into how things REALLY work in the studio please take a look at my new book, Soldering Demystified, available on Amazon.com.