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Quench, Pickle, Rinse and Dry!
The instructions for most metalsmithing projects that involve the use of a torch for soldering or annealing include this cryptic phrase: quench, pickle, rinse, dry. But do we all really know the why of this phrase?
Cooling the metal eliminates the chance of a burn and ensures the metal is annealed to its softest state. We have found though, that quenching sterling silver at too high a temperature, say at “red heat”, most likely will cause the metal to crack and shatter. The result is a ruined piece, as you can see here. We have not encountered this problem working with copper and brass, but suggest you let sterling silver air-cool for at least 10 seconds before quenching.
Then it’s safe to plunge your metal into cold quench water.
The story is that medieval metalsmiths used a solution of alum and water to clean their metal after soldering and annealing. Alum was and still is used in cooking and converting cucumbers into pickles —thus ”pickling” the metal.
Even today, some metalsmiths continue to use alum to pickle their metal, others use a variety of solutions. These include diluted sulfuric acid solution ( very hazardous and not recommended), a citric acid solution and the jewellery industry favourite, a product called Sparex ( and so much safer to use!). Many use their pickle solution hot, conveniently heating it in a pickle pot with a glass lid or cover. Covering helps control the evaporation of the solution.
Do not make a practice of quenching hot metal directly in hot pickle — for several reasons. Doing so will splatter droplets of hot pickle all around the work area and generate a fine mist of pickle solution that will permeate the air. As this is the same air you breathe, the mist makes that air harmful to the lungs. Both the splattered droplets and mist also rust or corrode your expensive, shiny tools. Both cause small pinholes in your clothing and create the danger of causing chemical burns to your eyes, hands and arms.
That is why we recommend you always quench in fresh water first. Then place the metal into the pickle.
A NOTE ABOUT TONGS
Use copper , plastic, or wood tongs to place the metal into and out of the pickling solution, but never iron or steel tongs. Iron and steel will cause a galvanic action that results in a thin layer of copper plating onto your metal. If this plating should occur, just add a cup of hydrogen peroxide to the pickle pot and the resulting “super pickle” will quickly remove that plating. The hydrogen peroxide will not harm your solution, as it quickly reverts back to plain water.
Rinsing in clear water removes most of the pickle solution from the metal, but not necessarily all. Any residual pickle will still cause rust and corrosion of your nice, shiny, expensive tools, such as the rollers of your rolling mill — and there’s nothing worse than that! To avoid pickling your tools, after pickling your metal but before rinsing it, give it a quick dip in a neutralizing solution of water and baking soda.
Now rinse in clean water.
Finally, dry with paper towels.
Continue working off and polishing as normal.