Pickle is an acid solution that jewelry artists use to remove flux and the oxidation called firestain that results from heating metals. It works incredibly well, but when handling any chemicals, safety is extremely important.
If you haven't set up a pickle solution before, it is straightforward if you follow these steps: always add water first, Sparex granules second, and stir gently with copper tongs to avoid splashing. Wear gloves when handling pickle granules, and always wash hands immediately afterwards as a precaution.
If you get pickle on your skin, rinse immediately and thoroughly with water. If any pickle is spilled, neutralize the spill by sprinkling it with baking soda before wiping it up while wearing gloves.
Heat makes pickle solution work faster than at room temperature. Many silversmiths use a crock pot on low for this purpose. Note: pickle should never be boiled. Always turn off your crock pot when finished. Leaving it on will cause the solution to evaporate and could crack the ceramic insert.
If you are just starting out and don't want to invest in a crock pot used exclusively for pickle, you can mix pickle in a glass jar and use it at room temperature, it will just take longer to work. Instead of five minutes, it may take more like 20 or 30 minutes to remove firestain.
It is important to only use copper, brass or wooden tongs in the pickle solution. Using steel tools in pickle will result in copper plating everything in the pickle at that time. Usually this is an unwanted effect, but sometimes you can use it to your advantage when you need to plate a piece in copper.
Why does this happen? Here is how: With extended use, pickle will eventually turn blue, which is an indication of copper ions suspended in the solution. The bluer the solution, the more copper is suspended. Introducing steel to the mix creates an electrical charge that coats any piece of metal in the pickle with the copper ions, effectively plating it. As soon as the steel is removed, the charge is gone and the plating reaction ceases. Pickle is perfectly good to use after the steel item is removed.
Once you use pickle in a crock pot, it cannot be used for food again. Our personal preference is the Little Dipper crock pot, available at stores such as Target and Bed Bath and Beyond. Its small size takes up very little room on our work table. Label your pickle crock pot so it is clear it is not food-safe. A skull and crossbones sticker on the side is an effective sign.
Store pickle in the crock pot or glass jar with a lid to prevent evaporation in a safe place. If a significant amount of water evaporates, you can replace it by very carefully adding more water. Pickle can be reused until it turns blue, at which time it becomes ineffective and is called "dirty."
To dispose of pickle, contact your local toxic/hazardous waste agency to find out standards for your community. Many often have hazardous waste collection days throughout the year. We like to store used pickle in glass jars and let the liquid evaporate until it is time for our city's next hazardous waste collection day. It is much easier to transport dry crystals than liquid acid.
If you city allows disposal of used pickle in the sewage system, you must neutralize your acid before pouring it down the drain so you do not damage your plumbing. Used pickle has copper suspended in the solution, so only dispose of it down the drain after you have confirmed with your hazardous waste authority that your local water treatment facility can handle heavy metals.
Neutralize your pickle in a well-ventilated area by placing the crock pot insert or glass jar holding the pickle in a large plastic container, like a bucket, in the likely case it overflows. Slowly pour baking soda into the solution, which will bubble up just like the volcano experiments you did in elementary school. Keep pouring baking soda until there is no more reaction. Rinse thoroughly with water and pour down the drain.