The sad truth is that the “safe” “organic” “natural” or “food grade” products sold as jewelry pickle are only all of those things BEFORE you use them. Even after you use them they are still (relatively) safe for you and your drains, but they are NOT safe for the environment. The retailers don’t have to tell you this because they aren’t selling you the used product, which is FULL OF TOXIC COPPER.
Fresh, unused jewelry pickle contains no copper. It is just a dilute solution of an acid like sodium bisulfate (Sparex®, Rio Pickle™, HTH® pH Minus – my favorite!), sulfuric acid, citric acid (PickleIt™), lemon juice, or vinegar. This changes dramatically after you use ANY type of pickle to clean your jewelry metals. ALL the different chemicals used as jewelry pickle are very effective at stripping copper oxides off your metal. As a result, pickle turns blue because copper molecules have been converted from solid metal into a contaminant in the liquid solution. Even pickle that has not turned blue yet is loaded with copper. The bottom line is this: If pickle has been used to clean metal, it is contaminated with copper.
Copper is extremely toxic to fish – 10 times more toxic to fish and other aquatic life than cyanide is to people!*
This copper contamination is NOT removed when pickle is neutralized with baking soda, so putting neutralized pickle down the drain is – from the perspective of a fish – like dumping cyanide into your local drinking water reservoir. If you dump copper contaminated pickle on the ground, it quickly leaches into the ground water, which is also very bad. It is extremely important that no matter where we live, we ALL dispose of this material carefully so as not to harm our fishy neighbors and further damage already beleaguered aquatic ecosystems!
Luckily, you have two GREEN choices for proper disposal:
Pickle Treatment – Precipitate Copper & Neutralize Acid
To treat your pickle yourself, you need to acquire 2 items that you probably don’t already have lying about the house:
- calcium hydroxide (pickling lime or slaked lime – sold in the canning section of some hardware stores, and also sold as Kalkwasser in some aquarium shops – NOT lime from a garden store, that has no calcium hydroxide) – I bought 2 pounds from Amazon.com (in re-sealable 1 pound bags). For my approx. 1.5 gallons of pickle, I used less than 1 pound of calcium hydroxide.
- pH test paper strips (get ones online or at a lab supply house that test from at least 1-12 pH with a color coded chart — soil and saliva pH test kits will NOT work!)
You will also need:
- kitty litter (cheapest – my experiment required about 10 pounds!)
- deep bucket (taller and deeper is best, rather than wide and shallow)
- small bucket or container (use to mix lime with water)
- stir stick
- splash goggles
1) Put on gloves and splash goggles.
2) Pour spent pickle into deep bucket, filling it not more than ¾ full.
3) Test the spent pickle solution with the pH paper. Dip just the tip of a short length of pH paper into the solution and compare it to the color coded chart on the pH paper dispenser. Make a note of the pH, which should be quite acidic (low number). Mine was at about a pH of 2 in the picture above.
4) Put a small amount of water (a couple of cups) in a small bucket or container. A pour spout is a handy feature here. Use a stir stick to mix in the calcium hydroxide (pickling lime) until you have a smooth slurry.
5) VERY SLOWLY – I repeat VERY SLOWLY!!! – add the lime slurry to the spent pickle and stir with a stick. If you pour quickly, it is very easy to add too much lime, and shoot past the desired pH of 9.
6) When the color changes to green and the solution starts to get cloudy, check the pH again. It’s coming along nicely and I’m at a pH of about 7 in the picture above.
7) You want to continue (SLOWLY!) stirring in small amounts of lime slurry (and testing frequently with the pH paper) until you reach a pH of at least 9 (solution will be basic now rather than acidic). The final solution must have a pH of between 9 and 10, or you won’t pull all the copper out of solution and turn it into solids in the form of the cloudy precipitate.
In the picture above, the pH test strip has reached the blueish-green color that indicates a pH of 9. So YAY for that :)!
To show you what you DON’T want, this picture shows a strip of pH paper that has been dipped directly in the calcium hydroxide (lime) slurry. You can see the white lime on the end of the paper. Just behind the bit of lime, the paper is a dark blue, indicating a pH of 13, which is WAY too high.
You don’t want to go past a pH of 10, or the tricksy copper will go back into solution. If that happens, all is not lost! Mix up a bit of fresh pickle and add it to your big bucket. This will drop the pH again, and you can have another go at creeping stealthily up on the desired pH by adding more lime. The fresh pickle doesn’t have copper in it, of course, but the additional acid will get you back on track. Test your pH again before adding any more lime. In fact, test your pH OFTEN, you have a whole roll of pH paper, and that’s what it’s for :).
8) Once you’ve reached a pH of 9 or 10, let the bucket of cloudy solution sit undisturbed overnight. The solid precipitate (copper hydroxide particles) will settle to the bottom.
If the liquid above the settled solids is transparent, then you have successfully removed all the copper. If it’s still blue or green, then there is still copper in solution, and you’ll need to check the pH and adjust up (with lime) or down (with pickle) to get to a pH of at least 9 and no higher than 10.
It’s hard to tell whether the liquid is clear when you are looking down into a bucket with a layer of GREEN precipitate at the bottom, so I gently and carefully scooped a bit of the liquid layer out with a small white plastic container (pictured above). Yep. It’s clear! On to the final steps!!
9) Gently lift the bucket and ever so carefully pour the clear liquid off, leaving some liquid and the solids in the bottom of the bucket. The clear liquid can go down the regular sewer/sink drain (not storm sewer!).
10) Allow the remaining liquid from the resulting sludge to evaporate — or mix with kitty litter to form a solid. The precipitate and liquid left from treating about 1.5 gallons of pickle required around 10 pounds of clay-type cat litter to absorb all the liquid.
Bag the dry solid result and dispose of in trash.
EPILOGUE: You very probably have some of your calcium hydroxide lime slurry left over. You can either store it in its slurry form – properly marked as “Calcium hydroxide – corrosive slaked limewater” – until the next time you need to treat spent pickle. It keeps well. Stir it up before using it again. Since it’s a strong base, don’t store it near acids. If you don’t want to store the slurry, you can pour small amounts – a pint or less at a time – down your toilet.
What I did was let the slurry dry out completely, and then broke it into chunks and put it back into the bag it came in to store it. It keeps well this way, too, and is ready for the next time I need to treat some pickle.
That’s it. Done and dusted!
Thanks for caring, standing with the planet, and protecting all the fabulous life in the water around you.
P.S. Did a friend forward this post to you? Did you stumble on it by accident? Want to eliminate the element of chance? Click here to get on my direct list.
P.P.S. (added 3/24/16) Here’s a nice graph of the theoretical solubility of metal hydroxides vs. pH, which shows a really clear low point on the line for copper (Cu) at pH 9. This is why knowing the pH is so important, since the copper begins to go back into solution above pH 9.
*Dave Waddell from Local Hazardous Waste Management Program in King County, WA, told me about the toxicity of copper to aquatic life, and taught me this method for treating jewelry pickle. Dave can be reached at (206) 263-1673, and at firstname.lastname@example.org.
Sadly for us, Dave is retiring on June 24th, 2016. He will be much missed by the arts community he has done so much to help! He urges people to contact King County’s Business Waste Line for help and information. Their number is (206) 263-8899.