Anna, this is the first time I’ve heard of using Tarn-X as a pickle!
I use it to clean my brass, nickel-silver, and copper jewelry (if I
have not put a patina on them). I don’t think it is a sulfuric acid
solution – that’s a closer description of Sparex No. 2 and the Ph
Minus pool cleaner stuff (sodium bisulfate), which are commonly used
as pickles. Tarn-X would be a lot more expensive than other pickle
However, if you want to use Tarn-X, let me recommend storing it in a
Tupperware pickle-lifter (these have a bilious green, but
tight-fitting, top and can often be found at second-hand stores).
They have an interior plastic platform that you can lift up and down
– lift it up, put jewelry on, let it down into the Tarn-X, and lift
it up when “done” (in the case of cleaning off tarnish, a few
seconds). Use tongs to put jewelry into rinse water, then dry. For
cleaning, it’s very fast. If you want to continue using Tarn-X as a
pickle, you won’t have to bother putting it back into the jar all the
time. Hope this helps.