I may have missed some things here, but I wanted to clarify
something. Any ‘pickle’ solution is acidic. It becomes heavy with
copper (even when the particles are not viewable with the naked eye).
Steel dumped in the solution causes the copper particles to adhere to
the metal in the pot much like what happens in plating processes. I
do not remember the nature of the process, but can go through my
notes to explain more.
I use ordinary vinegar as a pickle as well, and have had a situation
where the copper plated some silver and sterling I had in it because
I grabbed the wrong tongs (steel, not the copper ones). The variables
appear to be the amount of copper in the metals or in the liquid from
previous pieces, the amount and length of time steel is in contact
with the solution, and heat.
I don’t know anything about the liquid used by the original poster,
though it might contain some sort of pickle-ing agent. If there is
steel shot, sterling silver (not argentium) or copper, and an agent
such as vinegar (or other chemicals…not noticed with lemon juice),
there is a possibility of plating (we’ve planned to and have managed
to use this when we’ve soldered copper (using sterling solder) to
plate the copper over the solder seam. (to do that we waited until
the pickle needed to be changed, after a lot of sterling and copper
pieces had been in the pickle so that the liquid was closer to
saturated, then did it, as the process isn’t always as successful
when little copper has been dissolved in the solution.
Anyone know what is in the product by Rio Grande?