Dark spots appear on the backside of my sterling silver buckles after they age a bit. Noticeable because there is no engraving there. I pickle with diluted sulphuric acid (battery acid). Any suggestions would help. Thanks.
Hi Garcia,
That is sterling for you I think. The copper in the alloy tarnishes with a little moisture.
Sometimes it helps to pickle the buckle when hot and then burnish it but that is too much work.
The hot pickling creates a very thin fine silver surface and the burnishing wil close the pores.
Normaly the black spots will be easy to remove with a silvercloth with some polishing fluid.
If you have nasty deep black spots they will be firescale stains produced whenn soldering. If you use a good surface covering boraxlayer whenn soldering the stains will be a lot less deep or not there at all.
garcia;
First thing is to get rid of the Sulfuric Acid, use Spyrex, it's a lot safer, and does not tend to eat holes in clothes.
As for the oxidation, a quick, simple trick is, after polishing, is to use something like Pledge or equivalent furniture polish on it. It will stop the oxidation of the silver. The other alternative is to use something like Rio Grande, Midas Tarnish Shield.