I have worked with sterling silver for 25 years but recently
encountered a new problem. I ordered a sheet of sterling from a
different supplier as the one I usually use could not deliver before
Xmas. I cut out shapes for earrings and drilled a hole for the
earwire. Domed them in my doming punch and polished and cleaned. I
did not anneal so no heat on the metal. The final cleaning was with
a JCR cleaning system which does a final clean like nothing else.
Everything looked great. I make these earrings regularly and have
had no problems in the past.
A week after making I noticed black spots on the metal half a mm and
smaller. At first I thought that some how I had cross contaminated
from the doming punch, but on closer inspection the black spots are
also on the edges which did not touch the punch. Also one of the
pieces has a brown tarnish on the back. I re-cleaned them and other
pieces with the JCR as I regularly do with my stock. The black spots
remained and the brown tarnish was still there on one piece.
Are there impurities in the metal? This bullion dealer boasts of
recycling silver and I have been told by those who have used this
supplier (after I purchased the metal) that assay is true but metal
quality is inconsistent.
My solution would be to pickle and polish but am worried the black
spots will return. But I want your advice before I do this as this
knowledge base is greater than any one person, which is why I think
Ganoksin is the best. What do I do if I can’t get the black spots
If I return the metal I loose labour and lemel. I have sold some
pairs, before the black spots appeared, and may have to deal with
Is this a case of stick with the quality you know or have I stuffed
up somewhere in the making process?