I've got an old kit with a flat piece of blackish glass and
bottles of liquid. The box label says it's a silver test kit. But
it came with no instructions so I've never used it. What is the
glass for? And does the liquid turn red on sterling silver? Or only
on fine silver?
The Troy Test I have just contains 4 bottles and a small booklet of
paper strips that look like blotting paper.
The kit you mention sounds like a touchstone kit. I’ve never used
such a kit, but understand that the method used is to scrape a the
black ‘glass’ with the metal to be tested, so as to leave a streak of
the metal on it. You then place a tiny drop of liquid from one of the
bottles on the streak, and watch the reaction. The liquids are
various acids that react with different results on different metals.
understand (someone correct me if I’m wrong) that the acid for
silver is nitric acid. The acid turns a shade of red depending on the
purity. Pure and Sterling silver are very red, but the reaction gets
browner as the grade gets lower.
The Troy Test has full details.
Regards, Gary Wooding