Silver is Too Hard

I am a “lurker” who has had many potential questions answered before
I could ask them. I have not seen anything on a problem I
encountered this past week so if anyone can help I would appreciate

I was making my first attempt to pour a silver wire ingot in an
attempt to make some wire. I used a new crucible that I fluxed with
boric acid powder. Using an ounce and a half of sterling scraps I
successfully melted the silver and poured it into the cast iron
mould that had been oiled with mineral oil and heated slightly. I
kept the flame on the silver at all times during the melting and
while pouring to prevent oxidation.

Here is the problem. The ingot is so hard that I could only saw it
with great difficulty. Tried to stamp it with the sterling stamp and
it would not make an impression at all. I tried annealing it in a
kiln at 1200 degrees for 15 minutes than cooled it slightly, than
put it into pickle. I now have a silver ingot that acts like mild
steel, it will not bend or flex and is impossible to run it through
a mill.

Any ideas on what may have happened will be appreciated.

Ronald Neldner

Dear Ronald

Welcome to this one of the nicest forums on the www, or should I say
THE nicest.

Years I experienced something very similar and found out that my
melt had been contaminated with tin. Even very minute parts of tin in
your silver will make it extremely hard (and brittle). Could that be
the case?

Niels Lovschal
Bornholm, Denmark