but there appeared little holes in one area. Anyone with have any
idea what the origin of these might be from my description?
You probably had defects in your original cast bar. Little bubbles
of trapped impurities or oxides or even air, or small shrinkage
cracks/voids… Things like that. When you then heat it with the
torch, some of these will burst just like bubbles. They may also be
the underlying reason why you got cracks in those areas in the first
Silver, for what it’s worth, is sometimes harder to get a good ingot
or bar with than it seems. Rolling good sheet metal from a cast
ingot, for example, is something I find a lot harder to get with
sterling silver than with, say, yellow golds. Very often, by the time
I get the sheet rolled down to a reasonable thickness, when I then
anneal it, I get some blisters showing up as bulges in the sheet.
These are areas where absorbed gas pockets, or other impurities,
which spread out during rolling, expand on heating. Annoying. When I
make sterling sheet metal, I just assume I’m going to get some bad
areas in the sheet, and plan on needing to work around them. Wire is
a bit easier to make, since those same types of defects when rolled
and drawn to wire, don’t end up as spread out blisters, but rather
threadlike long inclusions, generally down the middle of the wire.
That can still cause problems if it’s more than minor, but often the
wire is still usable.
The fix is that you’re ingot or bar pouring routine needs to be a
rigorous as possible in eliminating causes of these defects. Melting
furnaces seem to work better than torch melting, at least for me, and
the temperature of the ingot mold is important too, to get proper
progressive solidification of the bar without forming shrinkage gaps
in the center. If the metal you use has been used several times
already, then steps to deoxidize it are useful. Proper fluxing of the
melt, or addition of deoxidizing agents like a little phos-copper
can help too. But even with your best efforts, you’ll likely still
get occasional defects.