Trying to stay on topic. at least this is related to ingots, forging,
etc… How do you keep the oxygen of of sterling silver to prevent
those pesky bubbles and firescale? I know the big boys do it in a
oxygen free atmosphere, but I don’t seem to have one of those handy.
I’ve tried to put a layer of charcoal on top of the scrap, but that
just blows off when I hit it with the torch and makes one big mess.
There is no real rocket science in reducing the oxygen content of
your molten silver alloys.
Prevention; melt with a good melt cover of charcoal or graphite. Do
not use the small brick type charcoal which is compressed dust, use
good quality lump wood charcoal.
Deoxidise; this can be as simple as immersing a graphite rod into
your molten metal and stirring. The commercial casters use
controlled additions of deoxidants such as copper-phosphorus, red
amorphous phosphorus or lithium. However you must be very careful
with this and an excess of phosphorus can make your silver alloy
hot-short and lithium is a highly reactive metal which requires
Protect; make sure that your molten metal passes through a lazy, gas
rich flame when casting to minimise any oxygen pick up during the
If you are having a problem with the charcoal flying everywhere when
you apply the heat from a torch then see if you can source some
graphite pieces which should be more robust.