i was just reading todays ganoksin email and i got to the bench
tips survey part with the "small melting jobs" part, could someone
explain what sal ammoniac will do to silver scrap
The ammonium chloride reacts with baser metals to form metallic
chlorides, such as tin, zinc, or iron chloride, etc. These are
insoluable in the metal, so they slag off with the melting flux. The
ammonium chloride, by the way, doesn’t melt to a liquid flux, but
skitters around on the molten surface turning to noxious vapors, so
use it with good ventillation. The :“vapor” is of course, chlorine
gas, which is toxic, but which is also what is reacting with, and
helping remove, the contaminant metals. The charcoal powder you add
is a reducing agent to lessen oxygen absorbtion and oxides. The combo
essentially act as partial refining fluxes, a helpful effect when
remelting/reusing scrap metal. Note that with gold casting alloys,
this will remove, at least partially, the deoxidizing agent, zinc,
that is often intentionally added, so the refining flux is not always
what you will want to use in melting depending on the metal and use.
, it also says about mixing it with charcoal 1:5, were can i buy
this sal ammoniac
Chemical supply houses. Sometimes found in tiny bottles to supply or
resupply hobby chemistry sets from hobby shops. The stuff is not
expensive. Sal ammoniac is an old/obsolete name. Ammonium Chloride is
the proper chemical name.
and then its mixed with the charcoal and you add it to the scrap
how much do you add before you melt the metal
A pinch, once the metal is at least starting to melt. doesn’t take
much. I usually add it, if using it at all, after the metal is fully
molten, and I pour as soon as most of the flux has dissipated and the
surface of the molten metal has “cleared”.
Peter