cast iron… hmm, I personally avoid iron, in all forms, anywhere
near fine silver and even low karat golds ( 14-18). I don’t use
anything but stainless, tungsten, titanium, tantalum and copper
studio tools and am ultra careful when something is ferrous but its
use is unavoidable to contain any dust or particles, etc. generated
if the task involves abrasion of any kind… Iron is an insidious
contaminant particularly when working silvers. Unless the iron
itself is used as a part of the design or as an alternative, and
intentionally used metal I try to avoid anything containing it. One
time I alloyed a quantity of gold- I used the same crucible I always
used for 22karat golds, the same charcoal and ammonium sulphate
refining powder I blend, but the gold came out so incredibly tough
that it took more than 20 minutes to anneal to a half-hard state,
never acheiving dead soft temper, and was almost resistant to
rolling. I wanted to find out what happened since I keep an
unbelievably clean and over-the-top organized studio. and am truly
concious of ferrous metals entering the space- I had taught a class
a few weeks before and all the gold sweeps and filings were in the
batch I was processing. I used a magnet over the waste as always,
and it extracted a bit of a saw blade. All I could presume was that
the magnet missed some teeth off of the blade(s) that ruined the
whole pour. I remelted it and made grain, which went directly into
aqua regia. After a wait all the impurities dissolved out of the
gold, and I had to start again…I learned my lesson. and lost most of
the day’s work time. A friend and colleague that recently passed
away, DX Ross, shared the same philosophy about iron contaminants in
the studio -with equal vigilance so I knew I was neither alone nor
over reacting.!
I would, at least, put a barrier between the cast iron and your work,
even though you aren’t soldering on it, why risk contamination? it
can be as simple as a sheet of parchment or transfer (graphite) paper
taped down so it doesn’t shift when you are burnishing… otherwise I
would look for a glass topped hot plate at a garage sale, or thrift
store if you must use an electric hotplate. I have a sheet of
stainless steel, about a quarter of an inch thick, and keep it on a
tripod over an alcohol lamp to heat the surface, the grate on the
tripod acts as a diffuser for the heat…It works well, is
multi-purpose (for truing bezels, straightening or flattening soft
metals, etc.) and saves power. RER
