Palladium alloy casting questions

Several list members have warned against the introduction of carbon
with the use of graphite crucibles when casting palladium alloyed
white gold. Is it also a problem to probe the molten metal with a
graphite rod to determine its liquidity just prior to casting, or is
the carbon contamination of the alloy more a result of prolonged
contact with a graphite crucible? If one shouldn’t use a graphite
probe, what else is available and better? Tungston? Ceramic? Also, is
there a problem of excess carbon in the fuel using an oxyacetyline
torch if its a neutral or slightly oxidizing flame?

Thanks in advance.
Alan Heugh

http://www.nas.com/~aheugh/