FW: 18k White Gold

  . I have a casting problem. I have to deliver some 18k white
gold cast pieces in a week. I've done it before using a 75%Au
and 25%Pd alloy. It's very difficult, it wouldn't work in
gravity/vacumm so I had to reassemble my centrifugal casting
machine and even though didn't come up with something
satisfactory. I can't buy any alloy here and can't order from
any supplier because it wouldn't get here in time. I found
four different alloys in books, all of them have Copper, Zinc
and Niquel in different amounts. I don't have much time for
experiences right now. I wonder if I could add a little Tin to
lower the melting point. I can't use the centrifugal machine
any more, I don't have space. 

hi gabriel, 18k white gold alloys are specific to use as 18k.
meaning if you are using a 14k white alloy, it won’t be very
white. the specific 18k alloys used to make 18k white are all
palladium (as you’ve used) or all nickel with a little copper.
adding about 3% zinc would help to lower the melting point, but
it starts evaporating quickly if you are torch melting because
of the high heat. you can wrap the zinc in a thin 24k foil and
then throw it into your already melted charge. i would like to
mention that the problem with the high content nickel or
palladium alloy for 18k white is the high melting points of both
these metals ( the faulyt memory tells me about 2800 f) dont’ be
afraid to use

an oxidising flame to melt your charge. ther isn’t much copper
to oxidise in the alloy one should be using in this case. a
palladium alloy doesn’t require copper at all, copper adds more
ductility to a nickel alloy, but your palladium alloy is already
very soft and ductile. i would also suggest using a

wesgo platinum type crucible (fused silica), but this is not of
dire consequence. at the heat required to melt 18k white gold a
regular crucible can melt, imparting anoying inclusions into
your cast piece. also, if you are using the palladium only
alloy, don’t use borax. thouogh you don’t specify the

problem with your casting, most problems arise from dirty metal
(not enough new metal), too low of flask temp, or your metal not
hot enough when you cast.

don’t forget to anneal your piece after casting if you quench
cool at all. also alloy your charge before you cast to insure a
homogeneous mix. i can’t find my david fell catalog, but i did
find my swest metal catalog. their white alloy for 18k has
53.4% silver in it and the remainder is palladium and
“deoxidisers”.use zinc for the deoxidiser if you like. they say
the melting temp is 1950 f when alloyed, so… i would suggest
talking yur flask out of the oven at about 1250 to 1300 f and
get your prepared charge melted within 3 minutes.hope this helps
you. best regards, geo fox