Back to Ganoksin | FAQ | Contact

Using Antique Brass Mold?


#1

Hi Folks:

Here’s my question…and I thought you would know…

A good friend of ours (very knowledegable antiques dealer and French
& Indian War expert) has an early 1700’s -ish mold for original
trade silver… it is brass and about 1/8’ thick. He would love for
me to pour some silver pieces…but here’s my question…

This is a valuable piece and I do not want to hurt it. Can I safely
cast molten silver in a brass mold? It has 5 little hearts and
circles with a flat back piece and pouring spouts for each. So it
looks like a mold.! They don’t seem to fit tight enough so there
will be some air space and I imagine that this would allow the air
to escape. What do you think about this? Have people used cut brass
molds with molten silver? I am concerned b/c the melting point of
silver is higher than that of brass? But then again the brass is at
room temp and there isn’t a huge difference in melting point. The
brass has some kind of blackening…probably oxidized over the
years. The impressions are pretty small and about 2mm deep. What
keeps the silver from adhering to the mold? Do I need to worry about
a mold release of some sort?

My husband and our friend are very excited by the possibility of
trade silver from an authentic mold. But I do not want to ruin it.
Any ideas? I thought if anyone would know…you might. Thanks…for
any ideas or suggestions that you might have!

Barbara


#2

HI,

I haven’t heard of brass molds being used for silver casting although
I don’t see why they shouldn’t work. The blackening inside IS the
release agent - smoke or to be more precise, soot. If the mold is
cold then the silver should chill and its outer skin should harden
almost instantly. It may be that the mold would be dunked in water
quite soon after the silver had been poured. However, if you only
want something that looks like a silver bar, why not just use
plumbers’ solder. I have a couple of brass molds around somewhere
that were used for making lead models of Spitfire and Hurricane
planes just after the war and I have cast many models in these using
plumbers’ solder. In this case, the molds need to be a little warm or
the surface of the casting is wrinkled. Again I smoked them to
provide mold release. If you do make a silver casting I would be
interested to know the outcome - perhaps I will search out these
molds and make a few silver planes…

Best wishes,
Ian

Ian W. Wright
Sheffield UK


#3

I think this mold may have been for pewter instead of silver. Think
bullet molds. Considering its age and value I would not want to risk
molten silver. Also there is not enough mass there for the heat to
go somewhere. Is it a two part mold? I would do a wax cast then cast
the wax to get a metal master and make a new rubber mold. You will
have some shrinkage from the original but no chance of damaging it.

I have had brass molds for casting plaster ornaments for
architectural work. Several of the books in my library show molds
for tea pot handles and spout parts from that time period. Those
molds were in cast iron. Something to think about.

Bill Churlik
www.earthspeakarts.com


#4

Hi I just bought some Afghani brass molds I am going to use them to
make silicon molds to protect the antique pieces pour low melt wax
and then make a silicone mold.

Teri
Silver & Cameo Heritage Jewelry
www.corneliusspick.com


#5

Hi Barbara;

I’ve not seen silver cast in brass molds, but I suppose it would
work. If you try this, make sure the mold has been properly sooted
so the silver doesn’t stick to it. I believe you’ll have to heat the
mold to at least a couple hundred degrees F. for it to work. My
father used to work as a pewtersmith in an historical village crafts
program, and he used a lot of old brass spoon molds for casting
pewter (actually Britania metal, an alloy of tin and antimony, real
old pewter contained lead and is no longer in use). I wonder if your
mold wasn’t actually designed to be used to cast pewter. With
pewter, the mold would still get sooted, but the mold temperature
could be a lot cooler.

David L. Huffman