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Gravity casting pewter?


#1

Hi,

I have a friend who asked me how she could make gravity cast pewter
pendants at home. She is a capable, artsy crafty person but not a
metalsmith. Although I’ve worked as a goldsmith all of my life I’ve
never made anything out of pewter. I imagine you could probably cast
it right into a RTV silicone mold or spin cast it in one way or
another? I’m looking for a fairly low tech method, start to finish.

Thanks in advance,
Mark


#2

High temp silicones work fine so does cuttlebone and also regular
investment casting. The silicons and investment casting will
generally give you superior detail. It is relatively easy to melt
(stove top) but it is hot enough to really burn. Be careful of
"pewter" alloys containing lead, not good to melt and really not
good for direct skin contact. Spin casting is probably the way by far
the most pewter items are cast these days.

John Dach


#3

Hi Mark,

It is so low melt point that you can cast into plaster of paris.

***Note: It does help to warm the mould in an oven though.

Regards Charles A.


#4
It is so low melt point that you can cast into plaster of paris.
***Note: It does help to warm the mould in an oven though. 

Best to do more than warm it. Any residual moisture can cause a
steam bubble that will throw molten pewter around, not a good
scenario. For jewelry scale molds heat the plaster to at least 300
degrees F for an hour to make sure the water has been driven from the
mold.

Jim

James Binnion
ames Binnion Metal Arts


#5

you can cast into many different low tech molds. I have cast a number
of objects in plaster molds, but also into wood, cuttle fish bones,
and metal ones.

My simple plaster - silica ones utilize a standard casting plaster
mixed with a very fine silica sand as a filler.

My patterns for these usually are made of either modeled or carved
wax. Models are carefully made with no undercuts and with a little
molding draft. The resulting plaster molds are carefully cured
(dried) and then slowly heated to eliminate all un reacted water.
They must be cast preheated.

Closed two piece molds can be used but need vented to get full
filling.

for the lower melting materials the molds can be used several times
Molds like this can be used for metals melting at aluminum and lower
temperatures. They also work for kiln cast glass.

A very simple technique.
jesse


#6
I have a friend who asked me how she could make gravity cast
pewter pendants at home. She is a capable, artsy crafty person but
not a metalsmith. Although I've worked as a goldsmith all of my
life I've never made anything out of pewter. I imagine you could
probably cast it right into a RTV silicone mold or spin cast it in
one way or another? I'm looking for a fairly low tech method, start
to finish. 

Pewter is easy but messy. You can melt it in a steel or cast iron
ladle with a butane torch and pour it right into an RTV mold. It fills
details nicely as long as the mold is well vented with lots of air
vents leading diagonally upward from the model. However, the mold
needs to be clamped/taped on the lower edges or else the thin, runny
pewter will come right out the bottom. You need to have dedicated
tools for it, as it contaminates everything it touches.

Kathy Johnson
Feathered Gems Jewelry
www.featheredgems.com


#7

Hi Jim,

Best to do more than warm it. Any residual moisture can cause a
steam bubble that will throw molten pewter around, not a good
scenario. For jewelry scale molds heat the plaster to at least 300
degrees F for an hour to make sure the water has been driven from
the mold. 

Depends how much you use, the size of the plaster mould, and how dry
the plaster is. Pewter is pretty much a doddle, of course you are
correct it’s better to have a warm mould, although I have moulded
pewter in a cold mould with success. I used to make a lot of model
soldiers out of pewter when I was eight.

I did make a model of a demon head I saw in a movie, around about
the same time, and instead of using pewter I used lead, and the
plaster mould was quite large, about the size of an eight year old’s
fist. I didn’t let the plaster dry long enough, and poured the molten
lead into the mould. Result lead volcano. I didn’t make that mistake
again. I used to cook the plaster a little after that.

Plaster is something you can use for pewter, and can be quite safe
if you take care. However Dowe Corning has some very nice RTV that is
flexible, which is a big plus over plaster.

Regards Charles A.
P.S. I consider a kitchen oven “warm” :wink: