I would lke some advice on improvised molds. For example instead of
cuttlefish could something like soapstone be used for a simple mold
for silver" I know it is used to line woodstoves so it should handle
heat but wonder if it should be pre-heated before dumping molten
metal on it. There are other soft stones that are easy to carve like
alabaster and catlinite, has anyone used any of these" Any help with
this would be appreciated. Rick (on top of a mtn. in TN.)
Solderite soldering boards, being very flat and heat reflective, are
easy enough to carve designs into, and pour metal into for an
"improvised" mold. This works well for longer forms, like cast
bracelets, or even wire ingots. C-clamps can be used to hold the
boards together vertically, and the melted metal is poured down a
sprue channel carved between the boards. Often the boards will hold
up well enough to pour a number of castings in the same carving.
Hey there, I’ve done brass casting in an open fire with a mould
carved out of a rock pulled out of a garden… as long as you
pre-heat it (and it survives that much) in thoery it should work,
soapstone is used for pewter all the time.
Just remember if you undercut anything the piece is never going to
come out.
I would lke some advice on improvised molds. For example instead
of cuttlefish could something like soapstone be used for a simple
mold for silver" I know it is used to line woodstoves so it should
handle heat but wonder if it should be pre-heated before dumping
molten metal on it. There are other soft stones that are easy to
carve like alabaster and catlinite, has anyone used any of these"
Any help with this would be appreciated. Rick (on top of a mtn. in
TN.)
I’ve cast tons of pewter in soapstone, but for silver, I would
preheat (soapstone can and does absorb ambient moisture), and be
prepared for the mold to fail; and don’t expect more than a couple of
clean casts at best. I definitely wouldn’t try it with alabaster or
pipestone (catlinite).
a few years ago I went on a one day course with a guy at a place
called Butser Ancient Village, in the UK, which was an experimental
farm for trying out historical theories to see if they worked.
He was casting bronze axe heads about 4" long and he was using 1"
thick pottery kiln shelf cut down into blocks. The shape was ground
out of the two halves and he had some kind of locks to register them,
I can’t remember what. The core was carved out of soft firebrick and
had to be replaced for each one. He cast about ten of them, and apart
from the first couple when he had to make the mould a little larger
in one place because it was not filling at that spot it worked very
well.
At the end I think he had a little spalling on the mould but not
much. I still have the one he cast for me.
If you go into local museums you can see half axe head moulds, I
have never seen both halves. They say that they were used to make
waxes but I am sure this is wrong, archeologists come up with a
theory and then rarely test it. This was the enlightening thing about
Butser,they could never say for sure how something was done but they
could prove a theory wrong.
I had the same idea awhile ago I think that the stone especially
alabaster would have to be pre-heated slowly even still with
moisture loss the likeliness of the stone cracking is high I do not
know about soapstone but alabaster may cause more problems depending
on what you use I have some pink colorado perhaps i will done my
respirator from hades and try it lol
Tufa or sandstone is a mold material used by the SW indians to cast
silver. Google search Tufa molds and for soapstone molds for pewter
search Soapstone molds.
As to catlinite, I know that type metal (lead/tin/antimony blend)
was “inlaid” into incised undercut areas of calumets (peace pipes). A
much lower melt point and very little shrinkage.
He was casting bronze axe heads about 4" long and he was using 1"
thick pottery kiln shelf cut down into blocks. The shape was
ground out of the two halves and he had some kind of locks to
register them, I can't remember what. The core was carved out of
soft firebrick and had to be replaced for each one. He cast about
ten of them, and apart from the first couple when he had to make
the mould a little larger in one place because it was not filling
at that spot it worked very well.
Yes, there is ample evidence from the remains of casting apparatus
and some surviving treatises that baked clay molds were a pretty
common technique in the medieval eras. De Re Metallica (ISBN
0-486-60006-8) and The Pirotechnia (ISBN 0-486-26134-4), both from
the 16th century, give some pretty good ideas of what they were doing
by the time metal casting was a pretty mature technology. On Divers
Arts (ISBN 0-486-23784-2) is much earlier (11th century) and his
metal casting techniques were fairly advanced by then. Pretty much
anything earlier than that is from archeological finds. They’ve found
a lot of metal working materials in the digs in York, England, and a
couple of the Scandinavian sites.
20 years ago or so there was an exhibit at I believe the Met in N.Y.
called the gold of El Dorado. Part of the exhibit catalog discussed
the techniques used by the Incas for casting Gold and Silver objects.
The process they used was to create a model of wax, add a large
sprue and then coat the item with a loose clay slip and then they
would encase it in a clay vessel very much like a vase with a wide
opening at the top. After the mold dried they would melt out the wax
over a fire and use the mold to cast gold or silver.
Tufa or sandstone is a mold material used by the SW indians to
cast silver.
I use tufa for some of my casting. It is unrelated to sandstone.
Tufa is a volcanic material similar to pumice. Very easy to saw and
carve. It would more appropriately be called tuff.
You can get Tufa Stone from Thunderbird Supply, Gallup, NM. Go to,
The Colorado Academy of Silversmithing and Art Metal. http://users.frii.com/dnorris They have a complete write up about
tufa stone casting.
Is tufa (or tuff) a one-time-only casting material? What kind of
surface does it produce?
Noel, I don’t have the experience, but my bibliography on the use of
tufa molds lists Sprintzen (Jewelry: Basic Techniques and Design) p.
68, Choate (Creative Casting), p. 98, Maryon (Metalwork and
Enamelling), p. 200ff. and Chamberlain (no title listed!) p. 81
Kathryn Palochak (on this list) knows about tufa molds.
My father uses Santa Fe Jewelry supply to get his Tufa. He does and
interesting thing, that as the mold deteriorates through maybe 5
castings his design changes.Instead of looking at it as
deterioration he looks at it as new designs. This may last through 3
more castings until the mold is not usable. Oscar Branson’s books
talk about tufa stone and show photos of the process. I always
thought that sand casting would be the way I would go, then each
mold is fresh but the pieces are one of always. The master can be
made and the sand pressed against it to make multiples or the sand
can be carved for each design. This is one of those techniques I
want to try as well as enamel. I LOVE this career, so much to learn.
I bought mine there as well…and now after 6-7 years and hauling it
halfway across the country, this discussion has got me wanting to do
something with it…ah, the magic of Orchid to inspire!
I have used soap stone for multiple castings in sterling. I have a
form which has cast at least 20 pieces and shows no sign of wear till
now. I just cut out the form, oiled it slightly, and cast. First
casting in a series normally is not very good and detailed, but the
first casting heats up the form and the next castings turns out very
well.
On the other hand I once had a very bad experience. A very good
friend of mine carved a very intricate form in a white soap stone and
I looked forward to make some castings of it. However, first time I
tried casting it, it simply cracked with a lot of noice the moment a
tiny splash of molten silver hit it and was absolutely spoiled. From
that on I always try to heat the soap stone with a torch, before I
commence any work on it. I have been successfull wilt soap stone of
Norwegian origin and have also some success with material from
Greenland and Newfoundland.
So, happy carving, but check the stone first.
Niels Lovschal
Contemporary and Viking Age Jewellery
Classes in Jewellery Techniques
Bornholm, Denmark