Hello all,
I have been trying to find out what kind of plaster to use for loss
wax silver casting without much success. The local supplier has all
of the plasters made by Laguna, so if anyone knows if theirs works
that would be very convienent.
Thanks for any help,
Patrick
try kerr satin cast. any decent jewelry supplier will have it, if
you can’t find one, call armstrong tool and supply,out of livonia,
mich. 800-446-9694. they will ship anywhere. good luck!
steve
arista designs
www.aristadesigns.net
I have been trying to find out what kind of plaster to use for loss wax silver casting without much success.
Patrick… You made my heart jump right up in my throat!!! PLASTER
is not INVESTMENT!!! You can hurt yourself real bad if you
centrifugal cast using plaster. It doesn’t have the strength of
investment and can easily blow the end out of the flask covering
everything with hot metal. Hopefully the caster is enclosed but even
then you could get badly burned. The old saying is “Hot Metal Hunts A
Bone”.
I would even hesitate to try slush casting with plaster. If it is
holding water…and you add hot metal… that makes steam… if the
steam is inside the plaster… BANG! you have a little explosion that
again…could cover you with molten metal.
If you are just starting out… which obviously, I think you are…
order yourself some Kerr Satincast 20 Investment. It isn’t expensive
and is made for casting.
Jewelry making is wonderful… but can be very dangerous! Acids,
flames, molten metal,… use all these with great caution.
plaster to use for loss wax silver casting
Patrick, this is one I said, “Let somebody else take it…”, and
then sometimes nobody else does. I have a suspicion that you are
confused - casting “Plaster” is not in any way the same as “Plaster
of Paris” type things, or stuff they put on walls or Frescoes. It’s a
special refractory (“High heat”) plaster made just for casting. We,
like many, use Kerr Satin Cast 20, which is available everywhere
jewelry stuff is sold. Many like Ransom and Randolph’s line - I’ve
never used them, myself…
I have been doing lost wax casting for over forty years in sizes from
single rings to 50+ pounds of bronze. Most of the time I have used
hydrocal plaster of paris–but not alone! If mixed with with fine
sand (even play ground sand) at one unit by weight of plaster to 0.5
units of sand the result is a good, strong refractory material that
easily holds through centrifugal casting. It should be burned out to
get rid of free water as well as some portion of bound water for at
least three hours at 1000 F. Thisis for a flask the size of a tuna
tin. My experience suggests that hydrocal/sand investments are
actually stronger that some of the commercial investments. On the
other hand, the commercial investments may give better resolution of
fine details (at far greater expense) unless you are very careful in
the investment process. The larger plaster/sand investments for
sculptural bronze or aluminum castings are fired at 1000F for at
least three days or more and easily tolerate the 2100+F. temperature
of molten silica bronze metal.
As another pointed out, a broken investment can (will) cause damage
from flying molten metal unless steps are taken to prevent it. My
centrifuge in mounted inside an old washing machine casing which
prevents injury in case of fractured investments or, as some of my
students have done, filling the melting crucible with more metal than
the investment can contain sothat the excess is slung away. I hope my
comments will be of use to you.
Gerald Vaughan, PhD
Vaughanart Foundry and Studio
Dan
Is there a ‘recipe’ for slush casting? How does it compare to
investment?
Tkx Simone