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Steam casting


#1

Hi Gang,

I was going to jump in on this thread earlier, but this is my first
chance. As Rick pointed out, you shouldn’t me any more scared of steam
casting than any other form. Maybe even less scared than other ways
(like sling or centrifugal). It’s sooo low tech, that it’s usually the
least expensive way for the hobbyist to get into casting.

I have to preface this by saying that I haven’t actually
done this, but I’ve read about it, seen it done, and understand the
principles.

When investing your model, your sprue cone, or button, must be large
enough to contain the casting grain for the project, as the grain is
actually melted in the top (open end) of the flask. Since you don’t
want the molten metal to run down the sprue prematurely, it’s important
that the sprue not be to large… I think 12 ga. was the max.

The steam is created after the flask is burned out and the metal melted
in the top of the flask. A cap, containing water soaked material (like
a sponge or newspaper), mounted on a wooden handle, is pressed down on
the top of the flask when the metal is molten. The heat of the flask
and metal converts the water in the soaked material to steam, increasing
the pressure under the cap and forcing the metal into the cavity in the
mold.

Voila!

As a side note… I now send my stuff out to be cast. Saves me a lot of
time, expense, and potential frustration. No (few) bubbles on my
castings, no investment powder all over, no big expensive equipment, no
hours cleaning up castings… you get the idea. Very cost effective
when you factor in the time and successful casting rate.

Dave Sebaste
Sebaste Studio
Charlotte, NC


#2

Lane,

I have used steam casting with a prop/oxy mini torch in my
bedroom workshop with very good results. Primitive but a great
deal of fun. Managed to get 5 wax models of the same ring to
cast in the same flask. That was an unusual occurence. Contact
Dyer’s at 1 800 683 1631 for a “kit” for around $5It was worth
it.

Kathie Secor


#3

Steam casting can be a lot of fun. I used to mix my investment,
pour it into the flask that was sitting on a flat (aluminum foil)
surface. Then I would insert the wax from the top into the
investment and hold them in place with a “third hand” type
tweezer. The flask was filled to leave about 1/2" of room on the
to create the steam chamber. With a spoon I would make a shallow
indentation for the metal. Here it was important to pre-melt the
casting grain into one bulk, so that small pieces of metal would
not fall into the flask during the melting process.The sprues on
the wax were also designed to me smaller in diameter, and there
were at least two. After the burn-out, I would place the hot
flask on two bricks and melt the metal on top of the flask until
it rolled. I had prepared a (smile) lid from a mayonaise jar,
which I nailed upside down on a file handle. The inside of the
jar lid was then filled with water soaked card-board, which
almost looked like a putty at this point.As the metal is in its
liquid state, I would press the lid down on the flask. The wet
cardboard created steam, as well as a seal to build enough
pressure to push the metal into the flask. With a little
practice, some very good results can be achieved. It is too bad,
that that does not work for Platinum…

Should you need any help with working with Platinum, call me at the
PLATINUM GUILD INTERNATIONAL USA at (714) 760-8279
Jurgen J. MAerz, Manager of Technical Education,
JA Certified Master Jeweler


#4
Dyer's at 1 800 683 1631 for a "kit" for around $5It was worth
it.

Would that be Dyers in Austin Tx?


#5

Lane:

Several books talk about steam casting. If you are buying or
carving waxes and have even a small propane torch that the
handyman uses, al t other equipment can be homemade for steam
casting. Wykoff’s book on jewelry design is probably the best
source. E-mail if you want details on how to make the flask,
sprue base, steam caster, tongs, etc. Also instructions on how
to use a “flowerpot” burnout oven.


#6

Please send instructions. Lloyd


#7

Please email info :

E-mail if you want details on how to make the flask, sprue base,
steam caster, tongs, etc. Also instructions on how to use a
"flowerpot" burnout oven.

Thanks,
Maggie Morrell
@M3morrell


#8

Dear Fellow Jeweler

I would indeed like a copy of the steam casting you
have to offer.I am very interested in this method.

  Thank you very much	

                             LZ

#9

A great book that explains steam casting as well as other
casting procedures is Tim McCreight’s “Practical Casting - A
Studio Reference”. Very informative and has all kinds of great
tips for all phases of casting from model making to building
kilns to different casting processes.

Jill
@jandr
http://members.tripod.com/~jilk


#10

Maggie:

I just got finished redoing this stuff and putting it in my word
processor where I can get it out for you by export to the e-mail.
Thanks for your patience. Feedback welcome.

Steam casting eliminates the need for a centrifuge or vacuum
casting setup and substitutes a very inexpensive �steam
generator.� Metal is melted in a hemispheric cavity in the top
of the flask, eliminating the need for pouring and a crucible.
If simple, cheap equipment is desired, flasks can be constructed
from objects easily found around the house and burnout can be
accomplished, if through some trial and error, in a �flowerpot
burnout oven� placed over a hotplate. Investment and waxes
bought from suppliers will still be required (altho� any wax
could be used if you can work it satisfactorily), but most other
items can be scrounged or bought cheaply. Total cost for the
project could easily be under $40, depending on your patience in
haunting thrift stores and garage sales.

Flask — flasks for steam casting can be made from tin cans. A
good 2x2 inch flask would be made from a very small can of black
olive pieces with the top and bottom cut out with a can opener.
A more permanent flask could be made from a piece of 2 inch cast
iron pipe. Larger flasks could be made from larger cans or
larger pipes. In casting, the hot flask must be set on something
which allows venting of steam out the bottom of the flask. A
piece of porous firebrick (K-2) is ideal, or a cast iron pipe
nipple of a larger size than the flask with four or more holes
drilled in it could be used to set the pipe flask in.

Steam Generator — This is a very simple tool. A jar lid or
similar object with water soaked cardboard inside is held down
over the hot flask and molten metal, creating steam which drives
the metal into the flask through narrow sprues which hold out the
metal through surface tension until the steam pushes the metal
in. The steam generator can be made by screwing an
approximately 3/4 inch dowel (5 inch piece) into a quart jar lid.
Cardboard pieces of the appropriate diameter are soaked with
water and packed into the jar lid (3-4 thicknesses) to create the
steam. The dowel permits holding the jar lid down tightly for
one minute without getting burned. Leather gloves are a good
precaution, gardener�s gloves or cheap welder�s gloves, under
$10.

Mixing and pouring investment — investment is normally mixed
in rubber bowls so that the excess is easily pried out. Cheap
flexible plastic bowls should work OK. Investment can be mixed by
hand with a spatula or with an old hand held electric mixer. One
mixing blade and a fairly slow speed will do. One can make a
vacuum arrangement for deairing the investment with an old
vacuum cleaner. A bell jar for this purpose could be made from
an old three liter wine bottle. Cut off the bottom and sand the
edge flat with emery paper on a glass sheet and hook the vacuum
hose to a rubber stopper in the bottle. Find a way to rap on the
bowl and you are done. Another possibility is a vibrator such as
a vibrating finish sander with the bowl placed on the upside
down sander and rapped. simplest method would be the �hard
shell� method. A thick slurry of investment is mixed and painted
on the model with a brush. Once this investment has hardened, a
whole batch can be mixed and poured into the flask. No bubbles
because the model is hard shelled with the investment first. A
vacuum pump capable of both deairing and vacuum casting could be
made from an auto air conditioner compressor, but that is
another story.

Sprues and sprue base — As stated above, sprues are narrow
because the metal is melted in the cavity at the top of the flask
and must stay there until the steam forces it into the mold. A
good spru for this application is 14 gage, and they can be made
from wax wire or from regular size paper clips, which are the
right width. the sprue base is easiest made from modeling or
pottery clay formed into the proper shpe on a board or piece of
glass, with the spues stuck into it and the flask placed in
position before the investment is poured. The metal melting
cavity can be a one inch diameter hemisphere formed by the clay
sprue base. The sprue should be short, about 1/2 inch from the
cavity borttom to the model. If the model is large, several
sprues can be used to various parts of the model. Spruing is an
art, and perusal of what is written about it elsewhere will turn
up various general principles for placing sprues. Another option
is to add a button reservoir between the sprue and the model. Ths
is a small ball of wax about 1/4 to 1/2 inch in diameter
bisected by the sprue wire.

Burnout — Once the model is sprued and the investment is
poured (remember to consult your instrucions about the powder to
water ratio for investment, and remember that you will have a
total of about nine minutes of working time on the investment.)
you shouldproceed to burnout after about an hour or two of curing
the mold. To save money, burnout can be accomplished without a
burnout oven by using the �flowerpot oven�. find an appropriate
size clay flowerpot (6 to 10 inches diameter) and line it with
aluminum foil. Leave the flowerpot hole open for venting gases.
Burnout outdoors or in a very well ventilated space (gargae
w/door open, carport). To reduce fumes you could steam dewax,
getting out most of the wax before bruning it out. Steam
dewaxing can be accomplished by putting your flask into a
vegetable steamer instead of the broccoli, sprue side down. As
it steams, most of the wax will melt out. Then place the
flowerpot oven over the flask, with flask on a firebrick piece
or piece of mesh on top of the hotplate or gas burner. Regulate
heat by the hotplate control or by propping the flowerpot open at
first. The flask needs to be burned out for several hours, until
the throat of the flask is white, indicating that all residue has
burnt out. The top burnout temp is 1350F, over 1400F the
investment starts to break down. 1300F is where you can be
absolutely sure that the wax has vaporized. You can gage
temperature in several way. Dull red should be 1100F, cherry red
would be too hot, 1400F. A piece of sheet aluminum bend onto a
right angle will start to melt at 1220F. You can obtain pottery
cones which will bend over at certain temperatures; they can be
stood up in a pad of stoneware clay until they fall over. Your
pottery supplier can tell you which number cone is close to
1250-1350F. You can check the flask by lifting the flowerpot,
sticking a rod into the hole at about a 45 degree angle and
lifting. Try to hold your top temp without increasing for an
hour or so to complete the burnout.

Casting — Once the flask has reached about 1300F, you will let
it cool somewhat to reach about 1100 to 1140F, five hundred
degrees below the melting point of both silver and 14 kt gold.
This will show a dull red color in the throat of the flask in dim
light. Put your metal pieces into the cavity at the top of the
flask. Metal amount is determined by weighing the entire sprue
plus model plus button (Add a little wax to the top of the sprue
when you weigh, as you will want a �button� of metal left in the
cavity as a reservoir, at least a 1/2 inch size button.) before
investing. The weight of silver would be the wax weight times
10.4; of 14 kt yellow gold, 13.1. Don�t let the pieces be too
small or they will jamb in the sprue. Melt with an appropriate
torch (a handyman�s propane torch will do for making a ring or
two), add a pinch of flux (borax will do), and when the metal
looks as if it is rolling you might stir it with a carbon rod
($2-3) and then clamp the generator down for about a minute. A
good seal must be maintained or the steam will not force the
metal down. Sterling should not be quenched in a water bucket
to avoid hot tear. Just bang the casting out of the flask with a
rubber mallet and soak the casting in warm vinegar to clean off
the investment. Yellow gold can be quenched in a bucket of water
after the button loses its redness and the investment should
break up nicely and the casting can also be cleaned in vinegar.

Steam casting is said to produce detail about equal to that
obtained by centrifugal and some practitioners claim they can
cast about an ouce of silver in a flask. The cavity at the top
of the flask may need to be larger for larger flasks. Problems
can arise from incomplete burnout, too high or low a casting
temperature, or scorching (vaporizing part of) the metal in
melting. Incomplete castings may mean too low a flask casting
temperature or problems in spruing. When in doubt add a sprue to
an area that looks like it might not fill. It would be a good
idea to look over the description of casting practice in at least
one jewelry text, as many casting practices are the same no
matter whether casting is vacuum, centrifugal or steam. Let me
know how your experiment works out — you can e-mail me at
jess4203@aol.com


#11

Lloyd:

Sorry this has taken so long to put together. It is now in a
permanent file in the word processor, where I can export it to
E-mail. I got tired of typing it over each time. Hope it is
helpful.

Steam casting eliminates the need for a centrifuge or vacuum
casting setup and substitutes a very inexpensive �steam
generator.� Metal is melted in a hemispheric cavity in the top
of the flask, eliminating the need for pouring and a crucible.
If simple, cheap equipment is desired, flasks can be constructed
from objects easily found around the house and burnout can be
accomplished, if through some trial and error, in a �flowerpot
burnout oven� placed over a hotplate. Investment and waxes
bought from suppliers will still be required (altho� any wax
could be used if you can work it satisfactorily), but most other
items can be scrounged or bought cheaply. Total cost for the
project could easily be under $40, depending on your patience in
haunting thrift stores and garage sales.

Flask — flasks for steam casting can be made from tin cans. A
good 2x2 inch flask would be made from a very small can of black
olive pieces with the top and bottom cut out with a can opener.
A more permanent flask could be made from a piece of 2 inch cast
iron pipe. Larger flasks could be made from larger cans or
larger pipes. In casting, the hot flask must be set on something
which allows venting of steam out the bottom of the flask. A
piece of porous firebrick (K-2) is ideal, or a cast iron pipe
nipple of a larger size than the flask with four or more holes
drilled in it could be used to set the pipe flask in.

Steam Generator — This is a very simple tool. A jar lid or
similar object with water soaked cardboard inside is held down
over the hot flask and molten metal, creating steam which drives
the metal into the flask through narrow sprues which hold out the
metal through surface tension until the steam pushes the metal
in. The steam generator can be made by screwing an
approximately 3/4 inch dowel (5 inch piece) into a quart jar lid.
Cardboard pieces of the appropriate diameter are soaked with
water and packed into the jar lid (3-4 thicknesses) to create the
steam. The dowel permits holding the jar lid down tightly for
one minute without getting burned. Leather gloves are a good
precaution, gardener�s gloves or cheap welder�s gloves, under
$10.

Mixing and pouring investment — investment is normally mixed
in rubber bowls so that the excess is easily pried out. Cheap
flexible plastic bowls should work OK. Investment can be mixed by
hand with a spatula or with an old hand held electric mixer. One
mixing blade and a fairly slow speed will do. One can make a
vacuum arrangement for deairing the investment with an old
vacuum cleaner. A bell jar for this purpose could be made from
an old three liter wine bottle. Cut off the bottom and sand the
edge flat with emery paper on a glass sheet and hook the vacuum
hose to a rubber stopper in the bottle. Find a way to rap on the
bowl and you are done. Another possibility is a vibrator such as
a vibrating finish sander with the bowl placed on the upside
down sander and rapped. simplest method would be the �hard
shell� method. A thick slurry of investment is mixed and painted
on the model with a brush. Once this investment has hardened, a
whole batch can be mixed and poured into the flask. No bubbles
because the model is hard shelled with the investment first. A
vacuum pump capable of both deairing and vacuum casting could be
made from an auto air conditioner compressor, but that is
another story.

Sprues and sprue base — As stated above, sprues are narrow
because the metal is melted in the cavity at the top of the flask
and must stay there until the steam forces it into the mold. A
good spru for this application is 14 gage, and they can be made
from wax wire or from regular size paper clips, which are the
right width. the sprue base is easiest made from modeling or
pottery clay formed into the proper shpe on a board or piece of
glass, with the spues stuck into it and the flask placed in
position before the investment is poured. The metal melting
cavity can be a one inch diameter hemisphere formed by the clay
sprue base. The sprue should be short, about 1/2 inch from the
cavity borttom to the model. If the model is large, several
sprues can be used to various parts of the model. Spruing is an
art, and perusal of what is written about it elsewhere will turn
up various general principles for placing sprues. Another option
is to add a button reservoir between the sprue and the model. Ths
is a small ball of wax about 1/4 to 1/2 inch in diameter
bisected by the sprue wire.

Burnout — Once the model is sprued and the investment is
poured (remember to consult your instrucions about the powder to
water ratio for investment, and remember that you will have a
total of about nine minutes of working time on the investment.)
you shouldproceed to burnout after about an hour or two of curing
the mold. To save money, burnout can be accomplished without a
burnout oven by using the �flowerpot oven�. find an appropriate
size clay flowerpot (6 to 10 inches diameter) and line it with
aluminum foil. Leave the flowerpot hole open for venting gases.
Burnout outdoors or in a very well ventilated space (gargae
w/door open, carport). To reduce fumes you could steam dewax,
getting out most of the wax before bruning it out. Steam
dewaxing can be accomplished by putting your flask into a
vegetable steamer instead of the broccoli, sprue side down. As
it steams, most of the wax will melt out. Then place the
flowerpot oven over the flask, with flask on a firebrick piece
or piece of mesh on top of the hotplate or gas burner. Regulate
heat by the hotplate control or by propping the flowerpot open at
first. The flask needs to be burned out for several hours, until
the throat of the flask is white, indicating that all residue has
burnt out. The top burnout temp is 1350F, over 1400F the
investment starts to break down. 1300F is where you can be
absolutely sure that the wax has vaporized. You can gage
temperature in several way. Dull red should be 1100F, cherry red
would be too hot, 1400F. A piece of sheet aluminum bend onto a
right angle will start to melt at 1220F. You can obtain pottery
cones which will bend over at certain temperatures; they can be
stood up in a pad of stoneware clay until they fall over. Your
pottery supplier can tell you which number cone is close to
1250-1350F. You can check the flask by lifting the flowerpot,
sticking a rod into the hole at about a 45 degree angle and
lifting. Try to hold your top temp without increasing for an
hour or so to complete the burnout.

Casting — Once the flask has reached about 1300F, you will let
it cool somewhat to reach about 1100 to 1140F, five hundred
degrees below the melting point of both silver and 14 kt gold.
This will show a dull red color in the throat of the flask in dim
light. Put your metal pieces into the cavity at the top of the
flask. Metal amount is determined by weighing the entire sprue
plus model plus button (Add a little wax to the top of the sprue
when you weigh, as you will want a �button� of metal left in the
cavity as a reservoir, at least a 1/2 inch size button.) before
investing. The weight of silver would be the wax weight times
10.4; of 14 kt yellow gold, 13.1. Don�t let the pieces be too
small or they will jamb in the sprue. Melt with an appropriate
torch (a handyman�s propane torch will do for making a ring or
two), add a pinch of flux (borax will do), and when the metal
looks as if it is rolling you might stir it with a carbon rod
($2-3) and then clamp the generator down for about a minute. A
good seal must be maintained or the steam will not force the
metal down. Sterling should not be quenched in a water bucket
to avoid hot tear. Just bang the casting out of the flask with a
rubber mallet and soak the casting in warm vinegar to clean off
the investment. Yellow gold can be quenched in a bucket of water
after the button loses its redness and the investment should
break up nicely and the casting can also be cleaned in vinegar.

Steam casting is said to produce detail about equal to that
obtained by centrifugal and some practitioners claim they can
cast about an ouce of silver in a flask. The cavity at the top
of the flask may need to be larger for larger flasks. Problems
can arise from incomplete burnout, too high or low a casting
temperature, or scorching (vaporizing part of) the metal in
melting. Incomplete castings may mean too low a flask casting
temperature or problems in spruing. When in doubt add a sprue to
an area that looks like it might not fill. It would be a good
idea to look over the description of casting practice in at least
one jewelry text, as many casting practices are the same no
matter whether casting is vacuum, centrifugal or steam. Let me
know how your experiment works out — you can e-mail me at
jess4203@aol.com


#12

LZ — I think I missed sending anything to you — it is a long
explanation and i sent it out several times but aol dropped it
learned how to import it to a message. so, thanks for your
patience, et voila — I hope the whole thing comes thru.

Steam casting eliminates the need for a centrifuge or vacuum
casting setup and substitutes a very inexpensive �steam
generator.� Metal is melted in a hemispheric cavity in the top
of the flask, eliminating the need for pouring and a crucible.
If simple, cheap equipment is desired, flasks can be constructed
from objects easily found around the house and burnout can be
accomplished, if through some trial and error, in a �flowerpot
burnout oven� placed over a hotplate. Investment and waxes
bought from suppliers will still be required (altho� any wax
could be used if you can work it satisfactorily), but most other
items can be scrounged or bought cheaply. Total cost for the
project could easily be under $40, depending on your patience in
haunting thrift stores and garage sales.

Flask — flasks for steam casting can be made from tin cans. A
good 2x2 inch flask would be made from a very small can of black
olive pieces with the top and bottom cut out with a can opener.
A more permanent flask could be made from a piece of 2 inch cast
iron pipe. Larger flasks could be made from larger cans or
larger pipes. In casting, the hot flask must be set on something
which allows venting of steam out the bottom of the flask. A
piece of porous firebrick (K-2) is ideal, or a cast iron pipe
nipple of a larger size than the flask with four or more holes
drilled in it could be used to set the pipe flask in.

Steam Generator — This is a very simple tool. A jar lid or
similar object with water soaked cardboard inside is held down
over the hot flask and molten metal, creating steam which drives
the metal into the flask through narrow sprues which hold out the
metal through surface tension until the steam pushes the metal
in. The steam generator can be made by screwing an
approximately 3/4 inch dowel (5 inch piece) into a quart jar lid.
Cardboard pieces of the appropriate diameter are soaked with
water and packed into the jar lid (3-4 thicknesses) to create the
steam. The dowel permits holding the jar lid down tightly for
one minute without getting burned. Leather gloves are a good
precaution, gardener�s gloves or cheap welder�s gloves, under
$10.

Mixing and pouring investment — investment is normally mixed
in rubber bowls so that the excess is easily pried out. Cheap
flexible plastic bowls should work OK. Investment can be mixed by
hand with a spatula or with an old hand held electric mixer. One
mixing blade and a fairly slow speed will do. One can make a
vacuum arrangement for deairing the investment with an old
vacuum cleaner. A bell jar for this purpose could be made from
an old three liter wine bottle. Cut off the bottom and sand the
edge flat with emery paper on a glass sheet and hook the vacuum
hose to a rubber stopper in the bottle. Find a way to rap on the
bowl and you are done. Another possibility is a vibrator such as
a vibrating finish sander with the bowl placed on the upside
down sander and rapped. simplest method would be the �hard
shell� method. A thick slurry of investment is mixed and painted
on the model with a brush. Once this investment has hardened, a
whole batch can be mixed and poured into the flask. No bubbles
because the model is hard shelled with the investment first. A
vacuum pump capable of both deairing and vacuum casting could be
made from an auto air conditioner compressor, but that is
another story.

Sprues and sprue base — As stated above, sprues are narrow
because the metal is melted in the cavity at the top of the flask
and must stay there until the steam forces it into the mold. A
good spru for this application is 14 gage, and they can be made
from wax wire or from regular size paper clips, which are the
right width. the sprue base is easiest made from modeling or
pottery clay formed into the proper shpe on a board or piece of
glass, with the spues stuck into it and the flask placed in
position before the investment is poured. The metal melting
cavity can be a one inch diameter hemisphere formed by the clay
sprue base. The sprue should be short, about 1/2 inch from the
cavity borttom to the model. If the model is large, several
sprues can be used to various parts of the model. Spruing is an
art, and perusal of what is written about it elsewhere will turn
up various general principles for placing sprues. Another option
is to add a button reservoir between the sprue and the model. Ths
is a small ball of wax about 1/4 to 1/2 inch in diameter
bisected by the sprue wire.

Burnout — Once the model is sprued and the investment is
poured (remember to consult your instrucions about the powder to
water ratio for investment, and remember that you will have a
total of about nine minutes of working time on the investment.)
you shouldproceed to burnout after about an hour or two of curing
the mold. To save money, burnout can be accomplished without a
burnout oven by using the �flowerpot oven�. find an appropriate
size clay flowerpot (6 to 10 inches diameter) and line it with
aluminum foil. Leave the flowerpot hole open for venting gases.
Burnout outdoors or in a very well ventilated space (gargae
w/door open, carport). To reduce fumes you could steam dewax,
getting out most of the wax before bruning it out. Steam
dewaxing can be accomplished by putting your flask into a
vegetable steamer instead of the broccoli, sprue side down. As
it steams, most of the wax will melt out. Then place the
flowerpot oven over the flask, with flask on a firebrick piece
or piece of mesh on top of the hotplate or gas burner. Regulate
heat by the hotplate control or by propping the flowerpot open at
first. The flask needs to be burned out for several hours, until
the throat of the flask is white, indicating that all residue has
burnt out. The top burnout temp is 1350F, over 1400F the
investment starts to break down. 1300F is where you can be
absolutely sure that the wax has vaporized. You can gage
temperature in several way. Dull red should be 1100F, cherry red
would be too hot, 1400F. A piece of sheet aluminum bend onto a
right angle will start to melt at 1220F. You can obtain pottery
cones which will bend over at certain temperatures; they can be
stood up in a pad of stoneware clay until they fall over. Your
pottery supplier can tell you which number cone is close to
1250-1350F. You can check the flask by lifting the flowerpot,
sticking a rod into the hole at about a 45 degree angle and
lifting. Try to hold your top temp without increasing for an
hour or so to complete the burnout.

Casting — Once the flask has reached about 1300F, you will let
it cool somewhat to reach about 1100 to 1140F, five hundred
degrees below the melting point of both silver and 14 kt gold.
This will show a dull red color in the throat of the flask in dim
light. Put your metal pieces into the cavity at the top of the
flask. Metal amount is determined by weighing the entire sprue
plus model plus button (Add a little wax to the top of the sprue
when you weigh, as you will want a �button� of metal left in the
cavity as a reservoir, at least a 1/2 inch size button.) before
investing. The weight of silver would be the wax weight times
10.4; of 14 kt yellow gold, 13.1. Don�t let the pieces be too
small or they will jamb in the sprue. Melt with an appropriate
torch (a handyman�s propane torch will do for making a ring or
two), add a pinch of flux (borax will do), and when the metal
looks as if it is rolling you might stir it with a carbon rod
($2-3) and then clamp the generator down for about a minute. A
good seal must be maintained or the steam will not force the
metal down. Sterling should not be quenched in a water bucket
to avoid hot tear. Just bang the casting out of the flask with a
rubber mallet and soak the casting in warm vinegar to clean off
the investment. Yellow gold can be quenched in a bucket of water
after the button loses its redness and the investment should
break up nicely and the casting can also be cleaned in vinegar.

Steam casting is said to produce detail about equal to that
obtained by centrifugal and some practitioners claim they can
cast about an ouce of silver in a flask. The cavity at the top
of the flask may need to be larger for larger flasks. Problems
can arise from incomplete burnout, too high or low a casting
temperature, or scorching (vaporizing part of) the metal in
melting. Incomplete castings may mean too low a flask casting
temperature or problems in spruing. When in doubt add a sprue to
an area that looks like it might not fill. It would be a good
idea to look over the description of casting practice in at least
one jewelry text, as many casting practices are the same no
matter whether casting is vacuum, centrifugal or steam. Let me
know how your experiment works out — you can e-mail me at
jess4203@aol.com