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Burnout temps for casting stones in place


#1

Hi, does anybody have the recommended burnout cycle for casting stones in
place? I’m also interested in whether any of you cast in place with
palladium white gold, and what you do to compensate for the higher melting
temp. Thanks, Mike.


#2

WE have had real good results for burnout at 900 degrees F. Do not go
above this temp and this is what you will cast at. You will have to
experiment with the palladium white gold.

Russ


#3

Are you saying that your burnout temp never goes above 900 F? I though
the investment needed a higher temp to completly cure/fire. Can you give us
a complete burnout temp-time table? This is something I have been going to
try.

Lorri


#4

Russ How do you eliminate the carbon from the mold at such a low
temperature? It will not burn away below about 1100 F . If you have any
carbon in or near the mold surface you will end up with gas porosity in
the cast metal.


@jbin
James Binnion Metal Arts
4701 San Leandro St #18
Oakland, CA 94601
510-436-3552


#5

Mike, I watched a video on casting with stones, tried it once with
success. Here are a few specs:must be a gypsum based investment in which
you put 1to2% boric acid, temps for dia,c-z’s…1000 to 1050 degrees,950 to
1000 for other non perishable gems, metal casting temps 150 to 200 above
liquious temp,.The burnout is the key…300 degrees for 2hrs, 500 2hrs 950
10 to 14 hrs. This hardens the investment and burns out everything without
damaging stones, cast and let flask cool 1.5 to2 hrs, then carfully break
away investment. Let me know if you need more inf. Thomas Blair


#6

Lorri, The highest temp is 900 to 950 degrees, but you leave it in the
burnout for 10 yo 14 hours. That will certinly “cure” the investment, the
point being not to overheat or “frost” the stones. Thomas


#7

Hi Lorri, I tried it last night and it worked beautifully with channeled
princess diamnonds in palladium white gold. I went to 212 for an hour, 500
for an hour, 750 for an hour and then topped at 900. The investment looked
a little funky like it usually does on those quick burnouts, but it cast
just fine. Life’s lookin’ good, eh? Mike


#8

This burn out cycle doesn’t reach the carbon vaporation temperature of
1200f. Are there additional porosity problems? And what do you do to
over come them?

I’m searching my back files for MJA issue on casting stones in place.
This is several years ago and will update w this info soon.
Marcus Amshoff


#9

Dear Lorri: Just so you understand, the 900 deg F threshold is to protect
the stones. We need to compensate with a longer hold at this temperature.
The higher temperatures in a typical burnout (1350F) is to insure the
removal of the wax as carbon. Steam dewaxing is an alternative but this
adds moisture to the formular that can have adverse effects.But as I
mentioned before, there is a great product from R&R called "Solitaire"
which allows you a higher top end temperature (up to 1300F) without harming
the stones.RG


#10

I have successfully cast CZ’s in bronze sculpture and in jewelry sized
pieces using shell molding techniques. The investment is burnt out in a
type raku kiln in about 20 minutes to above 1200 degrees F no control on
rate of rise or final temperature, but shell is cherry red. The investment
will handle steel and stainless steel so gypsum based limits don’t apply. I
leave the poured mold cool down in air as slow as it wants to before
breaking out. This works with the synthetic flawless faceted stone- no
problems.
Jesse


#11
This burn out cycle doesn't reach the carbon vaporation temperature of
1200f.  Are there additional porosity problems?  And what do you do to
over come them?

Beleive me it does work but several things must be done good mixing of
boric acid powder(about a spoon full for a three by four inch flask, never
go above *1250 temp, make sure you have cleared enough wax away from under
the stones for small pedastals of plaster will support your little stones
abouve and from underside when the wax is gone or stones will fall and be
embedded in the metal somewhere where you most likly will not find them,
be carful when moving from oven to casting position so as not to bump or
drop and move stones from position, make sure that stones do not overlap
or touch tightly or chipping will happen, I have found that when doing
channels that alittle extra wax for a rim abouve the stone allows you to
work metal down to a nice clean edge and not get that frothy problem that
some times happens around edges of settings. And I just for my own good
feeling make knive edge girdles( Bag. and princess at points) Its not hard
to do but I do not do anything that I can’t afford to replace in case
something happens( like big stones - They hold heat much more). Try syn.
stones first and get your feet wet.
Ron Kreml