Steam dewaxing

Hi Jeff,

Steam Dewaxers should really only be used for waxes with melting
temps up to 190 degrees F. which would include injection and
sprue waxes. The steam will quickly and easily melt out these
waxes.

But carving waxes melt at 220 deg. (soft, blue), 230 degrees
(med, purple), and 240 deg. (hard, red). The steam is not hot
enough to melt these out completely. I think of carving wax
patterns as kind of trapped and “simmering” inside the mold - not
technically accurate I’m sure - but allows you to visualize what
it is doing to the investment. Little bits of investment break
away and what you end up with is a casting with a VERY rough
surface finish and rough lumps of extraneous metal where the
investment broke away more severely.

Since carving waxes all need to be hard wax in order to carve
them, they all have high melting temps well over 190 degrees F.
and should not be steam dewaxed.

Hope that helped answer your question.

Best Regards,

Elaine Corwin
GESSWEIN CO INC USA

Jeff, Hi. I have found that a profesional grade pressure cooker
works quite well for dewaxing: just make sure you use the one
that has locks all around the top,the tem. and presure gage is
acuarate,and your pressure realese valve works. Adjustment of you
heat source may be needed to assure a constant tem. and presure.
45 min is plenty of time for 3 to 4 3.5x4.5 flasks.

Good luck
Ruben Yanez

Jon:

Interesting. However, how do you prevent your steel-encased
kiln from rusting out from the inside? If you will notice, most
steam dewaxers have stainless or aluminum cabinets for just that
reason. Aside form the heating unit, this is the leading cause
of death in kilns.

Best;
Steve

    Jeff, Hi. I have found that  a profesional grade pressure
cooker works quite well for dewaxing: just make sure you use
the one that has locks all around the top,the tem. and presure
gage  is acuarate,and your pressure realese valve works.
Adjustment of you heat source may be needed to assure a
constant tem. and presure. 45 min is plenty of time for 3 to 4 
3.5x4.5 flasks.  

More questions on this one.

When using a pressure chamber pressure IS tempature. So, 45
minutes at what Pressure ?

thanks.

HI Orchid, I am considering steam dewaxing as a solution to thefumes
and mess of burnout. Also since I seem to be having trouble
completely eliminating carbon from my flasks despite what should
adequate burnout times and temps, I’m thinking that steam dewaxing
may be helpful. So my question is how do I need to adjust my burnout
after dewaxing? Do I put them directly into the oven while still hot
from the steam? What temp should I start them at in the oven? I’ve
heard of problems with investment failure after steaming, what would
cause that? Thanks, D.

Hi Doug,

The first thing you need to know is that steam de-waxing doesn’t
work with carving wax. Carving wax has too high a melting temperature
and steaming it causes some strange things to happen that will ruin
your casting.

Injection and modeling wax work just fine.

You really don’t need to make any adjustments to the burnout cycle
if you steam the investments first. It won’t completely eliminate the
wax, so there are still fumes. But there will be a lot less stink and
soot.

I use Satincast-20. The instructions say wait at least 2 hrs after
the investment has set up before starting burn out. I like to give it
2 hrs before steaming, but one hour seems works OK. One hour in the
steamer does it.

Somewhere I picked up the instructions that you should go from the
steamer into a hot kiln, at the low end of the burn out ramp. I
learned from an Orchid thread several years ago that this bother was
not the least bit necessary. Now typically I will stem out the flasks
in the afternoon and set the kiln to start at 10 or 11 PM. There is
no problem letting them cool to room temp. But if you are in a hurry
you can go from the steamer right into the kiln at 300F.

I have a commercially built steam de-waxer but I used to do it with
a big stock pot on a hot plate. To do that you need to have a rack
that holds the flasks above the boiling water. However you do it, be
careful you don’t boil dry or boil down to where the heating elements
are above the water in a steamer. I did this once and it caught fire.
It set off the fire alarm for my security system. The security
company dispatched the Fire Department, even though I was right there
and had the fire out in a couple minutes. The casting still worked
just fine. No harm done to the investments but it somehow ruined my
smoke detector and being a hard-wired part of my security system
meant I had to pay several hundred dollars for a service call and
repair.

Steve Walker

I have never bothered with steam dewaxing and I get a good clean
burnout with maximum burnout temperature of 650C for a minimum of 1
hour. I have the kiln and my vacuum casting equipment in an outside
shed. I just run the fan and open the windows during burnout and
casting and just check on things occasionally until the wax is
mostly burnt out at around 500C after which I can close the vents on
the kiln and take the temperature up to 650C. After the soak time the
sprue cavity is white (beneath the red glow) or slightly grey. Good
sprueing gives a good burnout.

All the best
Jen
Jenifer Gow

it caught fire. It set off the fire alarm for my security
system.... it somehow ruined my smoke detector and being a
hard-wired part of my security system meant I had to pay several
hundred dollars for a service call and repair. 

I’ve been told that any time a smoke detector “smells” smoke and
goes off, you must then replace it or it will have false alarms
thereafter.

Paf Dvorak

I've been told that any time a smoke detector "smells" smoke and
goes off, you must then replace it or it will have false alarms
thereafter. 

Not quite that extreme. Oily smoke will definitely contaminate smoke
alarms and smoke detectors; but your typical “I burnt the bacon”
smoke isn’t as bad. Typical consumer grade smoke alarms, should be
replaced between 7-10 years (the sensing element breaks down, with
time); system grade smokes like the ones installed on security
systems and fire alarm are much tougher and better designed, and with
proper care and maintenance can last 2-3 times as long,

Ron Charlotte
Gainesville, FL

Somewhere I picked up the instructions that you should go from the
steamer into a hot kiln, at the low end of the burn out ramp. I
learned from an Orchid thread several years ago that this bother
was not the least bit necessary. Now typically I will stem out the
flasks in the afternoon and set the kiln to start at 10 or 11 PM.
There is no problem letting them cool to room temp. But if you are
in a hurry you can go from the steamer right into the kiln at 300F. 

The kiln temperature has minimal effect on the investment till the
water is all evaporated out of the flask. The internal temperature
will remain 212F till all the water is gone so as long as the
temperature is around 300 that will keep the water evaporating out.
Trying to force it to go faster by raising the kiln temperature can
actually cause problems if the difference in the kiln and the flask
gets too extreme.

James Binnion
James Binnion Metal Arts

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