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Homemade burnout kiln


#1

Hi orchid, does anyone have details about using a flowerpot/hotplate
for wax burnout? i was reading an old thread where someone said that
they had good results with that, but they gave no details or
instructions. thanks


#2
    Hi orchid, does anyone have details about using a
flowerpot/hotplate for wax burnout? 

Never tried it myself, but here’s a link to instructions:
http://users.frii.com/dnorris/steamcast5.html

Janet


#3

It’s not complex, so don’t worry about whether you’ve got it exactly
right. Take one of those red clay (terra cotta) flowerpots, and line
it with a decently thick layer (maybe an 1/8th inch or a bit more, of
furnace tape. The stuff used to be made of asbestos, and isn’t now,
but it’s still now a fire resistant (once the binders burn off) and
insulating material. Wet it to form it, and let it dry. Cover the
furnace tape with a layer or two of aluminum foil. Place this over
the top of your flask, on your stove or hotplate, and turn it on.
Temperature regulation and burnout time are figured just by eye. a
gas burner will go quicker, but even a simple electric hot plate will
do it, given enough time. As I recall, something on the order of 8
to 12 hours worked just fine. This is the method mentioned in
publications describing the steam casting method. With a casting
"machine’ that amounts to a jar lid nailed to a bit of broomstick,
and lined with either wet newspaper or wet furnace tape, and a
burnout kiln made of that flowerpot, it’s likely the only thing you
might need to buy, and maybe not even that, is the furnace tape for a
few dollars, the investment mix (your casting flask can be a steel
tin can (don’t use an aluminum one), and a torch of some kind. And
the hardest part, once you figure the sequence out, and figure out
how to correctly sprue for steam casting, is the little detail, the
second time around, of convincing the “significant other” in the
house that you should be allowed to make that smokey mess of the
kitchen again (meaning, the first time, don’t forget to turn on the
vent fan over the stove. And if you’ve a decently clean looking
stove, be prepared to replace the burner liner. That little chromed
dish thing under the burner. K-mart or Target or the grocery stores
sell em. It will get a bit gunky from the burning wax… Expect the
whole process to take you a few tries before you learn it and figure
out it’s quirks.

Peter


#4

A hotplate and any sort of heat resistant pot with a lid will do
Place two lengths of 2x2 timber in the bottom of a pot, mine is an
old pressure cooker with the valve removed. Fill to below the
surface of the timber top and place the flask upside down on the
timber. Replace the lid and heat to boiling and leave for around
20-60 minutes depending on flask size. I have a photo on my
website which demonstrates this under “How to cast jewellery”

Alan Lewis
www.watchrepairer.co.uk


#5

Years ago when I started out in this pursuit, I used the flower pot
and hotplate burnout method and it worked just fine for me. I
stacked two clay flower pots, lining the bottom one with heavy
aluminum foil. I then set the “flask”, ( a small juce can) on the
hotplate, covered with the pots and turned it on. Simple as that.

Jerry in Kodiak


#6

Hi,

does anyone have details about using a flowerpot/hotplate for wax
burnout? i was reading an old thread where someone said that they
had good results with that, but they gave no details or
instructions.

If I remember correctly an article appeared in Lapidary Journal a
loooong time ago that described the set up. To the best of my
recollection here are the main points.

  1. Get a single burner electric hot plate with a burner about 8
    inches in diameter. (A double burner would probably work as well.)

  2. Find a clay flower pot that’s just large enough to cover the
    burner when it’s placed on the burner upside down.

  3. Before using the flower pot, cover the outside with a layed of
    aluminum foil. The heavy duty type would probably work best. A hole
    can be made in the foil where the hole is in the flower pot.

  4. Place the flask to be burned out on metal pan that’ll fit inside
    the flower pot. It helps if the flask is supported aprox. 1/4 inch
    above the pan. 3 or 4 nails can be placed between the pan & the edge
    of the flask.

  5. Center the pan & flask on the burner. Cover with the aluminum
    clad flower pot.

  6. Turn the hot plate on. It’s best to put the hot plate outside or
    some place where the smoke/fumes from the wax can dissipate without
    causing a problem.

Sorry, I can’t give you any time requirements for the burn out
cycle.

Dave


#7

Check out this message in the Orchid archives. It describes the
burnout kiln made with a flowerpot.

https://orchid.ganoksin.com/t/steam-casting

#8

There have been some excellent posts already submitted regarding
making a flowerpot burnout kiln. I just want to add a few
suggestions. It is a smelly process, so unless you have no other
alternative try to burn outside or in your garage. It can be done
inside, on your kitchen range, but you should have the hood fan on
to assist with the exhaust of the fumes. This is a noisy nuisance,
will smell horribly,and the soot will cover your cabinets.

Be sure to elevate your flask. A small piece of firebrick (about 2
inches square) should be placed under one rim of the flask ,
tilting it slightly. Place it so the the dish side of the flask is
downwards so that the wax can flow out., You can burn out more than
one flask at a time by placing them around the disk of firebrick.

The amount of time needed for the burnout will vary depending on the
heat output of your range,and the type of wax used. If I remember
correctly I used to allow 4 hours. You can judge whether the
burnout is complete by the chalk white appearance of the investment.
Also, there should be a red glow radiating in the dish part of the
investment, and the little sprue chanels will glow sort of orange
red. Examine them in a dim light as they will not show up clearly
in a bright light.

When lining your clay flower pot with foil, put the dull side
against the pot and have the shiny side facing outward so that it
will radiate the heat toward the flask. Use plenty of foil so that
you totally cover the inside of the pot as will as bringing it
well up over the outside of the clay pot. Use heavy duty foil, or two
layers of the thiner foil. Also be sure to poke a hole in the foil
so that the bottom of the pot will be open and the fumes can excape
from it.

One important point is to select a size of flower pot that will
totally cover the heating coils of your burner thereby directing
all the heat to the inner part of the flowerpot. You don’t want the
pot to rest on the coils,but to extend out over them and rest on the
burner.

Good luck. Alma


#9

Hi All:

This may or may not apply to you’re project but I thought it
interesting! Years ago I built my own forge and was helped by a
sculptor who worked at N.A.U. He showed me how to make a five part
refactory mix that would line the firebox on the forge. It consisted
of equal parts of Portland Cement,River Sand,Vermiculite,Sawdust and
Fireclay. It was all mixed in a wheelbarrow with a little water until
when pushed around it would clump up good and stay in position. Then
we took a 2x4 and rammed it into the firebox frame (angle iron and
sheet steel)and trowelled it off to shape. After the initial firing
of the forge(coal fired) the refactory was cured and did not crack or
breakdown in any way. The forge used a squirrelcage blower for air
and was controlled by a footpedal rheostat with a butterfly valve
for controlling airflow. It worked super and would heat up a round
steel blank (2"x6") in about three minutes to white hot. Anyway the
refactory held up great. Hope this is of use to anyone who needs
material like that. It can be formed into sections and asssembled to
whatever configuration you would want.

Best Wishes
Harry


#10

super quick question here re: flower pot burn out kilns. Does this
metihod get the investment hot enough to cure and harden properly?
If so, why do we take a flask to 1350 F during a regular kiln burn
out cycle? Thanks,

Danny


#11
   super quick question here re: flower pot burn out kilns.  Does
this metihod get the investment hot enough to cure and harden
properly? If so, why do we take a flask to 1350 F during a regular
kiln burn out cycle? 

Danny, i your hot plate or stove burner is adequate, you’ll find that
the flask under that hot plate WILL have reached a similar
temperature range. heating the investment to 1350, by the way, is not
to cure or harden it. Anything much over about 350 degrees will have
done that (taking the temerature past the quartz inversion temp) with
crystobalite based investments. (phosphate bonded platinum
investments need to get hotter, as the investment must partially
sinter for proper strength. This doesn’t happen with the standard
investments). The reason for that temp range is that it’s about the
hottest one should get such investments before one runs increased
risk of the stuff starting to break down. And getting it that hot
ensures a full burnout and removal of carbon residues. If you steam
dewax, then there are much fewer residues, since little wax actually
soaks into the dry investment to carbonize, and lower burnout temps
will work just fine. And in the flowerpot, lower temps would also
work fine if the time is extended enough so the investment looks
fully burned out.

Peter