vince pitelka on thu 22 feb 01
> So when is it safe to go back out there and work in a fairly poorly
> ventilated environment (which would be when I am trying to stay warm in a
> cold Michigan winter)?
The outgassing of toxic volatiles can continue throughout the firing, so
ventilation should continue as long as the kiln is firing. At low
temperatures you have sulfur dioxide, and at higher temperatures you have
zinc and possibly fluorine, lead (if any was present), and other materials.
Once the kiln has shut off there is no toxic danger at all, and you should
close all the ventilation and save that heat. Pipe it into your studio.
Best wishes -
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Rod, Marian, and Holly Morris on thu 22 feb 01
Here's one for the kiln ventilation discussion. My small skutt is in a 20 x
25 outbuilding with a door, a window, a sliding door and a woodstove. In
summer, I fire with all doors and windows open, and in the interim, I seldom
have the window closed. I never go out there when the kiln is on, or even
when it is cooling because it is just too hot to work.
Winter is different. I rarely have the doors or window open, except to crack
the window when the stove is burning. I fire at night with the window more
open, and sometimes crack the door and open the stove door to let maximum
air get sucked up the chimney.
But I ponder whether the outgassing of the fired clay continues while the
kiln cools down. Though I think I have ventilated the worst of it during the
heat-up phase, it seems to me that while the clay and glazes are still red
hot, they are still doing what they did before the kiln shut off.
So when is it safe to go back out there and work in a fairly poorly
ventilated environment (which would be when I am trying to stay warm in a
cold Michigan winter)?
Thanks, kiln gurus. Marian in Michigan, asking because of a looong period of
L. P. Skeen on fri 23 feb 01
> The outgassing of toxic volatiles can continue throughout the firing, so
> ventilation should continue as long as the kiln is firing. At low
> temperatures you have sulfur dioxide, and at higher temperatures you have
> zinc and possibly fluorine, lead (if any was present), and other
> Once the kiln has shut off there is no toxic danger at all, and you should
> close all the ventilation and save that heat. Pipe it into your studio.
Could you define your temperature ranges here? At my school, the kiln has
not been ventilated AT ALL until recently. The other art teacher fires it
on a regular basis to ^06, both with and without glazes. The kiln is in the
basement; the art room shares wall w/ the home ec teacher's room, and there
is a door between the art room and home ec. The home ec teacher recently
had blood work done and had arsenic! in her blood. She is exhibiting
symptoms of CFS, and I"m wondering if it could be because of the exposure to
Snail Scott on sat 24 feb 01
At 09:08 PM 2/23/01 -0500, you wrote:
>> Once the kiln has shut off there is no toxic danger at all, and you should
>> close all the ventilation and save that heat. Pipe it into your studio.
The materials in the kiln may have
ceased outgassing, but any fumes
emitted earlier are still in the studio
unless adequate ventilation was used!
Ron Roy on mon 26 feb 01
I'm not so sure there is not off gassing after a kiln is shut down.
When I fire my gas kiln - when I shut it down I still get readings on my CO
detector. I don't think the gases are coming from the kiln as I crash cool
for an hour and there is a negative pressure because the damper is still
What this must mean is the gases are still in some of the materials in my
studio. I assume - if you could measure the gases from an electric kiln you
would find some still there for a short time after shut down.
If you want to avoid most of them just continue ventilation for a half hour
after shut down.
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