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firing crystalline glazes with gas, ty for info

updated mon 12 nov 01

 

Yann Ferric on sun 11 nov 01


Hi Jen,

Thank you so much for the reply ,Im glad I can use gas
for the firing, as I can't use electric! :-D.

I haven't been doing much inc ceramics for a while, due
to depression etc , but am feeling alot better these days,
and it's calling to me again, hehe. It's something that gets
into the blood and stays there, totally addictive, so I have
decided to build a new kiln also, with the main aim of doing crystalline
glazes (but on a budget,lol). I love using gas
to fire the work,so this is great news, ty. I use propane,
and a raku torch I bought a few years ago, which I have used
to do stoneware also.
Once I have patched my present kiln up a bit I should be
ready to start some trials! Even though I will need to start
over for the new one after I get it built, but that
will be late next year and I can't wait that long:p, lol.

I'm mainly interested in growing a few big crystals on my
work (nothing like a challenge, lol)so I've been reading
the clayart archives too, and found some good advice to
start off with. I suppose it will be a while before I get
to see some, but it will be worth it, and the experimenting
is fun, like alchemy, hehe.

I will be starting off with flat pieces, like box lids,
and leaving vases or other tricky things to later.

The kiln I use now is a top loading oil drum type with a
flue at the top, but I imagine a cubic shaped kiln with
the flue at the side would retain a more even heat. So Im
thinking of designing one on that template to make next.
I use a pyrometer to work out the temp now, but I suppose
I will need to use cones for more accuracy.

love and light

Yann

This is a wonderful community! Just what I needed. :-D

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Michael Wendt on sun 11 nov 01


Yann,
I found that the top exit point on my Olympic style updraft (looks like an
electric 12 side kiln with burners under it) ran cold under the flue exit.
To overcome this, I place a kiln shelf at the top of the load with 1" of
Kaowool refractory fiber on top of that directly under the exit point. That
reduces the cold spot under the exit point. Be sure to allow clearance for
the flu gasses to escape.
In general, if parts of your kiln (like the lid) run cold, add kaowool
insulation to the outside of those areas and you speed the heating, slow the
cooling and even out the firing. WARNING: insulating the outside of the
metal jacket is a BAD idea. I put one probe of the digital pyrometer under
the blanket at cone 10 and found the temperature between the brick inside
and the Kaowool outside to be 1100 degrees Fahrenheit, hot enough to cause
significant expansion of the clamping band that holds this type of kiln
together. Instead, I made a new band that was bigger and put it around the
brick and insulation both. Slow cooling for crystals seems to help.
Good Luck,
Michael Wendt wendtpot@lewiston.com
you wrote in part:
The kiln I use now is a top loading oil drum type with a
flue at the top, but I imagine a cubic shaped kiln with
the flue at the side would retain a more even heat. So Im
thinking of designing one on that template to make next.
I use a pyrometer to work out the temp now, but I suppose
I will need to use cones for more accuracy.

love and light

Yann

This is a wonderful community! Just what I needed. :-D