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wood in gas kiln...experm.results

updated fri 31 jan 97


Peggy Heer on sat 25 jan 97

Hi everyone...I promised before Christmas to post my experiment
results...."wood in gas kiln" ...after the new year so here it is.
Remember the thread??????

Reason for experiment and original inquiry......
I was hoping to be able to smoke my pots using my gas kiln and insert wood
pieces into the burner ports in the cooling down stages of a bisque fire. I
had a show to get ready for, 2 feet of snow in my pit and VERY had to come up with a way to smoke pots in my gas kiln in the

These are the notes from my experiment....
Bisqued to 980C
Shut off and sealed kiln to cool.
Cut/split a LOT of wood into 12" lengths and about as wide as a large HB
pencil...maybe a little wider. I intended to put it in the burner port and
as you know, there is not a lot of space there, on one side only, and as
Jack Troy suggested.
Tried wood pieces at 825C but was still too hot. Wood burned away.
Tried again, with damper open 1", at 625C...carbonized the pots but they
reoxidized again immediately. Still toooo hot. ( I know now the open
damper was the cause of this reox.)
Tried again at 475C with the damper closed. Still too hot. Wood just
burning away creating lots of smoke into the studio and if/when I reopened
the damper a 1/4 inch all the now carboned pots reoxid.
I started putting in the wood anyway from 10:30 pm to 1:30am, opening
burner port, inserting wood, closing the port and I can't get the pots to
stay carboned....just reoxid occuring. Temp reads 460C. Maybe still too
Sealed the kiln VERY tight and left it till next day.
10am ...temp reads 325C
With the damper closed, started a steady stoking again and the temp started
to rise slowly.
11:45...temp 350C, 12:20pm T. 375C, 1.:25pm T 450C....pots are carbon.
BUT at this temp the studio is filling with smoke again.
Turned on all my fans and opened the studio doors...seemed to solve the
smoke issue for a time.
1:40pm T. 500C
2PM the studio too smoky and is unbreathable (have mask on).
I (a mistake) opened the damper 1/4 inch to cut down on some of the smoke
coming into the studio, and of course reox. all the pots AGAIN. (They WERE
carboned and looking good to this point and I just should have left it
At 3pm can't get the temp to rise any higher so stopped stoking, sealed
burner port and left it.


Results..all porcelain work....
The clean porcelain work had a soft grey carbon surface.
The red TS pots were darker red but with no carbonized only areas. Not a
The orange TS pots were a bit darker is all but ok. Soft and nice.
The black TS was grey/black.

I will try this again sometime when the need arises but will do things a
bit different to get better results. Smoking studios is not a good idea and
the fire dept would not have been a great guest. ;>}}}}}.
Thank you to all those who posted me on the how-to's. An outside gas kiln
situation would be better for this kind of experiment.
I refired all the work in saggers and got it off to the show in time.
Any comments on the above will be accepted. ;>}}}}}}}}}}}}.
As Always in Clay Peggy

Peggy Heer / Heer Pottery E-Mail
Edmonton AB, Canada on sun 26 jan 97


I tried the same experiment with low fire red clay and TS and was successful
at turning the pots black on one side. Probably due to the flow of the gases
in the hot kiln. I used wet paper as my smoking device and I inserted it
into the top peep. I had a glazed deep pot to catch the paper.

Try again.

Terrance F Lazaroff
St Hubert, Quebec, Canada!!!!!