John Baymore on sun 31 may 98
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I found an old article in CM from sometime around 1989 or
so that dealt with getting similar effects (of low-temp saggar or
pit firing) in a regular gas kiln, firing to cone 8, using
charcoal and soluble salts such as copper sulphate, and without
the use of a saggar of any kind. I don't remember the exact issue
- anyone?
(snip)
If you do that copper thing without a containment of some kind.... you
probably will make the kiln a permanant copper fuming unit =3Cg=3E.
You can fire pieces in contained saggers with combustabiles at most any
temperature.
You can saggar fire pieces up to at least cone 10 with things like sawdust,
wood chips, charcoal, salt, chicken bones, egg shells, sea shells,
vegatable type- compost garbage, + add copper to taste. Some similar
qualities to low temp saggar work...... particularly if you tightly pack
the sawdust so that it never burns away completly .... but mostly effects
similar to the effects gotten in the firebox area of wood kilns.
The same clay bodies that are good for salt and wood firing are best for
this stuff.
If you do this, make sure the kiln is well sealed and also well ventilated
........and the kiln room is too. I mean REALLY well ventilated. This
technique produces LOTS of noxious stuff that you DON'T want to end up
breathing. This is a NASTY technique........ lots of fumes. At certain
points in the early firing you get smoke and stink coming off the kiln
stack. (That is pretty much true of the lower temp saggar firings too.)
Don't put too much salt into a saggar..... a little goes a long way.
High fire saggars need to be durable and strong. Otherwise they will
deteriorate quickly. Best to use a sagger formulation fired on a cycle for
making refractories not pots.... and they MUST be pre-fired before using if
you want them to last at all.
Place the piece on a cookie of clay made of the typical mix for wood kiln
separater wadding in the bottom of the saggar..... on top of a layer (1/2
inch) of dry kaolin. Helps make sure you get the piece out of the saggar
in one piece..... and keeps the saggar floor from getting too badly gunked
up.
I used to teach a class that included this high temperature saggar
technique back in the early 80's at Massart in Boston titled =22Fire Painted
Clay=22. The course also included very controlled raku techniques, pit
firing, salt/soda, and wood firing.
Best,
..........................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752
JBaymore=40Compuserve.com
Jennifer M. Dubats on tue 2 jun 98
John ,
If the Saggar is tightly sealed with clay (or possibly kaowool ? ) is it safe
to fire in an electric kiln? Or should I avoid salts if I use the electric
kiln and just use copper wire and other combustibles? I did hear that you
could fire sawdust in a saggar in the electric kiln ( with a pot of course) if
you alternate these firings with bisque firings but would like to have that
confirmed.
Sincerely,
Jenny D., whose reduction kiln is still a pile of brick out back...
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