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firing a bust

updated sat 15 nov 08


Lili Krakowski on fri 14 nov 08

I really am sorry about your bust bust. Kiln explosions are
among the dreariest of bad clay experiences, esp. that so often
the explosion ruins perfectly good "other" pots. And cleanup is
a horror.


The advice that a clay body should be "designed" for sculpture is
correct. Any place where the clay is going to be thick needs an
"open" body
that allows gases and moisture to escape without difficulty. As
you probably know from experience: when a bus is empty or only
partly full, there is enough space between passengers so you can
get off the bus without rumpling your clothes, catching your
briefcase, losing your glasses. If the bus is packed full, you
not only will rumple your clothes, but the passengers you push
aside also will be "damaged." It is pretty much the same with a
pot. The gasses "getting off the bus" need to have space, or
they cause damage.

So if you do not have a sculpture body add grog or silica sand
to the body you are using.

Then. And this is one of my obsessions,ONE CANNOT DRY CLAY TOO

You write that the bust was ten weeks in a hot room. Ok. In my
opinion it was "ruined" in the first 48 hours.

Clay dries from the outside in. It shrinks as it dries. So the
outside layer if allowed to dry quickly forms a crust through
which the moisture still INSIDE the pot, bust, clay cannot escape
without breakage. Frustrated, as it were, the gases, vapors
explode the surrounding clay

Sadly one such explosion can demolish a whole pot/bust.

My [constant] advice is: DRY THINGS SLOWLY. The thicker and
bigger the slower. Dry the pot on newspaper, and ideally, have
newspaper on a grid of some sort. I use the pallets bakeries
supply bread on to supermarkets. These break of chip and the
truck or the supermarket discards them. I "repair" as needed
with duct tape and put a thick layer of newspaper on top, and
the clay to be dried. Air circulation underneath the object
helps a lot.

Wrap the piece loosely in plastic. Just enough so that some
dampness is trapped. Leave in a cool place. Do all you can to
slow drying.

My favorite "solution", however, is the above
pallet--with-newspaper (the pallets can be cut smaller) or some
other "grid" (old wooden dish racks) laid inside a Styrofoam box,
which is closed tight. If no box is the right size, dumpster
dive for some Styrofoam (or buy a sheet of insulation foam) cut
into pieces make a cloche (duct tape again.) Put the pallet on a
piece of foam as well, have the cloche cover all.

Now. I made a largish, heavy sculpture (a bust). It was quite
uneven in thickness, though hollow most of the way. I put it in
a Styrofoam box (as above) with several damp sponges all around
it. I redampened the sponges for about a month. Then I removed
them one by one, and let the last one dry. I left the closed
box for about six months. I removed the sculpture and set it
to dry in the open. Not near heat. I keep an unfired clay tile
in the studio ( a suggestion gleaned from some book) and I know
that clay is dry. When in doubt about dryness I ALWAYS check
whether the tile feels different from the object in question. If
the tile and the object feel equally warm/cool it is ok. If the
object is even a
tidge cooler--not okay. Still damp. There are other "tests" but
this one works for me.

And if you live in the desert, no kidding, build yourself a damp

Clay will have at least 5% moisture in it, not counting the
chemical water, because 5% is the norm for air.

Lili Krakowski

Be of good courage