Lily Krakowski on thu 10 oct 02
Sweet are the uses of insomnia. I have been lying here trying to visualize
a twelve by twelve by twelve lump of solid clay to be fired.
Of course all that Snail wrote is true, but I do not share Snail's tentative
optimism.
For newbies.
Clay dries on the outside first. Just as a loaf of bread does. No news
there. But as it dries it shrinks, and the outside, drying quicker shrinks
"shut" . One of the reasons for using different mesh sizes of clay and
other materials and adding grog or sand is to keep these "pores" to the
outside open so that not only mechanical water--that used in mixing the
clay-- can escape in the drying, but so that gases, including chemical
water--that which is the H20 in the molecules of clay and other materials
can escape in the firing.
This person --sorry, misplaced the name--wants to fire a solid piece of clay
that approximates 4 clay packages --the long 6"x6" ones-- as a unit.
Snail suggested a long long careful candling. I still cannot imagine that
there won't be some water left inside there, and whooooom. Massive
explosion which can damage elements and kiln wall.
If the piece is still leather hard I would try sawing it in two at least,
using an old, non-electric wood saw. With fine teeth. Rewet the cut as you
go. Once it is cut up, you can try hollowing it out. You will have to
create a tool akin to a melon baller, except don't use a melon baller
because they are chinzy and fragile and I still have the scar from when one
broke when I was trying to use it on a potato.
If it is beyond leather hard, I would put it in a picnic cooler that seals
well and leave it in a warm place--room temp--over several MONTHS. Peek
inside every few days, and if there is any water accumulating at the bottom
mop it up.
To the late Dutchess of Windsor's dictum one cannot be too thin nor too
rich, I add nor dry clay too slowly.
And then I would take it out of the cooler and just wrap it in plastic and
let it sit in a warm place.
Then and only then would I try to fire it.
And yes, I'd still be prepared for the whoooom.
Truth to tell if I had this block and it were not heavily grogged clay, I
would seriously think of making a mold of it, and then redoing it hollow
from the mold.
And remember my favorite home made proverb: God loves a cheerful quitter.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Snail Scott on thu 10 oct 02
Gotta agree with Lili Krakowski on this one.
I hope I didn't sound too encouraging in my previous
post. The firing that I discussed was for the 5" piece
that I did, and volume increases as a CUBE. Jun Kaneko
did a famous set of 'dangos' which were 13 feet tall,
but even they were only about 9" thick, and he took
a MONTH to do the firing. That's not time spent loading
the kiln, or waiting for stuff to dry. The actual 'fire
in the kiln' phase took three weeks of continuous, VERY
slow firing. And your piece is smaller but thicker.
I assumed, as I said, that you had a good reason for
wanting them to be solid, but you need to be very, very
sure of that. Is is that they were made solid? As Lili
pointed out, it's never too late to cut something apart
and hollow it out. For a piece small enough to fit into
a standard top-loading kiln, just a few needle-tool
holes are sufficient to vent the interior air volume of
a hollow piece. If it's just a foot in all dimensions,
one little hole will do it.
If it needs to be solid for weight, maybe you could fill
it afterward with concrete - other people have used this
method for work which needs solidity or mass. If it needs
to be solid for conceptual-art reasons, then perhaps
you need to look at your concept. You are asking your
material to do something nearly antithetical to its
nature. It that really an integral aspect of your idea?
It is a common tendency among people who are skilled in
one particular medium to choose that medium for all their
ideas. However, just because it's 'your' medium doesn't
make it the best choice for every project. Does this piece
really need to be clay? There is a growing legitimacy,
especially within contemporary art circles, to regard
cast concrete as a legitimate art medium. Concrete, unlike
clay, lends itself well to solid forms, and can be tinted
and modified in many interesting ways. Cast resin is
also a medium with many versatile properties.
It may be possible to fire your solid piece, but be aware
of the LONG process ahead of you, and be very sure it's
really what you want.
-Snail
Bruce Girrell on thu 10 oct 02
Everything that Lily said.
And also, should it happen that you manage to get your block of clay heated
to above 100 ºC without the explosion, please remember that dehydroxylation
of the clay, which occurs in the neighborhood of 575 ºC, also results in
significant gas generation. Normally I don't consider LOI to produce
significant gas, but with the size of block that you're talking about you
may need to consider the breakdown of organics as well.
At any temperature where significant gas is released you will need to
_creep_ through the temperature range. If I were trying this, I would first
dry the thing slowly over months, then spend a few days to a week or so near
100 ºC, then start up slowly over the next day or two to get to 500 ºC. At
that point I would go as slowly as possible, again three days to a week, to
get up to 600 degrees. Once you get past the dehydroxylation point, you can
probably finish pretty quickly - perhaps another day to hit whatever cone
you are aiming for.
Bruce "a real creep" Girrell
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