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wow, conner burns (single firing)

updated thu 28 sep 06


Snail Scott on wed 27 sep 06

On Sep 27, 2006, at 2:27 AM, curtis adkins wrote:
> I just would like to throw a question out to the lot of you. What is
> everyones spin on single firing of stoneware pots and/or
> sculptures?...I guess what I am asking is is there any way to do this
> without using the spray technique?

I do most of my work single-fired, especially the
larger sculpture. The economics of only paying
once for fuel are augmented by reduced wear on
the equipment, only having to sit up babysitting
the firing once, and only having to load and
unload an awkward piece of work once. I got into
the practice in college, where getting kiln time
was practically a blood sport, but I continued it
in my own studio for several other reasons.

My forms seldom lend themselves to spraying
(too many 'shadow' areas and undercuts), and
if I don't spray, I can work in my studio without
needing a spray booth or needing to haul the
piece outdoors. I generally brush all my glazes,
and since my work tends to be thick, I don't worry
about destroying the piece with water absorption
from glazing.

Dipping may be an option if your work is small,
and pouring may be useful for work with regular
convex contours, and for interior cavities.

How a glaze (or engobe or slip) can be applied
with a brush has a lot to do with the clay. Some
clays just seem to disintegrate when re-moistened,
and thin-walled work is especially vulnerable. If
this is the case, try to do your glazing while the
clay is stiff leather-hard. Very little absorption will
occur at this stage, and the work will be at its most
durable. Of course, this means you can't rely on
the absorption of the clay to help build up a thick
layer of glaze. (This is one issue that spray-
glazing can sidestep, since subsequent
applications won't wipe off the underlayer, as can
happen with multiple brushed coats.) However, I
find that adding CMC to the glaze will facilitate
applying second or third brushed coats.

Some glazes dislike being applied to greenware,
but I seldom feel restricted in having to choose
from among greenware-compatible formulas. If
you have a 'line' which requires you to stick with
a particular glaze, though, this may be an issue
for you. If you need to keep your glaze the same,
and it doesn't like green application, it may not
be worthwhile to change your process. Or maybe
it is? Might be just the time for a new glaze palette.

There are some occasions when I do choose to
multiple firings. For instance, I do bisque work
which is made in sections which can't be test-fitted
until after firing. Once bisqued, the parts are sturdy
enough to handle, but soft enough that the fit
between sections can be trued up with a masonry
grinder much more easily that if the clay were
fully vitrified. I also might bisque if I am working in
a series requiring a consistent surface from one
piece to the next. If I glazed each piece at completion
and then started building the next, I'd be unlikely to
get just the same application of the surface effects.
I don't have the space to have a lot of greenware
sitting around safely, and if I bisque it, I can store
it with less fear of breakage while I finish the rest
of the series. Oxide wipes are also different when
done on bisque rather than on green clay, and
some work is just too delicate to sustain the close
handling of the glaze process unless it's sintered

I also do multiple firings in which the first firing is
to full vitrification, and subsequent firings are lower.
I have some work which was fired four times, none
of which was a bisque firing. This allows me to
use lower-fire glazes together with higher ones,
working my way back down the temperature scale
for each new surface element: Stoneware glaze
firing, then low-fire glaze firing, then (maybe)
another low-fire layer to tweak the first application,
then some china paint, some overglaze lusters,
etc.; you get the idea. It's true that multiple firings
do use more fuel (and time and energy and cash),
but if I've got a month of effort in a single piece of
sculpture, It's worthwhile to get it right. Using fewer
firings just to pinch pennies is pound-foolish if the
work really needs something else.

There are a lot of rewarding possibilities that aren't
tied to the whole 'bisque it first , then glaze it once,
and live with what the kiln gives you' mentality.
Nothing wrong with it, if it suits your intentions, but
it's not holy writ. Apply some considered thought
to the reasons for your process, then choose.