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chronicle of a gas kiln, part iii

updated wed 12 jun 02

 

Stephani Stephenson on tue 11 jun 02


Julie
If you've had problems with pots exploding, I can't imagine why your
analysis would be to "fire faster in the beginning"
If anything t sounds like you are going TOO fast in the beginning.
It sounds to me like you have too many unknown variables in your
process.
I don't know your work or experience level, but your post might suggest
a few things:

1. Glazes. You are working with a variety of glazes which you have
little experience with. You need to test your glazes, with YOUR, clay,
YOUR mixing method, YOUR application method, YOUR firing method. This
takes TIME!!! Do some test tiles of each glaze and place them in
different parts of the kiln.

2. take a look at your mixing, measuring, and application methods...are
you methodical, consistent, accurate?

3. I wouldn't worry about 'firing down' at this stage, you still have to
work out the bugs in 'firing up'. It sounds like firing is still a bit
on the wild side.

4. Figure out why you aren't seeing cones after 1900 degrees. is the
atmosphere too cloudy or is it something about cone placement? if it is
the atmosphere, are you reducing too heavily for too long? have you
tried placing cone packs in different areas in the kiln? Do you know if
uneven firing contributes to the differences in glaze response?

5. You have got to be a detective here and examine everything, but in
order to do that you need to reduce your variables a bit and come up
with a few constant factors.
.
6. I would say the first variable to get control of is the blowing up
of pots. Pay attention to early part of firing . do not rush it through
the first 400 degrees. pay attention to how fast you take the kiln
through quartz inversion temp. Are you seeing any black core in a
broken cross section of clay? have you had any bloating? these indicate
too much reduction early on and , among other things, firing too fast
in the early part of the firing, respectively.

7. on splitting and cracking, did the form of the pot have anything to
do with it? a wide diameter bowl with a thin rim, etc.? can you tell if
the pieces split on firing ?(glaze still melted on edges of crack) or
cooling? (edges are sharp, glaze not melted on edges)

8. So there are no easy answers. The clay you use is a factor, the way
you form your pots, the way you mix and apply glaze, the way you load
the kiln, the way you fire the kiln, and the way you analyze what
happened. This will come together after MANY firings.

SO take heart . Not all of us are methodical and analytical from the get
go. Some of us like to throw everything but the kitchen sink, and in
fact including the kitchen sink into the kiln each time. Some take a
narrow focused path, others cut a wide swath!
Some of our studios resemble clinical, pristine workspaces, other's
studios resemble the mad Dr. Frankenstein's lab! But over TIME we we
all learn what works!

cheers
Stephani Stephenson
Carlsbad CA
steph@alchemiestudio.com