Bob Hamm on tue 10 oct 00
The discussion of knobs blowing off lids and the speed of bisque firing have
got me thinking and I would like to share my thoughts on these and other
ideas.
I agree with Tim Frederich about firing slow. I fire bisque and glaze much
slower then anyone I know. By the time my pots get to a kiln, there is
already a considerable time invested in them and I don't want to risk them
for the sake of a few hours knocked off the firing cycle. The extra energy
used in a slow firing is minimal compared to the value of the pots.
Concerning the lids, assuming an adequate technique, I think the problem of
the knobs departing the lid has more to do with moisture and impatience
during firing.
Now the two thoughts these topics have given me.
There are ways to speed up the process of making pots. If I want to dry my
pots fast then I need to understand the process of how water leaves clay. If
I know the process then I can choose a technique for drying and I will know
when to push and when to be patient. Patience at the right time allows me to
get my pots dry faster and safely. As for firing the pots, I always go very
slow until I have colour in the kiln. I also have a vent hole in the lid of
my electric kilns that is left open till I have good colour in both bisque
and glaze firings.
The second thoughts have to do with process and problem solving.
There are certain rules that I follow in the studio and two of them came to
mind while thinking of knobs and bisque firing. They may not work for you,
but maybe they are worth a thought.
The first rule is, if something bad happens in a small way, such 3 or 4 pots
cracking in a batch, don't try to figure out the cause and remedy the
problem. As often as not its a coincidence, a one time occurrence, or I just
had a bad day when I made those pots. It is likely not a real problem and
it won't happen again. Okay, I have been making pots for a long time and
have my methods worked out, so this rule works for me. If someone is new to
clay and is still developing repeatable and reliable methods then they may
want to consider it as a possible problem. If and when the problem repeats,
I research everything I have done and hit the books for relevant
information. Only after thoughtful research do I try a remedy. I learned a
long time ago that if I try to fix a problem before I understand it, that I
often not only move in the wrong direction but muddy the waters, making it
even harder to figure out the problem. I remember once trying for six weeks
to correct a glaze firing problem, only to finally discover, that I had over
time allowed my soak range move lower. One bad firing and I panicked. I
didn't think, just reacted. I tried to correct the "problem" by using a bit
lower soak range, then lower. It did not work. Then I looked at my glazes,
retesting and checking my material supplies. Did not work. A light bulb
finally went on. I looked up a firing record from the previous year and out
of desperation duplicated that firing. It worked. Lesson learned. Though
before action usually finds the short road from A to B.
The second rule is to always try the simplest techniques that you can think
of. They will often work just as well and sometimes better then the complex
approaches. I don't know what kind of lids everyone else is talking about,
but offer the following example. I have made more then 10,000 lids with
attached knobs and can only remember 1 every cracking off. I use the simple
approach. I trim the lid and without scoring, smear thin slip (sometimes
almost water) on the lid. Then I take wad of clay, roll it in my hands to a
cone shape, rock it on a shelf to round the bottom a bit. I set it on the
lid, pressing it down with a slight twisting action while slowly rotating
the wheel and then use as much water as I want to throw the knob. I don't
score, or use fancy slip, poke holes in the knob or anything else. Just set
the finished lids on a shelf an let them dry as fast as they can, sometimes
overnight. No problems. Another case was handle attachments cracking on
mugs. I tried every thing. Scoring, water, slip, a week in a damp cupboard
following by controlled drying for another two weeks. Still lost 15%. Next
batch I decided if I was going to lose them anyway might as well do it fast.
Attached the handles with slip (no scoring) and let them air dry in three
days. Lost less then 1%. I have never had losses worth thinking about since
then and have even bisqued mugs the same day I threw them without problems
using the above technique.
I use a fine grained clay body and rarely baby my work or use complex
forming techniques. These pots rarely crack , in either their bodies or
attachments, and just as rarely warp. I think understanding your materials
and gearing your processes to them is what will produce a consistent process
from clay to sales shelf. Until a good process is worked out I would rely on
patience.
I think I have rambled some. Sorry for that. I hope some of you find
something useful here and may like to respond. I would be interested in
hearing others opinions or thoughts on my thoughts.
Bob Hamm
Super Mud Works
Kelowna B.C. Canada
Phone (250) 765-8876
Email bobhamm@look.ca
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