Deborah Thuman on sun 2 oct 11
I fired to about ^05 yesterday, then closed the damper and put the
plugs into the peep holes. Jim called a little while ago telling me he
opened the damper and pulled the plugs. Lots of very hot air is
escaping the kiln. I finished firing at 3:15 pm, and he opened the
damper about 8:00 am. Hmmmmmm........ interesting. The kiln is taking
about as long to cool as if I had fired to ^5. I had wondered for a
bit if I had turned off the kiln. Yes... I know I did. It's my habit
when shutting off the kiln to first turn off the main gas valve. It
takes a few seconds to burn out any gas in the lines and then I turn
each handle (ring, inner burners and outer burners) off and shut off
the valve for the pilot light. The kiln was about 2/3 full, so I'm
wondering why it's taking so long to cool.
Jim made cone packs for me - his first time making them. I seem to
have left a bit out of the instructions because he didn't push the
cones down far enough. They fell over without melting. Ok...... Looks
like ^08 is down so I start reduction. I had to wait for the edges of
^05 to start to soften to figure it was time to turn the gas down very
low (inner burners off, outer burners 1/4 or less open), open the
damper all the way and soak for 15 minutes. My usual soak is 30
minutes, but I wanted to try a shorter soak. One of the grad students
fires low fire clay in the electric kilns and programs a 5 minute soak.
As I was starting the firing, Jim told me he read in Vince's book that
when you once fire, it's important how you ramp the kiln. Oh, boy. Jim
had an unbisqued piece in the kiln. The kiln is at NMSU, Vince's book
was at home. Ok... rather than increasing the gas every 1/2 hour until
read heat, I'll increase every 1 hour. Firing took 4 hours 45 minutes.
A pyrometer would have been helpful, but the clay studio doesn't own
one. That's because all firing is done in electric kilns (computer
controlled) or in the Blauuw. There are all of two students who use
the fully manual gas kilns. The other student makes large sculptures
that would be a royal bear to put into and pull out of a top loading
kiln. It was suggested to me that I buy my own pyrometer, have it
hooked up to one of the fully manual kilns.... Um.... there's this
little problem of my pyrometer growing feet or being abused by other
students. Yes, I could take part of the pyrometer home with me - I'd
have to leave the other part stuck into the kiln. I still don't like
the idea.
Because there are only two students who use the fully manual gas
kilns, the oldest and cruddiest shelves are reserved for those kilns.
When we have our own kiln, I will buy advancer shelves. Why? Because
at my age, a prophylactic is taking a muscle relaxer after loading the
kiln so I can get out of bed the next morning. I want lighter shelves.
I'll buy kiln furniture rather than using bricks. Same reason, lighter
and easier to handle. I also had a hard time finding 6 shelves that
weren't cracked. Note to self: ask my teacher about using the advancer
shelves that are reserved for the blauuw.
Things to think about for next firing:
1. Teach Jim how to build a cone pack
2. Get a digital pyrometer (I can't read the analog ones - my eyes got
too old)
3. Read Vince's book about once firing.
4. Hold the experiments to a minimum with each firing. I had way too
much experimentation going on in this firing. Jim had a once fire
piece, a piece that he was doing another glaze firing for, and the
once fired piece had a copper carb wash without any glaze. I had two
pieces with copper carb wash and glaze over the top.
5. Jim wants to put a couple test tiles with raku glaze in them on the
next low fire reduction firing. He's thinking there may be a way to
make smokeless raku. Jim loves raku, but he's allergic to smoke. Who
knows?
Deb Thuman
http://debthumansblog.blogspot.com/
http://www.etsy.com/shop.php?user_id=3D5888059
http://www.facebook.com/pages/Deb-Thumans-Art-Page/167529715986
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