Hendrix, Taylor J. on tue 13 may 03
Howdy all:
Well, today we fired up our raku kiln again. We got two loads done and
I was only one and a half hours late to work. Thank god for student
workers.
Some nice color on our cu glaze, but the crackle white was under fired.
My test pieces didn't break (one cracked) which is interesting because
the clay body was a grogged ^5 clay.
Yes if you must ask. I did singe my eyebrows and eyelashes. My bangs
have now inched up a bit on my forehead and...who the hell is that
smoking?!
I am going to put all the vital stats below and ask for some advice.
The first firing took two hours from cold to in the cans. The second
firing was one hour twenty-eight minutes to the cans. I think this is a
bit slow at least for the second firing. I will try and anticipate the
questions, but does anyone think they see a possible cause for the slow
firing and the solution?
Kiln: a converted electric HIGHFIRE from paragon. Inside dimensions
are 1.5"x17.5"x27.5". The lid is two layers of kaowool.
Burner: Weed burner rated at 500,000 btu. (hoping that's not Bahaman
thermal units!) Flame tube is 2" wide. =20
Burner port: 5.5" x 4" (This may be a bit large for our burner head)
Flu: 5.75" diameter circle (I do have a piece of kaowool for a damper)
Here are the notes of the two firings--
Firing one 5/13/03:
12:50 start at 1 psi. Burner 1/2 in port, needle valve full open (never
touched it again)
1:04 psi up to 2. Brought burner out, 1" from burner opening.
1:18 psi up to 5.
1:38 psi to 6
1:52 psi to 8. Taylor is getting a bit bored and wants to throw
insects into the flu hole.
2:21 psi to 9 Still no melt while looking into the kiln. This might
be were I first started to singe my face.
2:27 psi to 11! Can't stand it. Floor bricks are red and parts of
exposed elements are red.
2:38 psi to 12 Edge of white crackle glaze going wet.
2:50 burner to soft yellow. Pots in reduction cans. Cool, smoke.
Pots--cu looks good(typical raku cu) white crackle under fired on
portions of pots. Good black carbon from newspapers.
Firing 2 5/13/03: (Barb left lid off kiln and let it cool down for about
5-8 minutes. Man, bummer. She was worried about harming the cool
bisque)
3:00 2 psi
3:08 5 psi
3:15 7 psi
3:23 9 psi
3:36 12 psi! Taylor is frustrated and takes a chance with Barbs pots.
His were fired first.
3:44 no melt
4:10 closed half the flu with kaowool piece. Thought this might help.
4:30 white crackle melting well.
4:35 in the cans
Pots--cu good colors again. White crackle okay with minimal crackle.
Some of you have suggested to me that 4-5 psi is adequate but at 12 I
saw almost no yellow flame. I'm all for cranking up the psi as soon as
possible. We might be having too much heat escaped out the flu at the
top, but how else will I be able to burn my face off? I really couldn't
tell for sure if dampening off the flu on the second firing helped get
it to temp faster. Didn't have a kiln god ready for the first firing,
but Willie was sittin above the flu hole on the second one.
Thanks everyone who answered my off list and on list questions up to
now.
Gawd, can you imagine what would have happened to me to day if I still
had my ponytail????????
Taylor, in Waco
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