Ben on thu 11 nov 04
A while back I sent some questions about a 3ft. gas electric conversion =
I was having trouble with. First time firing gas. Recently I had a =
sudden round of blistering. After 20 firings I'm starting to get it. I =
appreciate those on and off list who had suggestions. I fired this kiln =
because I had it (for the price of a burner) and I wanted to understand =
it before I fire our larger kiln. As many of you know the problems are =
concentrated in a fuel kiln this size. I'm amazed at the subtlety and =
complexity of the relationship between gas pressure, orifice size, flame =
length, draft, atmosphere and heat distribution as well as the timing =
requirements of the clay and glazes themselves. You never touch that in =
an electric kiln. You might never touch it in a well designed gas kiln. =
(I can't wait to fire wood.) I'll be glad when I have a decent kiln and =
a (semi)consistent firing schedule... but the understanding ... the =
struggle ... if you deliver the butterfly from it's chrysalis it won't =
gain the strength it needs to fly.
Two burners in a spiral seems to work the best. Have to aim them and =
adjust the primary down to lengthen the flame to fire evenly.=20
The blistering was in the firing. Joe Koons got right on me about three =
hours between 1000 and 1400. ( is 1260 to 1625 better?). But I also had =
to use a smaller orifice in that range to get better primary air (cheap =
burner, small kiln, long reducing flame.) =20
=20
(At www.reil1.net/BTU_Calculator.xls there is a very helpful tool for =
calculating btu capacity (heat rise) at different orifice sizes (flame =
length and quality) Just hit cancel when it asks for a user and it loads =
right up.
I'll be off list for a while after next week. We're going up to =
Ashland, Ore. to look for a place. I put up a few pictures from our =
recent kilns if any of you are interested. www.thecommonpot.com=20
Mostly wanted to say thanks 'fore i'm off list a while,
Ben
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