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gas/dead air

updated sat 9 mar 02

 

Dale Neese on fri 8 mar 02


I whole heartedly agree with Mel on everyone of the safety points he =
listed about firing with gas. Never leave a kiln unattended.=20
I fire enjoyably to cone 10-11 with one of Fred Olsen's updrafts. The =
kiln is on a concrete pad outside under a high metal roof protected from =
the elements. The only little glitch is that I have had to shield the =
pilot light and burners from the swirling winds. I once had all kinds of =
baffles set up around the kiln to deflect the wind but they were blowing =
over making firing a real pain. Sometimes I could see the wind suck the =
flames in and out of the burner ports and flue. So I attached sheet =
metal "skirts" with holes around the base of the kiln. The skirts do not =
totally enclose the space around underneath. This has helped on windy =
days to keep the kiln going to red heat. I haven't noticed that great =
deal of difference in firing but sometimes I have on one or two pots =
noticed a shade of color difference in the glazes from one side of the =
pot to the other especially on the pots about midway up the setting on =
the side of the kiln that completely open, the no skirt side. Sometimes =
my copper red glazes have a spot of green on the side that faces the =
burner side that is completely open because that side has all the =
pressure control valves. I have adjusted by putting the glazes =
containing copper to other areas within the setting which has helped. I =
also place several extra kiln posts in the shelf edge at mid stack area =
to deflect the direct path of the flames on to the pots. All ten of my =
burners burn steady clean blue flame during the firing. So are these =
hotspots or cold spots that I am experiencing? Seems to me that the =
glazes are getting too hot on that one side edge before reduction, =
especially the glazes containing reds. Am I right or is there another =
cause? I have set all the shutters on the burners equally all around. =
And get good back pressure at reduction. I noticed this glaze color =
separation even before I installed the "skirts". I have seen this in =
downdrafts too, especially where the flame comes over or through the bag =
wall. Really not too many people notice the shift in color. They say =
they even like the pretty green and red "Christmas pots". And, how does =
Tom get a Geil updraft full of evenly copper red pots?? Looks like those =
kilns have a "skirt" already installed.
So what your thoughts?=20
Dale Tex