William Hershey on sat 28 jun 03
Looking for firing advice from anyone wth this kiln. Had to give up on my initial firing cone
10 firing after 7+ hours because I couldn't even get 06 to budge.
Here's the specifics:
Gas line: 1" (natural gas)
Bottom Shelf: 3" (per manual)
Loading: 2 large (18" tall) pieces on bottom shelf
Air Plates: Almost closed (1/4") on the burner closest to the line, and the one directly across
from it (the flame kept blowing itself out otherwise) About 3/4" open on the other two.
Manual says to open more if firing slow.... they were all open as much as possible - any more
and they were sputtering on and off.
I'm new to the firing end of things, so any advice would be great. Also, if anyone can tell me
how long I can expect it will take for a cone 10 firing.
Thanks
Eric B on sat 28 jun 03
look to how long the gas line is and how many bends (90 degrees) there are in
the line. both of those factors reduce pressure.
also, since you are using natural gas, are you sure the orifice in your
burners are set for natural gas and not propane? propane is a hotter burning gas
and therefore the burners -- if they were engineered for it -- will have
smaller orifices.
there are many other factors, such as ambient temperature and wind, but at
this time of year i'm assuming those are not affecting your firing.
Michael Wendt on sun 29 jun 03
William,
Make some flame spreaders that act as hot face igniters to the flame so it
can't blow out.
Here's how:
Get some kaolin, some alumina, some dish soap (I used Palmolive) and a roll
of cheap toilet paper. In a 1 gallon container, place 1 lb of kaolin, 1 lb
of alumina , 1 cup of water and 1/2 cup of dish soap. use a small fast paint
stirrer on an electric drill to mix the ingredients to a slurry and entrain
lots of air. If the mix is too dry, add a few ounces of water at a time to
make it frothy. Adding a few squares of toilet paper at a time allows you to
make the foam more stable. Some people add scraps of kaowool to the foam if
they have them.
Pour the foam out on a sheet of newspaper lying on a piece of sheetrock. The
top thickness can be set by the use of a second layer of newspaper laid over
the first and supported by 1/2" thick sticks. Place a second piece of
sheetrock on top and it will squeeze the foam to a uniform thickness.
When dry, fire to cone 10 or hotter, then cut into pieces to extend part way
into the flame stream over each burner port (see below). They will touch the
underside of the bottom shelf.
* *
* *
* * this protrusion is moved into or out of the flame front to
control flame spread and also gets red
* * hot within seconds so even if the flame jumps off the end
of the burner tip, it stays lit.
* *
Call me if this is unclear. These kilns run very fast and can be made to
fire fairly evenly. I have made mine 40" tall and we still hit cone 10 from
red heat in 3 1/5 to 5 hours depending on load density.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Avenue
Lewiston, Idaho 83501
1-208-746-3724
wendtpottery.com
William wrote:
Looking for firing advice from anyone with this kiln. Had to give up on my
initial firing cone
10 firing after 7+ hours because I couldn't even get 06 to budge.
Here's the specifics:
Gas line: 1" (natural gas)
Bottom Shelf: 3" (per manual)
Loading: 2 large (18" tall) pieces on bottom shelf
Air Plates: Almost closed (1/4") on the burner closest to the line, and the
one directly across
from it (the flame kept blowing itself out otherwise) About 3/4" open on the
other two.
Manual says to open more if firing slow.... they were all open as much as
possible - any more
and they were sputtering on and off.
I'm new to the firing end of things, so any advice would be great. Also, if
anyone can tell me
how long I can expect it will take for a cone 10 firing.
Thanks
Paul Vernier on sun 29 jun 03
Two things.
First, How much pressure are you getting through your gas lines. Make sure
there is sufficient pressure and flow.
Second, given that you are firing taller pieces. It is likely you do not
have a baffle shelf located an inch and a half below the lid. Gets a bit
tough to do with short posts. You need to have a baffle shelf to deflect
the burning gas and heat back down into the kiln. This slows the gas
departure and increases temperature. With the damper and baffle you can
better control temperature. Likely you were heating the outside of the kiln
as much as the inside :~)
I have been firing a tourchbearer for about 3 years. It will reach cone 10
generally faster that you should. So I believe the problems lies in one of
the two areas mentioned above.
I would strongly recommend a dual probe pyrometer as these kilns are
notorious for firing uneven top to bottom. With the dual probes you can
quickly work through this problem.
Paul
in Santa Cruz
Looking for firing advice from anyone wth this kiln. Had to give up on my
initial firing cone 10 firing after 7+ hours because I couldn't even get 06
to budge. Here's the specifics: Gas line: 1" (natural gas) Bottom Shelf: 3"
(per manual) Loading: 2 large (18" tall) pieces on bottom shelf Air Plates:
Almost closed (1/4") on the burner closest to the line, and the one
directly across from it (the flame kept blowing itself out otherwise) About
3/4" open on the other two. Manual says to open more if firing slow....
they were all open as much as possible - any more and they were sputtering
on and off. I'm new to the firing end of things, so any advice would be
great. Also, if anyone can tell me how long I can expect it will take for a
cone 10 firing. Thanks
Donald Burroughs on mon 30 jun 03
Hi William
I have an AIM gas kiln which is much the same configuration as your Oly
torchbearer. I would also suggest as was posted by Eric B that you check
your orifices and make sure they are natural gas and not propane. Your
manual if you have one should have at least a paragraph on the subject.
I myself use propane- less hassle and less expense than a NG hookup, plus
I'm guessing that your local NG supplier hasn't a clue as to your needs. If
you have not made too much of an investment I would go propane. My kiln can
fire to cone ten on good day- very little wind according to the manual on
two BBQ tandemed tanks. I usually fire to cone 6 with no problems.You can
now purchase a propane tank the size of two small ones at Wal-Mart.
Sincerely, Donald Burroughs
On the web @ http://www.autobahn.mb.ca/~donaldo
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