Neil Fallon on wed 31 mar 04
Hi folks. It has been a while since I have posted any thing here. It has
been a busy winter. I have a few firing questions. The kiln in question is
a six-month-old Olympic DD17 gas kiln. Five potters of various skill levels
all chipped in and jointly own the kiln. It has been fired successfully five
times. These have been glaze firings, cone 10, with reduction. We candle
overnight and begin to fire the next morning. The firing schedule is
roughly 9 hours. We fire using the digital kiln controller and by sighting
the cones. We rely more on the cones than the controller. Kiln is in New
Hampshire, so it has been a bit cold when we fire. Here are the questions:
(1) Excitement and anticipation causes us to open the kiln when the
digital controller reads 350. The last time we did this, we heard a lot of
"pinging" as the glazed pots cooled in the 40-degree weather. There is a
debate whether we should allow the kiln to cool so that the inside chamber
reaches the same temperature as the outside air. Is there any argument for
this, or can the kiln be opened at 350-degrees?
(2) The shino glaze I'm getting out of the kiln isn't yet perfected, but
half the challenge is trying to perfect shino. However, the shino glaze is
crackling (like some of the crackle Raku glazes.) Can this be caused by the
early opening of the kiln?
Thanks in advance for your replies.
Neil Fallon
Rock Pond Pottery
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John Jensen on thu 1 apr 04
Neil;
I read on clayart once...some one said,"If you aren't burning your hand
when you unload your kiln, you just don't care about the work."
I guess that was mostly humour and a recognition of how hard it is to
wait till the kiln is cool to unload. I usually start by just opening
the damper and the burner ports, and peeking through the peephole with a
flashlight. Not too much time goes by before I take out "just one
brick." Soon the one brick is three or four and I'm hoping the lens on
the flashlight doesn't melt as I peer in the hole. Eventually I push
the process to the point when the pots are starting to ping, at which
time I put back a few bricks and go do something else for a while.
Though I'm by no means any kind of expert in these matters, I think
pinging is not a good thing. So I try to minimize it to the extent my
impatience allows. I think crackling is going to happen eventually if
the glaze fit is not right,regardless of what you do. Probably it
happens sooner and more drastically if it happens with a shock of
temperature change.
Since I'm pretty much in a similar boat to yours, I await other
responses on this matter.
John Jensen, Mudbug Pottery
mudbug@toadhouse.com , http://www.toadhouse.com
william schran on thu 1 apr 04
Neil wrote:> There is a debate whether we should allow the kiln to
cool so that the inside chamber
reaches the same temperature as the outside air. Is there any argument for
this, or can the kiln be opened at 350-degrees?<
No debate - let the kiln cool until you can hold the pots in your
hands. Opening earlier puts greater stress on the pots, brick & kiln
furniture - simple as that.
Bill
Ron Roy on fri 2 apr 04
Hi Neil,
You don't say 350 C or 350 F
350 C is way too soon. I also think 350F is too soon - I wait till 200 F
tops - at least you can be fairly certain that any crazing that happens at
that temp would happen anyway.
I don't mean you can't crack it before then - I was taught - if paper did
not scorch in the kiln then open a couple of spy holes - maybe open a crack
to the door top.
Easier on everything if you can touch the ware at the top without burning
your hands.
I was once young though and I can remember how it was - peeking in - still
do that - but I have learned the lessons along the way - don't have to go
at top speed all the time.
RR
>Hi folks. It has been a while since I have posted any thing here. It has
>been a busy winter. I have a few firing questions. The kiln in question is
>a six-month-old Olympic DD17 gas kiln. Five potters of various skill levels
>all chipped in and jointly own the kiln. It has been fired successfully five
>times. These have been glaze firings, cone 10, with reduction. We candle
>overnight and begin to fire the next morning. The firing schedule is
>roughly 9 hours. We fire using the digital kiln controller and by sighting
>the cones. We rely more on the cones than the controller. Kiln is in New
>Hampshire, so it has been a bit cold when we fire. Here are the questions:
>(1) Excitement and anticipation causes us to open the kiln when the
>digital controller reads 350. The last time we did this, we heard a lot of
>"pinging" as the glazed pots cooled in the 40-degree weather. There is a
>debate whether we should allow the kiln to cool so that the inside chamber
>reaches the same temperature as the outside air. Is there any argument for
>this, or can the kiln be opened at 350-degrees?
>(2) The shino glaze I'm getting out of the kiln isn't yet perfected, but
>half the challenge is trying to perfect shino. However, the shino glaze is
>crackling (like some of the crackle Raku glazes.) Can this be caused by the
>early opening of the kiln?
>Thanks in advance for your replies.
>Neil Fallon
>Rock Pond Pottery
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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