Merrie Boerner on thu 3 may 01
Hi Matt,
You asked, "What cone did you fire to?"
cone 13 in front, 12 in the middle and 12 bending in the back.
"How long was the firing?"...This time is was 43 hours.
"What sort of wood did you use? Was it really dry wood or fairly fresh?
How much wood would you
guess it took to fire the kiln? " We used about 4 to 5 cords. There wa=
s a
whole trunk of a green pine tree and a trunk of a very dry pine tree, and
about 2 cords of pretty dry oak.....all with bark and chopped. We also ha=
d
some old flooring 2X4s and odds and ends. Then we finished off with a
trailer full of carpenter scraps that are about 1" diameter and 4'
long.....stoking them for about 3 hours.
I have "crusty " ash sometimes in places, and I agree with you that i=
t
is not pleasant on the lips....you must melt it at cone 11 or above. I ha=
ve
seen beautiful work fired in fast fired kilns.....the effect is just
different from what I am looking for. I'm not really leaning toward
functional, but there are places in my kiln where I can put mugs and
casseroles and hope for the best.
My kiln is about 110 cubic feet of pot space with a large fire box an=
d
tall chimney. We use to fire for 24 hours and got some ash....but we wan=
ted
more...so, we stoke wood with bark and longer. We always got to cone 13 i=
n
the front, but I think you need time, at least cone 11, bark, and just do=
n't
be in a hurry to get to temp and shut her down. Fool around with the ashe=
s
some and watch them fly....enjoy every minute.
I'll be glad to write to you personally about firing.... just e-mail =
me
at Boerner@tislink.com
My kiln was also featured in Ceramics Monthly in June 2000 issue...yo=
u
can see the building in progress and the inside of the kiln. Also, if y=
ou
go to the archives, search my e-mail address, you will find many rambling=
s
about my firings and fun stuff.
Enjoy,
Merrie in Mississippi
Matt MacIntire on fri 4 may 01
OK I get it now...
Longer firing, higher temperature, more moisture in the wood, all these
would tend to yield much more ash buildup.
The kiln where I am firing is not my own. But wood firing is the most
interesting firing I have ever done. The effects in this kiln seem (to m=
e)
rather in-between a gas firing and what I imagine when I think of a wood
kiln. We get lots of flashing of course, but little ash build up. Now I
know why.
Like you, I find that I drift away from functional pieces like mugs and
bowls and lean towards larger jars with big surfaces where the fire can
leave it's mark. The last couple firings I've been trying to encourage t=
hat
ash accumulation by putting some ash directly on the pots. This "cheatin=
g"
seems to work fairly well but lacks the full effect of a natural ash glaz=
e
coating. It'll do for now. I probably ought to catch the shino wave, si=
nce
the shino glazes seem to come out great in this kiln.
one more question if I may
(this may be of interest to the group)
How on earth do you get to cone 13?
We use a pyrometer to monitor how the temperature is changing, but (of
course) we use cones to determine the firing's real progress. I find tha=
t
it is quite difficult for us to advance that last 100 degrees F to get co=
ne
10 down.
It seems easy to get to cone 7 or so with our little wood kiln, but it is
very tricky to manage the kiln to advance that last bit. It takes severa=
l
hours to get the last couple cones down.
I wonder if something about the kiln design is limiting us. The firebox
grate area seems quite large in comparison to the kiln space. I'd estima=
te
the grate size as about, say, 16" X 42". But the airspace seems tight to
me. The opening for air is only about 150-200 square inches (1 - 1.4 sq
ft.) this is about equal to the cross section of the chimney.
One thing I have always found curious about this kiln is that there
typically is a lot of unburnt fuel in the chimney. I estimate the chimne=
y
is about 14 feet tall. Often during firing, flames shoot out of the chim=
ney
several feet into the air. If this were a gas kiln with blowers, I'd
increase the air to shorten the flame. This is not my kiln, and I haven'=
t
yet convinced them to try a more oxidizing flame as the firing progresses=
=2E
As it fires now, the kiln is in light reduction most of the firing. As t=
he
wood burns off and it is time to stoke, then it approaches oxidizing
conditions.
Does your kiln have giant flames leaping out the chimney? How big is the
air supply compared to the grate space? I wish I could see your kiln in
action, but Mississippi is a long way from Maryland.
Thanks for answering my long messages. I appreciate your comments. I wi=
ll
take your advice and search the archives for your musings.
Matt
Tommy Humphries on fri 4 may 01
If I remember right, I saw an old diagram of a single shot groundhog kiln
once that had, on either side just behind the firebox some brick boxes
vented into the ware chamber where ash was placed and during firing these
ashes were raked and stirred up the pull from the kiln sucking the ash in=
to
the ware chamber to add extra ash deposits.
might have been in foxfire 8, or in raised in clay...can't remember right
now
Tommy
----- Original Message -----
From: "Matt MacIntire"
To:
Sent: Friday, May 04, 2001 12:13 AM
Subject: Re: Woodfire#12 Hog Chain POTS
> OK I get it now...
>
> Like you, I find that I drift away from functional pieces like mugs and
> bowls and lean towards larger jars with big surfaces where the fire can
> leave it's mark. The last couple firings I've been trying to encourage
that
> ash accumulation by putting some ash directly on the pots. This
"cheating"
> seems to work fairly well but lacks the full effect of a natural ash gl=
aze
> coating. It'll do for now. I probably ought to catch the shino wave,
since
> the shino glazes seem to come out great in this kiln.
>
>
> Matt
>
>
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