Tamsin A. Whitehead on wed 12 feb 97
After the recent thread on firing in woodstoves, I decided to give it a
go, and thought I'd just let you all know how it turned out....It worked!!
I made a few little pinch pots with my standard commercial ^6 clay -
burnished some of them a little. Dried them out and then stood them
overnight on a rack over the woodstove just to make sure they were really
dry! Inside my woodstove there is a small ledge over the firebox at the
flue entrance, and for the first part of the firing I put my pieces up
there. I stoked the fire up from a low heat to very high over a few
hours, and when the pieces looked as though they were well and truly
bisqued I made the fire up really hot with lots of coals and shoved the
pots in them. I continued firing for an hour or so (you can tell how good
the record taking was during this event - oh well, next time!), with the
damper open to keep the fire blazing. Then, when I thought they were
looking pretty well cooked, I threw a handful of dog food in a couple of
them. Then I closed the damper! Unable to resist the temptation, I kept
opening the door and peeking in over the next 30 mins or so, and I could
see where they were getting black, so I could move them around a little,
and cover them over with bark, or whatever, to get more black. After
about 40 mins (or so!) I took the pots out (all this moving of pots being
done with ordinary fireplace tongs) and placed them on top of the stove,
and then by the side of the stove. They cooled down very quickly. No
cracks or problems. They turned out very well. The colouring was uneven,
but I think that with a longer smoking time and more moving around in the
stove, I could have got them pretty black if I'd wanted to. Nice shine
over the burnished areas and lots of interesting mottling in dog food areas!
I don't know what temperature it reached, but the pots were more than
bisqued, I'm pretty sure! Hard to tell by colour, but they feel strong.
The whole event took about 6 1/2 hours and I did it last night! I was so
enchanted by the whole thing I couldn't go to bed for some time. Just
kept looking at my pots, and planning the next load!! What fun!
Tamsin
Nottingham, NH
USA
Sam Cuttell on thu 13 feb 97
I, too, have been experimenting with woodstove firings for the last few
weeks after being inspired by Clayart. I would like to make a few
comments on the below.
At 09:25 AM 2/12/97 EST, you wrote:
>----------------------------Original message----------------------------
>After the recent thread on firing in woodstoves, I decided to give it a
>go, and thought I'd just let you all know how it turned out....It worked!!
>I made a few little pinch pots with my standard commercial ^6 clay -
>burnished some of them a little. Dried them out and then stood them
>overnight on a rack over the woodstove just to make sure they were really
>dry!
I bisque fired my ^10 stoneware clay to 06 (my usual).
>Inside my woodstove there is a small ledge over the firebox at the
>flue entrance, and for the first part of the firing I put my pieces up
>there. I stoked the fire up from a low heat to very high over a few
>hours, and when the pieces looked as though they were well and truly
>bisqued I made the fire up really hot with lots of coals and shoved the
>pots in them. I continued firing for an hour or so
This is the part I feel compelled to address. We have a thermometer on
the chimney of our woodstove (available at any hardware store). Danger
zone is at around 475F and the thermometer maxes out at 900F. According
to my cone chart, 06 equals about 1800F. IMHO, there is *no* way you
were anywhere near bisque temp. Your stove simply cannot support that
kind of heat.
and I could
>see where they were getting black, so I could move them around a little,
>and cover them over with bark, or whatever, to get more black. After
>about 40 mins (or so!) I took the pots out (all this moving of pots being
>done with ordinary fireplace tongs) and placed them on top of the stove,
>and then by the side of the stove.
From my observations (we have a window on the front of our woodstove,
the black colour appears during the cooler part of the firing - I watched
a very dark pot turn almost completely white when I pushed the stove up
to 600F.
They turned out very well. The colouring was uneven,
>but I think that with a longer smoking time and more moving around in the
>stove, I could have got them pretty black if I'd wanted to.
To me, the beauty is in the mottling - I find an all black pot boring.
I tried dog food, etc. but I found the best results were achieved by
putting the bisqued pots in a relative cool firebox (around 200F) and
piling the wood around the entire pot and running the stove up to about
450-500 then closing the dampers 1/2 way and allowing the stove to cool
down slowly. When the temp is back down to 200F I remove the pots with
fireplace tongs and when cool, wash thoroughly. When completely dry,
I coat with an acrylic medium (mat) to prevent finger prints.
I showed an example at a guild meeting last night, and the result was
met with approval. I plan on entering a piece at our upcoming bi-ennial
exhibition.
Just my $0.02.
sam - alias the cat lady
Home of Manx cats, Cavalier King Charles Spaniels and the odd horse
Melbourne, Ontario, CANADA
(SW Ontario)
http://www.geocities.com/paris/3110
"Madness takes its toll. Please have exact change."
Tamsin A. Whitehead on fri 14 feb 97
On Thu, 13 Feb 1997, Sam Cuttell wrote:
> ----------------------------Original message----------------------------
> I, too, have been experimenting with woodstove firings for the last few
> weeks after being inspired by Clayart. I would like to make a few
> comments on the below.
>
>
>
> I bisque fired my ^10 stoneware clay to 06 (my usual).
>
> We have a thermometer on
> the chimney of our woodstove (available at any hardware store). Danger
> zone is at around 475F and the thermometer maxes out at 900F. According
> to my cone chart, 06 equals about 1800F. IMHO, there is *no* way you
> were anywhere near bisque temp. Your stove simply cannot support that
> kind of heat.
I am going out to buy one - good idea! I have been thinking about this
and you are probably right. As I said, I had burnished some of my pots
and they came out very nicely, and I seem to recall previous postings on
Clayart that said you lose the burnish effect if you fire to a high bisque.
(Or was that just for terra sig?) But they just FELT so solid!! And they
had developed a strong pinky/buff colour. Maybe I totally stressed the
fireplace! Yipes!
>
> To me, the beauty is in the mottling - I find an all black pot boring.
>
I agree that the mottled effect can be very beautiful, but I think that an
all black pot can be also; so many factors in the aesthetics - form,
texture, finish etc can be very effective. I saw many all black pots in
the British Museum in London last year that I thought were wonderful! Old
burial pots and so on. (Not being patronising, just my 2 cents worth!!!)
Thanks for your input on the temperature thing - much appreciated!
Tamsin
Nottingham, NH
USA
koratpot@korat.loxinfo.co.th on sun 16 feb 97
Original message
> We have a thermometer on
> the chimney of our woodstove (available at any hardware store). Danger
> zone is at around 475F and the thermometer maxes out at 900F. According
> to my cone chart, 06 equals about 1800F. IMHO, there is *no* way you
> were anywhere near bisque temp. Your stove simply cannot support that
> kind of heat.
The stack temperature of a stove doesn't tell how hot it is inside
the stove. The whole idea of a stove is to radiate the heat out into
the room before it goes up the stack. The temperature of the outside
of the stove also does not tell how hot it inside the stove, since
the job of the skin of the stove is to lose heat to the room
atmosphere.
Fire is hot. A cigarette lighter's flame will take a pyrometer probe
quickly up to 7-800 degrees C, and the flame is a lot hotter than
that, since heat is being lost in every direction.
You can bisque clay in a woodstove. At this pottery village they use
charcoal braziers to fire beads and other doodads. The beads are put
in a saggar (a little red clay pot with lid) and set on charcoal, and
then more charcoal heaped around the sides. The beads come out soft,
but good enough to sell. I played with this technique, heaping
charcoal over the lid too, and got it so hot the saggar slumped. The
beads were hard. You could do the same in a woodstove, with plenty of
air to keep the stove cool. What's important is to get the clay
surrounded by coals.
One way to guess, after the fact, how hot you have fired something is
to measure the water absorbtion. Compare the percentage of weight
increase with a sample fired to a known temperature in a kiln.
Nikom
koratpot@korat.loxinfo.co.th
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