dalecochoy on wed 28 feb 07
Today I am doing something that I rarely have to do.
I am bisqueing in my gas kiln. Usually I bisque everything in my electric
kiln, all clays, whether they will be fired to cones6-7 in electric or cone
10 in gas kiln. I have to use the gas kiln when I have a pot just too big to
fit in the electric kiln, so, I load the gas kiln all up with everything I
can get in and bisque fire it to cone 04 (about 1920 degrees)..
Today I was wondering, does anyone who bisque fires in gas ever do reduction
firing towards end of bisque? If so, do you find it really makes any
difference in body colors when they are then high fired? I always do a body
reduction while high firing in the gas kiln but just wondered if it
accomplished anything if done during bisque, ESPECIALLY on clays that I will
be later firing to cone6-7 IN THE ELECTRIC KILN instead of the gas kiln.
Anyone?
Regards,
Dale
Lee Love on thu 1 mar 07
My kiln naturally goes into reduction at about 012, my end bisque point.
No, it doesn't seem to have any effect on the glaze firing
and the clay body.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
Lee Love on thu 1 mar 07
For new folks, I should add: I only have a wood fired kiln. I
bisque in it and high fire in it.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
Gail Dapogny on thu 1 mar 07
Hi Dale,
We always bisque in a gas kiln (holds more, easier to load), but we
take great pains not to reduce in the bisque and to bisque-fire
fairly slowly.. Want to burn everything possible off. Don't know
about reducing the body when you'll be high-firing in electric.
Gail Dapogny in Ann Arbor
On Feb 28, 2007, at 7:56 PM, dalecochoy wrote:
> Today I am doing something that I rarely have to do.
> I am bisqueing in my gas kiln. Usually I bisque everything in my
> electric
> kiln, all clays, whether they will be fired to cones6-7 in electric
> or cone
> 10 in gas kiln. I have to use the gas kiln when I have a pot just
> too big to
> fit in the electric kiln, so, I load the gas kiln all up with
> everything I
> can get in and bisque fire it to cone 04 (about 1920 degrees)..
> Today I was wondering, does anyone who bisque fires in gas ever do
> reduction
> firing towards end of bisque? If so, do you find it really makes any
> difference in body colors when they are then high fired? I always
> do a body
> reduction while high firing in the gas kiln but just wondered if it
> accomplished anything if done during bisque, ESPECIALLY on clays
> that I will
> be later firing to cone6-7 IN THE ELECTRIC KILN instead of the gas
> kiln.
> Anyone?
>
> Regards,
> Dale
>
dalecochoy on thu 1 mar 07
Thanks Ron and Chris Trabka,
I'll be sure NOT to do it then as many of the clays I use, for darker pots,
are very iron or impurity bearing.
I sometimes have had bloating with very dark clays in regular oxidation
electric high firing so I'll be sure not to get into that w/gas bisque that
I do sometimes. It's faster for me anyway without trying to reduce in my
Olympic updraft when doing bisque..
Thanks for the answer guys.
Dale
Dale,
I have only one kiln, a gas fired MFT. In my bisque fire I always ensure
that the firing is always oxidation. Reducing during a bisque can lead to
black coring and bloating. John Britt in his new book "The Complete Guide
to High Fired Glazes" has a good discussion on bisque firing.
Chris
----- Original Message -----
From: "Ron Roy"
To:
Sent: Thursday, March 01, 2007 1:39 PM
Subject: Re: Body reduction during bisque?
> Hi Dale,
>
> You've heard me going on about "clean" bisque firing before - best to fire
> bisque only in oxidation and make sure any organics are burned out -
> particularly when dealing with iron bearing bodies.
>
> Iron get reduced and turns into a very active flux and overvitrifies the
> clay - the result can be pin holes and blisters, blebbing and bloating.
>
> Bisque firing those iron bearing bodies in reduction can have exactly the
> same result.
>
> I suppose it could be possible - if your clay was too open and you needed
> more fluxing you could do it that way - Still better to make adjustments
> to
> the body and fire bisque in strictly oxidation.
>
> RR
>
>>Today I am doing something that I rarely have to do.
>>I am bisqueing in my gas kiln. Usually I bisque everything in my electric
>>kiln, all clays, whether they will be fired to cones6-7 in electric or
>>cone
>>10 in gas kiln. I have to use the gas kiln when I have a pot just too big
>>to
>>fit in the electric kiln, so, I load the gas kiln all up with everything I
>>can get in and bisque fire it to cone 04 (about 1920 degrees)..
>>Today I was wondering, does anyone who bisque fires in gas ever do
>>reduction
>>firing towards end of bisque? If so, do you find it really makes any
>>difference in body colors when they are then high fired? I always do a
>>body
>>reduction while high firing in the gas kiln but just wondered if it
>>accomplished anything if done during bisque, ESPECIALLY on clays that I
>>will
>>be later firing to cone6-7 IN THE ELECTRIC KILN instead of the gas kiln.
>>Anyone?
>>
>>Regards,
>>Dale
dalecochoy on thu 1 mar 07
OK Lee, if they are strong enough to handle for you.
I make a lot of multiple piece slab builts rectangles and ovals and some
are very heavy and large 20-24 inches , maybe used 50 lbs of clay to start.
I'd be afraid to handle them.
Plus, I used to have a lot of probs with my dark clays not bisqueing high
enough, so now I go to 04.
But....I'm not Japanese....so i may be doing it wrong! :>)
Thanks,
Dale Cochoy
Wild Things Bonsai Studio
Hartville, Ohio Zone 5
www.WildThingsBonsai.com
DaleCochoy@Prodigy.net
----- Original Message -----
From: "Lee Love"
To:
Sent: Thursday, March 01, 2007 7:17 PM
Subject: Re: Body reduction during bisque?
> On 3/2/07, dalecochoy wrote:
>
>> Lee,
>> You only bisque to cone 012 ?
>
> Much of the bottom of the kiln is at lower temp. Everyone
> bisques at lower temps here in Mashiko. I was first introduced to
> lower bisque by a Mashiko potter who was at Northern Clay Center.
> Toshi told me, "You Americans waist a lot of electricity!" (The
> average Japanese carbon footprint is 1/3rd of an American's.)
>
> But I also experienced it in the Noborigama bisques at
> Shimaoka's, where we only bisqued to dull red heat, which meant that
> most of the kiln was much cooler. But you have to be a better
> craftsman to work with soft bisque. 012 is not so difficult. You
> sponge clean the bisque with water and this controls the absorbency.
>
> Lower bisque seems to help shinos. You aren't burning out all that
> "good stuff" that the shino likes. It makes sense. Single fire
> works so why not low bisque?
>
> Folks who never bisque in wood don't realize that most of
> the prohibitions are related to industrial practices and are based on
> assumption (Old Wives' Tails) and not actual experience.
>
> All I have here is a wood kiln, though I have bisqued on my
> woodstove and that works well enough. I first heat the plates slowly
> in the electric oven (I keep it in the studio, so as not to heat the
> kitchen up in the summer), then up to maximum temp. I then took them
> out of the oven an put them on the wood stove, with a good fire going.
> I set the plates on top of the stove and then put fiber blanket on
> top.
>
> It bisque them enough to make them behave like normal
> bisque with shino on them. If I put shino on single fire, it all
> ends up looking like red latex paint. You can see one of the wood
> stove bisqued plates here:
>
> http://mashikopots.blogspot.com/2007/03/shino-plate-with-grass-decoration.html
>
> --
> Lee in Mashiko, Japan
> Minneapolis, Minnesota USA
> http://potters.blogspot.com/
>
> "To affect the quality of the day, that is the highest of arts." -
> Henry David Thoreau
>
> "Let the beauty we love be what we do." - Rumi
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
dalecochoy on thu 1 mar 07
My kiln naturally goes into reduction at about 012, my end bisque point.
No, it doesn't seem to have any effect on the glaze firing
and the clay body.
Lee,
You only bisque to cone 012 ?
Dale Cochoy
Wild Things Bonsai Studio
----- Original Message -----
From: "Lee Love"
To:
Sent: Wednesday, February 28, 2007 11:06 PM
Subject: Re: Body reduction during bisque?
> For new folks, I should add: I only have a wood fired kiln. I
> bisque in it and high fire in it.
>
>
> --
> Lee in Mashiko, Japan
> Minneapolis, Minnesota USA
> http://potters.blogspot.com/
Chris Trabka on thu 1 mar 07
Dale,
I have only one kiln, a gas fired MFT. In my bisque fire I always ensure
that the firing is always oxidation. Reducing during a bisque can lead to
black coring and bloating. John Britt in his new book "The Complete Guide
to High Fired Glazes" has a good discussion on bisque firing.
Chris
Ron Roy on thu 1 mar 07
Hi Dale,
You've heard me going on about "clean" bisque firing before - best to fire
bisque only in oxidation and make sure any organics are burned out -
particularly when dealing with iron bearing bodies.
Iron get reduced and turns into a very active flux and overvitrifies the
clay - the result can be pin holes and blisters, blebbing and bloating.
Bisque firing those iron bearing bodies in reduction can have exactly the
same result.
I suppose it could be possible - if your clay was too open and you needed
more fluxing you could do it that way - Still better to make adjustments to
the body and fire bisque in strictly oxidation.
RR
>Today I am doing something that I rarely have to do.
>I am bisqueing in my gas kiln. Usually I bisque everything in my electric
>kiln, all clays, whether they will be fired to cones6-7 in electric or cone
>10 in gas kiln. I have to use the gas kiln when I have a pot just too big to
>fit in the electric kiln, so, I load the gas kiln all up with everything I
>can get in and bisque fire it to cone 04 (about 1920 degrees)..
>Today I was wondering, does anyone who bisque fires in gas ever do reduction
>firing towards end of bisque? If so, do you find it really makes any
>difference in body colors when they are then high fired? I always do a body
>reduction while high firing in the gas kiln but just wondered if it
>accomplished anything if done during bisque, ESPECIALLY on clays that I will
>be later firing to cone6-7 IN THE ELECTRIC KILN instead of the gas kiln.
>Anyone?
>
>Regards,
>Dale
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ben Shelton on thu 1 mar 07
Ron, What is Blebbing?
Ben
Lee Love on fri 2 mar 07
On 3/2/07, dalecochoy wrote:
> OK Lee, if they are strong enough to handle for you.
Depends on the clay, but 012 is plenty strong enough. My larger
work is bisqued at the top of the kiln.
Shimaoka bisques his large stuff in his gas kiln, but only
to red heat.
> Plus, I used to have a lot of probs with my dark clays not bisqueing high
> enough, so now I go to 04.
You might try some different clay or change your glaze firing
schedual. My bizen clay has a lot of iron in it. So does my
Mashiko Red clay and neither are processed like commercial clays. I
sometimes single fire the bizen clay, with no problem. But it is
unglazed.
But, related to your original question, reduction doesn't
seem to effect the glaze firing in any way. A lower bisque does
seem to help shinos.
>But....I'm not Japanese....so i may be doing it wrong! :>)
Has nothing to do with ancestry. But experience helps. :^)
If you really want to play with a reduced bisque without doing it to a
whole kiln load, try pulling your pot and putting it in reduction
material. I pull raku pots out of my ware chamber and out of the
coal bed of the stoke chambers and reduce with newspaper in a small
container.
If I have time, I will record some tests for you. I plan on
pulling raku next firing and maybe some hikidashi. I saw a really
awesome show of Shino and Oribe ware at the Idemitsu last week.
They had some black and red raku on hand and explained how bizen,
shigaraki and the other unglazed kilns were influenced by raku as was
shino, seto guro and oribe.
They had two raku treasures that were not glossy at all, but
had mat surfaces. I bought the catalog and will put up some photos
when I get a chance.
Also, maybe 95% of shino had no red, but was white to
gray-white and blue. The red color only came from a very small area
of the kiln and those spots were reserved for tea bowls.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
Ron Roy on fri 2 mar 07
Hi Ben,
When a clay is overfired and starts to breakdown - gas is formed and
results in small blisters all over the ware. If the ware is heated further
and more melting occurs the "blisters" get bigger.
RR
>Ron, What is Blebbing?
>
>Ben
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Lee Love on fri 2 mar 07
On 3/2/07, dalecochoy wrote:
> Lee,
> You only bisque to cone 012 ?
Much of the bottom of the kiln is at lower temp. Everyone
bisques at lower temps here in Mashiko. I was first introduced to
lower bisque by a Mashiko potter who was at Northern Clay Center.
Toshi told me, "You Americans waist a lot of electricity!" (The
average Japanese carbon footprint is 1/3rd of an American's.)
But I also experienced it in the Noborigama bisques at
Shimaoka's, where we only bisqued to dull red heat, which meant that
most of the kiln was much cooler. But you have to be a better
craftsman to work with soft bisque. 012 is not so difficult. You
sponge clean the bisque with water and this controls the absorbency.
Lower bisque seems to help shinos. You aren't burning out all that
"good stuff" that the shino likes. It makes sense. Single fire
works so why not low bisque?
Folks who never bisque in wood don't realize that most of
the prohibitions are related to industrial practices and are based on
assumption (Old Wives' Tails) and not actual experience.
All I have here is a wood kiln, though I have bisqued on my
woodstove and that works well enough. I first heat the plates slowly
in the electric oven (I keep it in the studio, so as not to heat the
kitchen up in the summer), then up to maximum temp. I then took them
out of the oven an put them on the wood stove, with a good fire going.
I set the plates on top of the stove and then put fiber blanket on
top.
It bisque them enough to make them behave like normal
bisque with shino on them. If I put shino on single fire, it all
ends up looking like red latex paint. You can see one of the wood
stove bisqued plates here:
http://mashikopots.blogspot.com/2007/03/shino-plate-with-grass-decoration.html
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
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