Jon Singer on wed 3 nov 99
I'm with Jeff: I'm a student, I am (by his definition,
anyway) a hardcore, and I remember reading what
Robin Hopper has to say about what happened to him
when he washed some ash for half an hour without
gloves. (It's in "The Ceramic Spectrum", and it's not
nice. He couldn't throw for two weeks afterward.)
I'm a lab-klutz, and I'm much afraid that if I wore
gloves I'd just get the nice caustic liquid down inside
them. (Sigh.) As Jeff points out, there's also the problem
of breaking the stuff back up into bits after you wash
and dry it. This is all too much for me, so I use it
without washing it.
I sift my ash with a coarse (10-mesh) sieve to get the
really large chunks of charcoal and junk out. Then I
put it into the glaze and typically pour the batch
through a finer (60-mesh) sieve.
I usually try not to touch the glaze, but when I do, it
doesn't usually have that slippery caustic feel. (I wash
it off quickly anyway -- better safe than sorry. Also,
whenever I'm dealing with dry pottery materials, I
wear a HEPA-filter mask. It's weird, but I've gotten
used to it, and my asthma thanks me.)
Has anyone tried neutralizing unwashed ash with
vinegar? Does it do anything good ...or bad... to
the glaze? I'm going to try sticking some pH test
paper into my current batch tomorrow, to see what
the actual pH is. If it's grossly surprising, I may put
a report here.
Best --
jon
Jeff Campana on thu 4 nov 99
Jon,
As a fellow hardcore, i took the liberty of looking up the Ph of unwashed
ash in Tichane's Ash Glazes. Get this: 12! Now that's caustic! Anyway,
I would recommend that book to about anybody who has an interest in the use
of any type of ash. It has charts of about every ash i can think of, and
he shares philosophies of ash, not to mention, he's a fellow hardcare
non-washer too. To prevent my hands from being eaten, I bought a sprayer,
and we have a nice ventilated spray booth here in Whitewater, so i just
spray it--no gloves, no washing. Also with the sprayer, I tried spraying a
mix of 75 wood ash, 25 rutile powder over a Temoku. It yeilded a nice
mottled hare's fur looking glaze in high reduction, and I'm anxiously
awaiting my salt test, which i will unload tommorow.
Lots of luck
Jeff Campana
Jon Singer wrote:
> ----------------------------Original message----------------------------
> I'm with Jeff: I'm a student, I am (by his definition,
> anyway) a hardcore, and I remember reading what
> Robin Hopper has to say about what happened to him
> when he washed some ash for half an hour without
> gloves. (It's in "The Ceramic Spectrum", and it's not
> nice. He couldn't throw for two weeks afterward.)
>
> I'm a lab-klutz, and I'm much afraid that if I wore
> gloves I'd just get the nice caustic liquid down inside
> them. (Sigh.) As Jeff points out, there's also the problem
> of breaking the stuff back up into bits after you wash
> and dry it. This is all too much for me, so I use it
> without washing it.
>
> I sift my ash with a coarse (10-mesh) sieve to get the
> really large chunks of charcoal and junk out. Then I
> put it into the glaze and typically pour the batch
> through a finer (60-mesh) sieve.
>
> I usually try not to touch the glaze, but when I do, it
> doesn't usually have that slippery caustic feel. (I wash
> it off quickly anyway -- better safe than sorry. Also,
> whenever I'm dealing with dry pottery materials, I
> wear a HEPA-filter mask. It's weird, but I've gotten
> used to it, and my asthma thanks me.)
>
> Has anyone tried neutralizing unwashed ash with
> vinegar? Does it do anything good ...or bad... to
> the glaze? I'm going to try sticking some pH test
> paper into my current batch tomorrow, to see what
> the actual pH is. If it's grossly surprising, I may put
> a report here.
>
> Best --
> jon
Donald G. Goldsobel on thu 4 nov 99
I have processed ash and used it washed and unwashed. There is just as
much peril from caustic substance during washing as from the raw ash glaze
during use. I sift the ash to remove the big junk and use it straight or
mix it 50\50 by weight with a tenmoku glaze and use it over the tenmoku
(great results) The ash loses character when it is washed, just how much
depends on the type of ash. I favor eucalyptus\conifer fireplace ash, but
more exotic results are found in fruit wood ( is that one word or two?)
ash, especially apple. To a large extent the result has a lot to do with
the soil where the tree ( or soft plant material) grew. The best results
I've had are when mixing it wit tenmoku and glazing the upper portion of
the pot, so the ash can thread and drip down.
Donald G. in the San Fernando Valley where it is starting to cool, my new
irises are taking root and the sunrises are glorious.
>----------------------------Original message----------------------------
>I'm with Jeff: I'm a student, I am (by his definition,
>anyway) a hardcore, and I remember reading what
>Robin Hopper has to say about what happened to him
>when he washed some ash for half an hour without
>gloves. (It's in "The Ceramic Spectrum", and it's not
>nice. He couldn't throw for two weeks afterward.)
>
>I'm a lab-klutz, and I'm much afraid that if I wore
>gloves I'd just get the nice caustic liquid down inside
>them. (Sigh.) As Jeff points out, there's also the problem
>of breaking the stuff back up into bits after you wash
>and dry it. This is all too much for me, so I use it
>without washing it.
>
>I sift my ash with a coarse (10-mesh) sieve to get the
>really large chunks of charcoal and junk out. Then I
>put it into the glaze and typically pour the batch
>through a finer (60-mesh) sieve.
>
>I usually try not to touch the glaze, but when I do, it
>doesn't usually have that slippery caustic feel. (I wash
>it off quickly anyway -- better safe than sorry. Also,
>whenever I'm dealing with dry pottery materials, I
>wear a HEPA-filter mask. It's weird, but I've gotten
>used to it, and my asthma thanks me.)
>
>Has anyone tried neutralizing unwashed ash with
>vinegar? Does it do anything good ...or bad... to
>the glaze? I'm going to try sticking some pH test
>paper into my current batch tomorrow, to see what
>the actual pH is. If it's grossly surprising, I may put
>a report here.
>
>Best --
>jon
>
Earl Brunner on thu 4 nov 99
If the weight of the ash isn't critical (as in a glaze formula) then the ash
wouldn't need to be dried out after the wash, just let it settle out and
pour off the water and change it to get the soluables out. When I use ash
though, Since I don't bother washing it I don't worry about the soluables.
I have some industrial rubber gloves that I got at a safety store that
supplies safety equipment to businesses that have to comply with government
safety standards. They are heavy duty and go up to my elbow. Really nice
for stirring glaze.
Jon Singer wrote:
> ----------------------------Original message----------------------------
> I'm with Jeff: I'm a student, I am (by his definition,
> anyway) a hardcore, and I remember reading what
> Robin Hopper has to say about what happened to him
> when he washed some ash for half an hour without
> gloves. (It's in "The Ceramic Spectrum", and it's not
> nice. He couldn't throw for two weeks afterward.)
>
> I'm a lab-klutz, and I'm much afraid that if I wore
> gloves I'd just get the nice caustic liquid down inside
> them. (Sigh.) As Jeff points out, there's also the problem
> of breaking the stuff back up into bits after you wash
> and dry it. This is all too much for me, so I use it
> without washing it.
>
> I sift my ash with a coarse (10-mesh) sieve to get the
> really large chunks of charcoal and junk out. Then I
> put it into the glaze and typically pour the batch
> through a finer (60-mesh) sieve.
>
> I usually try not to touch the glaze, but when I do, it
> doesn't usually have that slippery caustic feel. (I wash
> it off quickly anyway -- better safe than sorry. Also,
> whenever I'm dealing with dry pottery materials, I
> wear a HEPA-filter mask. It's weird, but I've gotten
> used to it, and my asthma thanks me.)
>
> Has anyone tried neutralizing unwashed ash with
> vinegar? Does it do anything good ...or bad... to
> the glaze? I'm going to try sticking some pH test
> paper into my current batch tomorrow, to see what
> the actual pH is. If it's grossly surprising, I may put
> a report here.
>
> Best --
> jon
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
susanford on fri 5 nov 99
I've got that book, and Phil Roger's on on Ash Glazes. I am
going to do some tests with ash and other materials to see
if I can come up with something interesting at cone 6.
Tichane's book is a bit over my head, but I understand more
of it each time I read it.
Since I have a fireplace, I've got a pretty good source for
ash, and there is plenty still there, at the base of the
chimney. Would be nice to have a free source of at least
one glaze material. It's mostly hardwood - scrub oak.
Susan
> Jon,
> As a fellow hardcore, i took the liberty of looking up the Ph of unwashed
> ash in Tichane's Ash Glazes. Get this: 12! Now that's caustic! Anyway,
> I would recommend that book to about anybody who has an interest in the use
> of any type of ash. It has charts of about every ash i can think of, and
> he shares philosophies of ash, not to mention, he's a fellow hardcare
> non-washer too. To prevent my hands from being eaten, I bought a sprayer,
> and we have a nice ventilated spray booth here in Whitewater, so i just
> spray it--no gloves, no washing. Also with the sprayer, I tried spraying a
> mix of 75 wood ash, 25 rutile powder over a Temoku. It yeilded a nice
> mottled hare's fur looking glaze in high reduction, and I'm anxiously
> awaiting my salt test, which i will unload tommorow.
>
> Lots of luck
>
> Jeff Campana
>
> Jon Singer wrote:
>
> > ----------------------------Original message----------------------------
> > I'm with Jeff: I'm a student, I am (by his definition,
> > anyway) a hardcore, and I remember reading what
> > Robin Hopper has to say about what happened to him
> > when he washed some ash for half an hour without
> > gloves. (It's in "The Ceramic Spectrum", and it's not
> > nice. He couldn't throw for two weeks afterward.)
> >
> > I'm a lab-klutz, and I'm much afraid that if I wore
> > gloves I'd just get the nice caustic liquid down inside
> > them. (Sigh.) As Jeff points out, there's also the problem
> > of breaking the stuff back up into bits after you wash
> > and dry it. This is all too much for me, so I use it
> > without washing it.
> >
> > I sift my ash with a coarse (10-mesh) sieve to get the
> > really large chunks of charcoal and junk out. Then I
> > put it into the glaze and typically pour the batch
> > through a finer (60-mesh) sieve.
> >
> > I usually try not to touch the glaze, but when I do, it
> > doesn't usually have that slippery caustic feel. (I wash
> > it off quickly anyway -- better safe than sorry. Also,
> > whenever I'm dealing with dry pottery materials, I
> > wear a HEPA-filter mask. It's weird, but I've gotten
> > used to it, and my asthma thanks me.)
> >
> > Has anyone tried neutralizing unwashed ash with
> > vinegar? Does it do anything good ...or bad... to
> > the glaze? I'm going to try sticking some pH test
> > paper into my current batch tomorrow, to see what
> > the actual pH is. If it's grossly surprising, I may put
> > a report here.
> >
> > Best --
> > jon
>
>
---
Susan K. Ford
Norman, Oklahoma
http://www.clueless.norman.ok.us/sf/rerhome.htm
Hank Murrow on fri 5 nov 99
>----------------------------Original message----------------------------
>
>
> I have processed ash and used it washed and unwashed. There is just as
>much peril from caustic substance during washing as from the raw ash glaze
>during use. I sift the ash to remove the big junk and use it straight or
>mix it 50\50 by weight with a tenmoku glaze and use it over the tenmoku
>(great results) The ash loses character when it is washed, just how much
>depends on the type of ash. I favor eucalyptus\conifer fireplace ash, but
>more exotic results are found in fruit wood ( is that one word or two?)
>ash, especially apple. To a large extent the result has a lot to do with
>the soil where the tree ( or soft plant material) grew. The best results
>I've had are when mixing it wit tenmoku and glazing the upper portion of
>the pot, so the ash can thread and drip down.
>
>Donald G.
Dear Donald; Mr. Hamada at a workshop in CA in '63 or so suggested that the
job the plant (or part of a plant) does will suggest its mineral content.
Rice hulls are doing the job of protecting the kernel of seed, so when you
burn it you get mostly Silica. Fruit wood, on the other hand, will be high
in Phosphorus, especially as you get out near the fruit; as that's what
fruit needs. Once at the U of Oregon we calcined several garbage can sized
loads of post-pressing apple pulp. The result was an ash loaded with
Phosphorus yielding marvelous iron blues. I use a local Andesite(somewhat
less basic than Basalt) and a small amount of unwashed Madrone ash to yeild
a wonderful clone of Black Seto when pulled from the kiln at C/11+ and air
cooled. Has a most wonderful irridescence due, I believe, to the soluble
salts from the unwashed ash. Good Hunting! Hank in Eugene
Ronan ORourke on sat 6 nov 99
-----Original Message-----
From: Hank Murrow
To: CLAYART@LSV.UKY.EDU
Date: 05 November 1999 16:56
Subject: Re: Ash washing & Jeff Campana's posting --
>snip
>I use a local Andesite(somewhat
>less basic than Basalt) and a small amount of unwashed Madrone ash >to
yeild
>a wonderful clone of Black Seto when pulled from the kiln at C/11+ and >air
>cooled
Can you run that one by me again, pulled from the kiln at C/11+ and air
cooled ?!!?!
Wow! There must be some serious thermal shock going on there.
Not to mention the heat from opening a kiln wide enough to pull any but the
smallest pot out, lengthy tongs would be in order!
Is this process wide spread? I've come across high temperature raku,
but ^11.
Please tell us more, I'm intrigued.
Ronan,
In rainy Wolverhampton, hopping it clears up for tonight's Guy Forks
celebrations.
Hank Murrow on sun 7 nov 99
>----------------------------Original message----------------------------
>
>-----Original Message-----
>From: Hank Murrow
>To: CLAYART@LSV.UKY.EDU
>Date: 05 November 1999 16:56
>Subject: Re: Ash washing & Jeff Campana's posting --
>>snip
>
>>I use a local Andesite(somewhat
>>less basic than Basalt) and a small amount of unwashed Madrone ash >to
>yeild
>>a wonderful clone of Black Seto when pulled from the kiln at C/11+ and >air
>>cooled
>
> Can you run that one by me again, pulled from the kiln at C/11+ and air
>cooled ?!!?!
> Wow! There must be some serious thermal shock going on there.
>Not to mention the heat from opening a kiln wide enough to pull any but the
>smallest pot out, lengthy tongs would be in order!
> Is this process wide spread? I've come across high temperature raku,
>but ^11.
> Please tell us more, I'm intrigued.
>
>Ronan,
> In rainy Wolverhampton, hopping it clears up for tonight's Guy Forks
>celebrations.
Dear Ronan; I do indeed use a local andesite(like Basalt, but less MgO and
Fe, and more Si) mixed with a 'touch'(6%) of unwashed Madrone ash. The
andesite from the vicinity of the Santiam River is majorly weathered; so
The teabowl must be glazed raw to minimize the shrinkage differential, but
still yielding a wonderful crawl pattern which shows up, after the fire has
healed it, as a 'tortoise shell' pattern. The clay is a standard stoneware
to which I add 5% or so of "Thermal Grain" from Foote Mineral Co. for
thermal shock resistance. The pots are fired in an anagama, placed just
near the stoke ports. When the kiln is just ready to be sealed up after the
fire, The bowls are pulled out and aircooled. Some have a 'Raven's-wing'
lustre to them; all are wonderful with thick green Matcha tea. My goal is
to get a couple of winners to send to the Freer Gallery as a thank you for
showing me their collection of Black Seto teabowls some years ago; which
since I can't afford to own one....decided to make some. Took me two years.
Waiting for the next anagama fire in Eugene, Hank
Stephen Grimmer on sun 7 nov 99
Ronan,
It's true: there are a small number of folks pulling pots out of kilns
at high heat. One of our grad students here at BGSU has been pulling pots
out of the our wood kiln at ^6 and is getting some real promising Black Seto
renditions. His clay is made up of Roseville stoneware, wild Virginia clay
with inclusions, and Kyanite. He has another body made up of fireclay and
alumina. He pulls the pots out of both the main firebox and from the side
stokes with a long steel rod and drops them straight into a bucket of water.
Four days to fire, forty seconds to cool!
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Ronan ORourke
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: Ash washing & Jeff Campana's posting --
>Date: Sat, Nov 6, 1999, 7:51 PM
>
>----------------------------Original message----------------------------
>
>-----Original Message-----
>From: Hank Murrow
>To: CLAYART@LSV.UKY.EDU
>Date: 05 November 1999 16:56
>Subject: Re: Ash washing & Jeff Campana's posting --
>>snip
>
>>I use a local Andesite(somewhat
>>less basic than Basalt) and a small amount of unwashed Madrone ash >to
>yeild
>>a wonderful clone of Black Seto when pulled from the kiln at C/11+ and >air
>>cooled
>
> Can you run that one by me again, pulled from the kiln at C/11+ and air
>cooled ?!!?!
> Wow! There must be some serious thermal shock going on there.
>Not to mention the heat from opening a kiln wide enough to pull any but the
>smallest pot out, lengthy tongs would be in order!
> Is this process wide spread? I've come across high temperature raku,
>but ^11.
> Please tell us more, I'm intrigued.
>
>Ronan,
> In rainy Wolverhampton, hopping it clears up for tonight's Guy Forks
>celebrations.
Ronan ORourke on tue 9 nov 99
Dear Hank and Stephen
thank you both for your replies. The fact that you both refer to this
as a woodfire process has me even more intrigued. Over the summer I built a
woodfired kiln which is about to get its second outing.
This is certainly something I will experiment with. Is it just Black
Seto glazes which benefit from this process or will it enhance other glazes
too?
I will try to source some Andesite or Basalt. If I am unable to get
hold of these might it be worth trying a feldspar / ash/ red clay triaxal?
Thanks again
Ronan.
-----Original Message-----
From: Hank Murrow
To: CLAYART@LSV.UKY.EDU
Date: 07 November 1999 22:23
Subject: Re: Ash washing & Jeff Campana's posting --
----------------------------Original message----------------------------
>----------------------------Original message----------------------------
>
>-----Original Message-----
>From: Hank Murrow
>To: CLAYART@LSV.UKY.EDU
>Date: 05 November 1999 16:56
>Subject: Re: Ash washing & Jeff Campana's posting --
>>snip
>
>>I use a local Andesite(somewhat
>>less basic than Basalt) and a small amount of unwashed Madrone ash >to
>yeild
>>a wonderful clone of Black Seto when pulled from the kiln at C/11+ and
>air
>>cooled
>
> Can you run that one by me again, pulled from the kiln at C/11+ and air
>cooled ?!!?!
> Wow! There must be some serious thermal shock going on there.
>Not to mention the heat from opening a kiln wide enough to pull any but the
>smallest pot out, lengthy tongs would be in order!
> Is this process wide spread? I've come across high temperature raku,
>but ^11.
> Please tell us more, I'm intrigued.
>
>Ronan,
> In rainy Wolverhampton, hopping it clears up for tonight's Guy Forks
>celebrations.
Dear Ronan; I do indeed use a local andesite(like Basalt, but less MgO and
Fe, and more Si) mixed with a 'touch'(6%) of unwashed Madrone ash. The
andesite from the vicinity of the Santiam River is majorly weathered; so
The teabowl must be glazed raw to minimize the shrinkage differential, but
still yielding a wonderful crawl pattern which shows up, after the fire has
healed it, as a 'tortoise shell' pattern. The clay is a standard stoneware
to which I add 5% or so of "Thermal Grain" from Foote Mineral Co. for
thermal shock resistance. The pots are fired in an anagama, placed just
near the stoke ports. When the kiln is just ready to be sealed up after the
fire, The bowls are pulled out and aircooled. Some have a 'Raven's-wing'
lustre to them; all are wonderful with thick green Matcha tea. My goal is
to get a couple of winners to send to the Freer Gallery as a thank you for
showing me their collection of Black Seto teabowls some years ago; which
since I can't afford to own one....decided to make some. Took me two years.
Waiting for the next anagama fire in Eugene, Hank
Martin Howard on wed 10 nov 99
Ronan wrote:-
I will try to source some Andesite or Basalt. If I am unable to get
hold of these might it be worth trying a feldspar / ash/ red clay triaxal?
Why not have a word with your local monumental mason. Much of what comes
from the diamond saw is andesite, basalt and similar, even though it might
be called marble. And it should be free, if you get down there and clear out
the collecting tray or sump. Lovely stuff.
Martin Howard
Webbs Cottage Pottery
Woolpits Road
Great Saling
BRAINTREE
Essex CM7 5DZ
martin@webbscottage.co.uk
Stephen Grimmer on wed 10 nov 99
Ronan,
I suppose the way to find out is to apply your glazes to a bowl and pull
it out at temperature. I imagine it will certainly change your glaze, but
only you can say if it's for the better!
There are numerous good glazes to be found in most triaxals with red
clay, flux (ash, whiting, barium, wollastonite, strontium, talc, dolomite,
etc), and spar. Some will be quite fluid as you get closer to the clay/flux
baseline, some will be glossy, some matte. Add iron and a percent or two of
cobalt to the nice amber glossy and you get a black slip glaze (usually!).
Further testing can eliminate crazing and really fine tune the glaze.
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Ronan ORourke
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: Ash washing & Jeff Campana's posting --
>Date: Tue, Nov 9, 1999, 11:56 AM
>
>----------------------------Original message----------------------------
>Dear Hank and Stephen
> thank you both for your replies. The fact that you both refer to this
>as a woodfire process has me even more intrigued. Over the summer I built a
>woodfired kiln which is about to get its second outing.
> This is certainly something I will experiment with. Is it just Black
>Seto glazes which benefit from this process or will it enhance other glazes
>too?
> I will try to source some Andesite or Basalt. If I am unable to get
>hold of these might it be worth trying a feldspar / ash/ red clay triaxal?
>
>Thanks again
> Ronan.
>
>-----Original Message-----
>From: Hank Murrow
>To: CLAYART@LSV.UKY.EDU
>Date: 07 November 1999 22:23
>Subject: Re: Ash washing & Jeff Campana's posting --
>
>
>----------------------------Original message----------------------------
>>----------------------------Original message----------------------------
>>
>>-----Original Message-----
>>From: Hank Murrow
>>To: CLAYART@LSV.UKY.EDU
>>Date: 05 November 1999 16:56
>>Subject: Re: Ash washing & Jeff Campana's posting --
>>>snip
>>
>>>I use a local Andesite(somewhat
>>>less basic than Basalt) and a small amount of unwashed Madrone ash >to
>>yeild
>>>a wonderful clone of Black Seto when pulled from the kiln at C/11+ and
>>air
>>>cooled
>>
>> Can you run that one by me again, pulled from the kiln at C/11+ and air
>>cooled ?!!?!
>> Wow! There must be some serious thermal shock going on there.
>>Not to mention the heat from opening a kiln wide enough to pull any but the
>>smallest pot out, lengthy tongs would be in order!
>> Is this process wide spread? I've come across high temperature raku,
>>but ^11.
>> Please tell us more, I'm intrigued.
>>
>>Ronan,
>> In rainy Wolverhampton, hopping it clears up for tonight's Guy Forks
>>celebrations.
>
>Dear Ronan; I do indeed use a local andesite(like Basalt, but less MgO and
>Fe, and more Si) mixed with a 'touch'(6%) of unwashed Madrone ash. The
>andesite from the vicinity of the Santiam River is majorly weathered; so
>The teabowl must be glazed raw to minimize the shrinkage differential, but
>still yielding a wonderful crawl pattern which shows up, after the fire has
>healed it, as a 'tortoise shell' pattern. The clay is a standard stoneware
>to which I add 5% or so of "Thermal Grain" from Foote Mineral Co. for
>thermal shock resistance. The pots are fired in an anagama, placed just
>near the stoke ports. When the kiln is just ready to be sealed up after the
>fire, The bowls are pulled out and aircooled. Some have a 'Raven's-wing'
>lustre to them; all are wonderful with thick green Matcha tea. My goal is
>to get a couple of winners to send to the Freer Gallery as a thank you for
>showing me their collection of Black Seto teabowls some years ago; which
>since I can't afford to own one....decided to make some. Took me two years.
>Waiting for the next anagama fire in Eugene, Hank
Hank Murrow on thu 11 nov 99
Good Morning Steve & Ronan; A few words about Black Seto may be in
order, so bear with me. In the mid 1500s potters at the Seto kilns finally
benefited from some military trickledown and were allowed to have iron
tools made for them. Now they were finally able to pull draw trials from
their anagamas; and they were no doubt surprised to see the saturated-iron
glazes come out blackish on the drawrings instead of rusty. The iron was
trapped in the black reduced form of the oxide by the quick cooling, while
the same glazes remaining in the kiln for a normal cooling had time to
crystalize to rust colors. They soon figured out that they could increase
the iron content to get a truly deep black (which if left in the kiln would
be terribly scummed with precipitated metal) which the Tea masters loved
for its contrast with the frothy green matcha tea. Trouble was, they could
only pull a few from the stoke holes in each firing, so these wares were
relatively scarce. Of couse, by about 1600, Hideyoshi brought back potters
from Korea who introduced the new Noborigama (multi chambered) kiln design;
and long firings were out, higher temperatures were achieved, and the Shino
glazes started looking like Oribe. Arakawa ressurected the process in the
thrirties when he built his famous anagama near the site of the original
Shino kilns. Gorgeous Shino and Black Seto pieces were produced there by
him.
Cut to the present, and your local anagama has those wonderfully
large stoke holes and you can place a tea bowl or two where you can reach
them at the end of the firing. You can take a weathered andesite (KNa .24,
Ca .44, Mg .31, Fe .26, Al .81, & Si 3.8)and add a little unwashed wood ash
(for melt & irridescence) and because it's so plastic, green glaze your
bowl or vase(for a nice crawl) and pull it out of the anagama for a quick
cool and a black glaze with some nice tong marks for decoration. Or, you
could take any Tenmoku recipe and add enough iron to more than saturate it
if left to cool in the kiln; and get a black that way. Cobalt additions
will not give the color I prize. I am describing an very thick absolutely
jet black with a sort of raven's wing irridescence, and a tortoiseshell
pattern where the crawl heals over.
And you don't need an anagama! Those who have borne with me so far
have realized that you just need a kiln with a humongous spyhole, or some
other aperture big enough to reach in and grab some pots. I have grown
impatient with the longish waits between anagama fires and the increasing
competition for that choice space near a stokehole; so I am building a
small experimental kiln which will have generous and frequent openings to
retreive pots in the way I've described. These wares don't really need an
anagama, and I need to fire them much more often if I am to produce any
good wares reliably. Hope this clarifies the former posts and whets
everyone's apetite! Hank in Eugene
___________________________original message____________________________________
>Dear Ronan; I do indeed use a local andesite(like Basalt, but less MgO and
>Fe, and more Si) mixed with a 'touch'(6%) of unwashed Madrone ash. The
>andesite from the vicinity of the Santiam River is majorly weathered; so
>The teabowl must be glazed raw to minimize the shrinkage differential, but
>still yielding a wonderful crawl pattern which shows up, after the fire has
>healed it, as a 'tortoise shell' pattern. The clay is a standard stoneware
>to which I add 5% or so of "Thermal Grain" from Foote Mineral Co. for
>thermal shock resistance. The pots are fired in an anagama, placed just
>near the stoke ports. When the kiln is just ready to be sealed up after the
>fire, The bowls are pulled out and aircooled. Some have a 'Raven's-wing'
>lustre to them; all are wonderful with thick green Matcha tea. My goal is
>to get a couple of winners to send to the Freer Gallery as a thank you for
>showing me their collection of Black Seto teabowls some years ago; which
>since I can't afford to own one....decided to make some. Took me two years.
>Waiting for the next anagama fire in Eugene, Hank
>----------------------------Original message----------------------------
>Dear Hank and Stephen
> thank you both for your replies. The fact that you both refer to this
>as a woodfire process has me even more intrigued. Over the summer I built a
>woodfired kiln which is about to get its second outing.
> This is certainly something I will experiment with. Is it just Black
>Seto glazes which benefit from this process or will it enhance other glazes
>too?
> I will try to source some Andesite or Basalt. If I am unable to get
>hold of these might it be worth trying a feldspar / ash/ red clay triaxal?
>
>Thanks again
> Ronan.
Ronan,
I suppose the way to find out is to apply your glazes to a bowl and pull
it out at temperature. I imagine it will certainly change your glaze, but
only you can say if it's for the better!
There are numerous good glazes to be found in most triaxals with red
clay, flux (ash, whiting, barium, wollastonite, strontium, talc, dolomite,
etc), and spar. Some will be quite fluid as you get closer to the clay/flux
baseline, some will be glossy, some matte. Add iron and a percent or two of
cobalt to the nice amber glossy and you get a black slip glaze (usually!).
Further testing can eliminate crazing and really fine tune the glaze.
Steve Grimmer
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