Jennifer Boyer on thu 17 may 07
This web page has some pix of a Khaki Red glaze I'm using based on
the Anderson Ranch khaki in John Britt's stoneware glaze book:
http://www.thistlehillpottery.com/teapots.html
I'm trying to figure out why this glaze looks different in these 2
tests. My guess is that the left hand test fired hotter and also was
soaked longer so that crystals formed. This mottling happens(I think)
more in the area nearer to the flame path of the burners, hence my
guess about the hotter temp.. But these 2 variations of the glaze can
show up in the same firing pretty close to each other! It could be
that it's purely a temperature issue, with the crystals forming as
the glaze gets fired hotter. OR it could be that the glaze gets
mottled when appled thicker...What do you think?
I've been selling this glaze on vases, etc and revelling in the
variation: check out the left hand vase in the pic on the page noted
above. It's truly a ZINGER.
BUT I have a wedding registry for red dinnerware, so by August I need
to understand how to get more consistency for a set of plates....
Jennifer, planning many more tests and appreciating John's book,
since I have more tools for testing productively....
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
David Beumee on thu 17 may 07
Hi Jennifer,
In the photo of your tests above the photo of the vases, the mottling is on the test on the left of the photo, and also the vase to the right of the lower "2 vases" photo.
I have used Val's Tomato Red, the recipe just to the right of the Anderson Ranch recipe in John Britt's book, page 74. Although I'm not familiar with the Anderson Ranch recipe in my kiln, the result looks identical to what can happen with Val's Tomato Red. John Britt is no doubt correct that application thickness has alot to do with the ability of the glaze to come out orange instead of the mottled, "leopard spots." But my experience of fifteen years firing Val's Tomato Red in reduction at cone 10 is that prolonged reoxidation at the end of the firing is key to producing the orange color. You say you soak 40 minutes when you reach temperature. Is the soak in oxidation? My experience is that it takes time at top temperature for black iron oxide to reoxidize into red iron oxide, giving the orange color. 40 minutes of soak in straight oxidation should be plenty to produce an all-over orange color.
Best of luck with your dinnerware order.
David Beumee
Porcelain by David Beumee
Lafayette, CO
-------------- Original message ----------------------
From: Jennifer Boyer
>
> This web page has some pix of a Khaki Red glaze I'm using based on
> the Anderson Ranch khaki in John Britt's stoneware glaze book:
>
> http://www.thistlehillpottery.com/teapots.html
>
> I'm trying to figure out why this glaze looks different in these 2
> tests. My guess is that the left hand test fired hotter and also was
> soaked longer so that crystals formed. This mottling happens(I think)
> more in the area nearer to the flame path of the burners, hence my
> guess about the hotter temp.. But these 2 variations of the glaze can
> show up in the same firing pretty close to each other! It could be
> that it's purely a temperature issue, with the crystals forming as
> the glaze gets fired hotter. OR it could be that the glaze gets
> mottled when appled thicker...What do you think?
>
> I've been selling this glaze on vases, etc and revelling in the
> variation: check out the left hand vase in the pic on the page noted
> above. It's truly a ZINGER.
> BUT I have a wedding registry for red dinnerware, so by August I need
> to understand how to get more consistency for a set of plates....
> Jennifer, planning many more tests and appreciating John's book,
> since I have more tools for testing productively....
>
>
>
> *****************************
> Jennifer Boyer
> Thistle Hill Pottery
> Montpelier, VT
> http://thistlehillpottery.com
> *****************************
>
> ______________________________________________________________________________
> 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.
Eva Gallagher on thu 17 may 07
Hi Jennifer -
We too have been doing lots of experiments with John's fantastic book.
Perhaps the non crystalline is thinner - does the glaze settle out as I see
it does not have that much kaolin in it. The Johnston Temmoku from the book
settles really quick in the top few centimetres - so even if dipping after a
few minutes and just dipping shallow like a test tile will give a much
thinner coat.
We have found Bailey's Red very reliable - it looks just like the plate in
the book.
Regards,
Eva Gallagher
Deep River, Ontario
----- Original Message -----
From: "Jennifer Boyer"
To:
Sent: Thursday, May 17, 2007 8:13 AM
Subject: Khaki Red Glaze variations
> This web page has some pix of a Khaki Red glaze I'm using based on
> the Anderson Ranch khaki in John Britt's stoneware glaze book:
>
> http://www.thistlehillpottery.com/teapots.html
>
> I'm trying to figure out why this glaze looks different in these 2
> tests. My guess is that the left hand test fired hotter and also was
> soaked longer so that crystals formed. This mottling happens(I think)
> more in the area nearer to the flame path of the burners, hence my
> guess about the hotter temp.. But these 2 variations of the glaze can
> show up in the same firing pretty close to each other! It could be
> that it's purely a temperature issue, with the crystals forming as
> the glaze gets fired hotter. OR it could be that the glaze gets
> mottled when appled thicker...What do you think?
>
> I've been selling this glaze on vases, etc and revelling in the
> variation: check out the left hand vase in the pic on the page noted
> above. It's truly a ZINGER.
> BUT I have a wedding registry for red dinnerware, so by August I need
> to understand how to get more consistency for a set of plates....
> Jennifer, planning many more tests and appreciating John's book,
> since I have more tools for testing productively....
>
>
>
> *****************************
> Jennifer Boyer
> Thistle Hill Pottery
> Montpelier, VT
> http://thistlehillpottery.com
> *****************************
>
> ______________________________________________________________________________
> 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.
>
Dave Finkelnburg on thu 17 may 07
Jennifer,
I have not tested this particular glaze, nor
investigated iron reds exhaustively, but in my
experience with them I think you have most of the
variables sorted out. I would add glaze thickness as
a possible contributor. I would expect a thicker
glaze coat to be more likely to appear as the glaze on
the left since it will, in general, have less alumina
and silica relative to flux.
Good potting!
Dave Finkelnburg
From: Jennifer Boyer wrote:
This web page has some pix of a Khaki Red glaze I'm
using based on the Anderson Ranch khaki in John
Britt's stoneware glaze book:
http://www.thistlehillpottery.com/teapots.html
I'm trying to figure out why this glaze looks
different in these 2 tests.
____________________________________________________________________________________Get the Yahoo! toolbar and be alerted to new email wherever you're surfing.
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Jennifer Boyer on thu 17 may 07
Hi David,
As to oxidation, I fire my kiln in oxidation or neutral atmosphere. I
try to stay under -.10 on my oxyprobe. This varies and sometimes I
go as far as -.20, but I try not to as I have a white glaze that I
try to keep from getting speckly(now, now, no eye rolling!). My soak
at the end is easy to do in oxidation since I'm stalling the kiln,
but I'm glad to have your input and will try a more oxidizing
atmosphere at the end. You don't think it has anything to do with
over or under firing?
I know that one critical issue with a high iron glaze is that iron
oxide fluxes more when reduced, so if you stay in oxidation you lower
the melting temp of the glaze. I also think that if you do reduce the
glaze and it gets glossy there may be more of a tendency for the
glaze to produce what look to me like crystalline structures.
Looks like I have a number of factors to consider!
Jennifer
PS You make gorgeous pots! And through modesty you don't include your
web site in your posts?
Check it out everyone: http://www.davidbeumee.com/
On May 17, 2007, at 1:04 PM, claybuds@att.net wrote:
> Hi Jennifer,
> In the photo of your tests above the photo of the vases, the
> mottling is on the test on the left of the photo, and also the vase
> to the right of the lower "2 vases" photo.
> I have used Val's Tomato Red, the recipe just to the right of the
> Anderson Ranch recipe in John Britt's book, page 74. Although I'm
> not familiar with the Anderson Ranch recipe in my kiln, the result
> looks identical to what can happen with Val's Tomato Red. John
> Britt is no doubt correct that application thickness has alot to do
> with the ability of the glaze to come out orange instead of the
> mottled, "leopard spots." But my experience of fifteen years firing
> Val's Tomato Red in reduction at cone 10 is that prolonged
> reoxidation at the end of the firing is key to producing the orange
> color. You say you soak 40 minutes when you reach temperature. Is
> the soak in oxidation? My experience is that it takes time at top
> temperature for black iron oxide to reoxidize into red iron oxide,
> giving the orange color. 40 minutes of soak in straight oxidation
> should be plenty to produce an all-over orange color.
> Best of luck with your dinnerware order.
>
> David Beumee
> Porcelain by David Beumee
> Lafayette, CO
>
>
>
>
>
>
>
>
>
>
>
>
>
> -------------- Original message ----------------------
> From: Jennifer Boyer
>>
>> This web page has some pix of a Khaki Red glaze I'm using based on
>> the Anderson Ranch khaki in John Britt's stoneware glaze book:
>>
>> http://www.thistlehillpottery.com/teapots.html
>>
>> I'm trying to figure out why this glaze looks different in these 2
>> tests. My guess is that the left hand test fired hotter and also was
>> soaked longer so that crystals formed. This mottling happens(I think)
>> more in the area nearer to the flame path of the burners, hence my
>> guess about the hotter temp.. But these 2 variations of the glaze can
>> show up in the same firing pretty close to each other! It could be
>> that it's purely a temperature issue, with the crystals forming as
>> the glaze gets fired hotter. OR it could be that the glaze gets
>> mottled when appled thicker...What do you think?
>>
>> I've been selling this glaze on vases, etc and revelling in the
>> variation: check out the left hand vase in the pic on the page noted
>> above. It's truly a ZINGER.
>> BUT I have a wedding registry for red dinnerware, so by August I need
>> to understand how to get more consistency for a set of plates....
>> Jennifer, planning many more tests and appreciating John's book,
>> since I have more tools for testing productively....
>>
>>
>>
>> *****************************
>> Jennifer Boyer
>> Thistle Hill Pottery
>> Montpelier, VT
>> http://thistlehillpottery.com
>> *****************************
>>
>> _____________________________________________________________________
>> _________
>> 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.
>
>
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Lee Love on fri 18 may 07
On 5/17/07, Jennifer Boyer wrote:
> This web page has some pix of a Khaki Red glaze I'm using based on
> the Anderson Ranch khaki in John Britt's stoneware glaze book:
>
> http://www.thistlehillpottery.com/teapots.html
Jennifer,
Taditional kaki (kaki means plum colored, not military
khaki) breaks dark when thin. As you can see on the thin coat on your
tiny teapot, it looks like an oilspot where thinnest.
Try keeping the glaze application at the appropriate
thickness. Check using the nail scratch method.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.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
Jennifer Boyer on fri 18 may 07
Huh?
(excuse me while I slap myself)
OK, ready for the brain to start functioning:
So is that why thick glaze is different from thin?: The alumina and
silica in the clay are altering the chemistry of the thin layer, but
a thicker layer overwhelms the clay body's influence?
How had I never thought in those terms in all these years? Go figure.
But it makes so much sense.
I have been working on the thickness issue with this glaze all along
and my next batch of tests will explore the limits of how thin I need
to go since John Britt said it will go too orange when the glaze gets
really thin.
Thanks Dave!
Jennifer
On May 17, 2007, at 2:58 PM, Dave Finkelnburg wrote:
> Jennifer,
> I have not tested this particular glaze, nor
> investigated iron reds exhaustively, but in my
> experience with them I think you have most of the
> variables sorted out. I would add glaze thickness as
> a possible contributor. I would expect a thicker
> glaze coat to be more likely to appear as the glaze on
> the left since it will, in general, have less alumina
> and silica relative to flux.
> Good potting!
> Dave Finkelnburg
>
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Lee Love on fri 18 may 07
Jennifer ,
Here are some examples of the original Mashiko kaki:
http://mashikopots.blogspot.com/2007/03/kaki-resist-jomon-inlay-and-reeve-green.html
tinyurl if the above is broken: http://tinyurl.com/2qn6md
Click on the images to see a larger version. You will
notice, anywhere the glaze is thin, it looses the kaki color and
breaks black or mottled.
One way to make tenmoku is by adding 20% ash to Kaki and it
become black instead of red or brown.
Traditionally, Kaki is put over a clear feldspatic glaze.
This helps the color too but promotes breaking at the edges. It also
lends itself to "window" decoration with wax resist.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.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
Jennifer Boyer on fri 18 may 07
The teapots are oil spot and persimmon, but at least with the oil
spot the most spotty affect happened where the glaze was thickest..
My kaki tests are breaking dark where thick. So a thin glaze
application is looking like the direction I need to go in for my kaki
tests.
Jennifer
>
> Jennifer,
>
> Taditional kaki (kaki means plum colored, not military
> khaki) breaks dark when thin. As you can see on the thin coat on your
> tiny teapot, it looks like an oilspot where thinnest.
>
> Try keeping the glaze application at the appropriate
> thickness. Check using the nail scratch method.
>
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
David Beumee on fri 18 may 07
" My soak at the end is easy to do in oxidation since I'm stalling the kiln,
> but I'm glad to have your input and will try a more oxidizing
> atmosphere at the end. You don't think it has anything to do with
> over or under firing?"
Hi Jennifer,
The arbiter is always the cones, so keep watching them during the soak. Stop the firing when you're at the cone you want, meaning if you get there too quickly, start the soak earlier the next firing. I have a brick kiln which generates an amazing amount of radient heat, so I have to start the soak at cone 8 down to keep cone 11 from flattening, even though I'm turning down the burners to put the kiln in oxidation.
"I know that one critical issue with a high iron glaze is that iron
oxide fluxes more when reduced, so if you stay in oxidation you lower
the melting temp of the glaze."
Just the opposite. Iron is a flux in a reducing atmosphere, lowering the melting point of the glaze. Keeping the atmosphere in neutral or oxidation would keep the iron from becoming a flux, therefore raising the maturing temperature of the glaze.
"I also think that if you do reduce the
> glaze and it gets glossy there may be more of a tendency for the
> glaze to produce what look to me like crystalline structures."
From the photos in your post, your results look identical to my own, even though I use Val's Tomato Red and reduce the glaze. I've never considered the result glossy in the same sense of a clear glaze on porcelain. I'm astonished that you're getting the results that you are, firing in neutral or oxidation, as I always thought reduction and then reoxidation of this type of glaze was needed to reveal its color. it's an amazing testament to the versatility of this type of glaze.
Thanks very much for the compliment!
David Beumee
www.davidbeumee.com
Lafayette, CO
>
-------------- Original message ----------------------
From: Jennifer Boyer
>
> Hi David,
> As to oxidation, I fire my kiln in oxidation or neutral atmosphere. I
> try to stay under -.10 on my oxyprobe. This varies and sometimes I
> go as far as -.20, but I try not to as I have a white glaze that I
> try to keep from getting speckly(now, now, no eye rolling!). My soak
> at the end is easy to do in oxidation since I'm stalling the kiln,
> but I'm glad to have your input and will try a more oxidizing
> atmosphere at the end. You don't think it has anything to do with
> over or under firing?
>
> I know that one critical issue with a high iron glaze is that iron
> oxide fluxes more when reduced, so if you stay in oxidation you lower
> the melting temp of the glaze. I also think that if you do reduce the
> glaze and it gets glossy there may be more of a tendency for the
> glaze to produce what look to me like crystalline structures.
>
> Looks like I have a number of factors to consider!
> Jennifer
> PS You make gorgeous pots! And through modesty you don't include your
> web site in your posts?
> Check it out everyone: http://www.davidbeumee.com/
>
> On May 17, 2007, at 1:04 PM, claybuds@att.net wrote:
>
> > Hi Jennifer,
> > In the photo of your tests above the photo of the vases, the
> > mottling is on the test on the left of the photo, and also the vase
> > to the right of the lower "2 vases" photo.
> > I have used Val's Tomato Red, the recipe just to the right of the
> > Anderson Ranch recipe in John Britt's book, page 74. Although I'm
> > not familiar with the Anderson Ranch recipe in my kiln, the result
> > looks identical to what can happen with Val's Tomato Red. John
> > Britt is no doubt correct that application thickness has alot to do
> > with the ability of the glaze to come out orange instead of the
> > mottled, "leopard spots." But my experience of fifteen years firing
> > Val's Tomato Red in reduction at cone 10 is that prolonged
> > reoxidation at the end of the firing is key to producing the orange
> > color. You say you soak 40 minutes when you reach temperature. Is
> > the soak in oxidation? My experience is that it takes time at top
> > temperature for black iron oxide to reoxidize into red iron oxide,
> > giving the orange color. 40 minutes of soak in straight oxidation
> > should be plenty to produce an all-over orange color.
> > Best of luck with your dinnerware order.
> >
> > David Beumee
> > Porcelain by David Beumee
> > Lafayette, CO
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > -------------- Original message ----------------------
> > From: Jennifer Boyer
> >>
> >> This web page has some pix of a Khaki Red glaze I'm using based on
> >> the Anderson Ranch khaki in John Britt's stoneware glaze book:
> >>
> >> http://www.thistlehillpottery.com/teapots.html
> >>
> >> I'm trying to figure out why this glaze looks different in these 2
> >> tests. My guess is that the left hand test fired hotter and also was
> >> soaked longer so that crystals formed. This mottling happens(I think)
> >> more in the area nearer to the flame path of the burners, hence my
> >> guess about the hotter temp.. But these 2 variations of the glaze can
> >> show up in the same firing pretty close to each other! It could be
> >> that it's purely a temperature issue, with the crystals forming as
> >> the glaze gets fired hotter. OR it could be that the glaze gets
> >> mottled when appled thicker...What do you think?
> >>
> >> I've been selling this glaze on vases, etc and revelling in the
> >> variation: check out the left hand vase in the pic on the page noted
> >> above. It's truly a ZINGER.
> >> BUT I have a wedding registry for red dinnerware, so by August I need
> >> to understand how to get more consistency for a set of plates....
> >> Jennifer, planning many more tests and appreciating John's book,
> >> since I have more tools for testing productively....
> >>
> >>
> >>
> >> *****************************
> >> Jennifer Boyer
> >> Thistle Hill Pottery
> >> Montpelier, VT
> >> http://thistlehillpottery.com
> >> *****************************
> >>
> >> _____________________________________________________________________
> >> _________
> >> 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.
> >
> >
>
> *****************************
> Jennifer Boyer
> Thistle Hill Pottery
> Montpelier, VT
> http://thistlehillpottery.com
> *****************************
>
> ______________________________________________________________________________
> 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.
Neal on fri 18 may 07
The latest issue of Ceramics Monthly (mine just
came this week) has an article about how cooling
rate affects an iron red glaze that's fired to
cone 6 in an electric kiln. I have been trying
out different cooling rates for one of my cone 6
glazes--and now have new ideas to test since
reading that article.
The article may give you ideas about things
you can try to achieve consistency in your
firings.
Neal O'Briant
____________________________________________________________________________________
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Jennifer Boyer on sat 19 may 07
HI David
>
> "I know that one critical issue with a high iron glaze is that iron
> oxide fluxes more when reduced, so if you stay in oxidation you lower
> the melting temp of the glaze."
>
> Just the opposite. Iron is a flux in a reducing atmosphere,
> lowering the melting point of the glaze. Keeping the atmosphere in
> neutral or oxidation would keep the iron from becoming a flux,
> therefore raising the maturing temperature of the glaze.
Oops, I understood but misstyped!
>
> "I also think that if you do reduce the
>> glaze and it gets glossy there may be more of a tendency for the
>> glaze to produce what look to me like crystalline structures."
Kim Wrote me this:
Hi Jennifer,
Has anyone mentioned perhaps the one with spots are
more in a reduction location?
It almost looks like carbon trapping from the digital
image. I don't know the recipe, but I doubt it has
Neph Sy in it like shinos.
Kim Overall
http://www.kimoverall.com
(I am staying below .2 on the oxyprobe, so reduction is minimal, but
I'm going to look more at what is going on in different parts of the
kiln)
Back to David:
> From the photos in your post, your results look identical to my
> own, even though I use Val's Tomato Red and reduce the glaze. I've
> never considered the result glossy in the same sense of a clear
> glaze on porcelain. I'm astonished that you're getting the results
> that you are, firing in neutral or oxidation, as I always thought
> reduction and then reoxidation of this type of glaze was needed to
> reveal its color. it's an amazing testament to the versatility of
> this type of glaze.
Well, in John Britt's wonderful "Complete Guide to High-Fire Glazes"
he suggests an oxidation atmosphere for kaki glazes (and oil spots as
well)and says that the glazes will be brown in reduction.
I've never really understood the ins and outs of reoxidation at the
end of a firing. It seems to me that ALL kilns go back into oxidation
when you turn them off. I know there are some permanent reduction
effects like copper reds that can handle the kiln being turned off!
And that glazes entrap these effects in the glossy melt. But I have
no idea why you and I would both be getting a nice red kaki, when you
are reducing with oxidation at the end, and I am oxidizing the whole
way...
Jennifer, wondering
>
> Thanks very much for the compliment!
>
> David Beumee
> www.davidbeumee.com
> Lafayette, CO
>>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> -------------- Original message ----------------------
> From: Jennifer Boyer
>>
>> Hi David,
>> As to oxidation, I fire my kiln in oxidation or neutral atmosphere. I
>> try to stay under -.10 on my oxyprobe. This varies and sometimes I
>> go as far as -.20, but I try not to as I have a white glaze that I
>> try to keep from getting speckly(now, now, no eye rolling!). My soak
>> at the end is easy to do in oxidation since I'm stalling the kiln,
>> but I'm glad to have your input and will try a more oxidizing
>> atmosphere at the end. You don't think it has anything to do with
>> over or under firing?
>>
>> I know that one critical issue with a high iron glaze is that iron
>> oxide fluxes more when reduced, so if you stay in oxidation you lower
>> the melting temp of the glaze. I also think that if you do reduce the
>> glaze and it gets glossy there may be more of a tendency for the
>> glaze to produce what look to me like crystalline structures.
>>
>> Looks like I have a number of factors to consider!
>> Jennifer
>> PS You make gorgeous pots! And through modesty you don't include your
>> web site in your posts?
>> Check it out everyone: http://www.davidbeumee.com/
>>
>> On May 17, 2007, at 1:04 PM, claybuds@att.net wrote:
>>
>>> Hi Jennifer,
>>> In the photo of your tests above the photo of the vases, the
>>> mottling is on the test on the left of the photo, and also the vase
>>> to the right of the lower "2 vases" photo.
>>> I have used Val's Tomato Red, the recipe just to the right of the
>>> Anderson Ranch recipe in John Britt's book, page 74. Although I'm
>>> not familiar with the Anderson Ranch recipe in my kiln, the result
>>> looks identical to what can happen with Val's Tomato Red. John
>>> Britt is no doubt correct that application thickness has alot to do
>>> with the ability of the glaze to come out orange instead of the
>>> mottled, "leopard spots." But my experience of fifteen years firing
>>> Val's Tomato Red in reduction at cone 10 is that prolonged
>>> reoxidation at the end of the firing is key to producing the orange
>>> color. You say you soak 40 minutes when you reach temperature. Is
>>> the soak in oxidation? My experience is that it takes time at top
>>> temperature for black iron oxide to reoxidize into red iron oxide,
>>> giving the orange color. 40 minutes of soak in straight oxidation
>>> should be plenty to produce an all-over orange color.
>>> Best of luck with your dinnerware order.
>>>
>>> David Beumee
>>> Porcelain by David Beumee
>>> Lafayette, CO
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> -------------- Original message ----------------------
>>> From: Jennifer Boyer
>>>>
>>>> This web page has some pix of a Khaki Red glaze I'm using based on
>>>> the Anderson Ranch khaki in John Britt's stoneware glaze book:
>>>>
>>>> http://www.thistlehillpottery.com/teapots.html
>>>>
>>>> I'm trying to figure out why this glaze looks different in these 2
>>>> tests. My guess is that the left hand test fired hotter and also
>>>> was
>>>> soaked longer so that crystals formed. This mottling happens(I
>>>> think)
>>>> more in the area nearer to the flame path of the burners, hence my
>>>> guess about the hotter temp.. But these 2 variations of the
>>>> glaze can
>>>> show up in the same firing pretty close to each other! It could be
>>>> that it's purely a temperature issue, with the crystals forming as
>>>> the glaze gets fired hotter. OR it could be that the glaze gets
>>>> mottled when appled thicker...What do you think?
>>>>
>>>> I've been selling this glaze on vases, etc and revelling in the
>>>> variation: check out the left hand vase in the pic on the page
>>>> noted
>>>> above. It's truly a ZINGER.
>>>> BUT I have a wedding registry for red dinnerware, so by August I
>>>> need
>>>> to understand how to get more consistency for a set of plates....
>>>> Jennifer, planning many more tests and appreciating John's book,
>>>> since I have more tools for testing productively....
>>>>
>>>>
>>>>
>>>> *****************************
>>>> Jennifer Boyer
>>>> Thistle Hill Pottery
>>>> Montpelier, VT
>>>> http://thistlehillpottery.com
>>>> *****************************
>>>>
>>>> ___________________________________________________________________
>>>> __
>>>> _________
>>>> Send postings to clayart@lsv.ceramics.org
>>>>
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>>>>
>>>> Moderator of the list is Mel Jacobson who may be reached at
>>>> melpots@pclink.com.
>>>
>>>
>>
>> *****************************
>> Jennifer Boyer
>> Thistle Hill Pottery
>> Montpelier, VT
>> http://thistlehillpottery.com
>> *****************************
>>
>> _____________________________________________________________________
>> _________
>> 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.
>
>
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Lee Love on sat 19 may 07
On 5/18/07, David Beumee wrote:
> I always thought reduction and then reoxidation of this type of glaze was needed to
>reveal its color. it's an amazing testament to the versatility of
this type of glaze.
The original kaki is fired in oxidation.
Jennifer, you might try my Reeve's Sythetic Kaki. It is not a finicky.
John Reeve's "synthetic" Mashiko Kaki (AK5) ^10:
OM4 11.5
china clay calc'd 11.3
Kona f 4 31.4
Bone Ash .5
Talc 5.2
Wollastonite 6.5
Silica 27.0
Spanish Iron 6.4
Ti02 .5
Mn02 .2
100.5%
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.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 sat 19 may 07
On 5/18/07, Jennifer Boyer wrote:
> The teapots are oil spot and persimmon, but at least with the oil
> spot the most spotty affect happened where the glaze was thickest..
> My kaki tests are breaking dark where thick. So a thin glaze
> application is looking like the direction I need to go in for my kaki
> tests.
In the photo, looking at the stamp, the kaki colored sample looks
like a thicker application. The mottled one looks thinner (you can
see the details of the stamp better.
I adjust the thickness of my glaze during glazes at least
3 or 4 times, starting glazing thin ware and adding water as I glaze
thicker ware. My teacher adjusts his glaze thickness 5 or 6 times
during glazing because his ash glaze is very sensitive to the
thickness of application. Before studying with him, I never change
a glaze according to the thickness of the ware. I also sponge ware
with water . It is another way to control glaze thickness.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.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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