Sue Leabu on tue 25 feb 03
Hello everyone,
A lurker here.... have looked through the archives for anything related to
burning out carbon-trapping because of too much heat. Didn't find anything,
so I'd love to hear any ideas/opinions regarding this. TIA!
A friend and I are just starting to experiment with carbon-trap glazes
(yes, we both love a challenge!).This was our second load of shino. Firing
a small (20 cf) gas kiln --new to both of us-- so that complicates the
learning curve because we haven't gotten a good handle on the kiln itself
yet. But we aren't letting that be a barrier!
First load a few weeks ago, fired in strong reduction starting at cone 010
through cone 10. Too much reduction. Lots of black pots. Too much black for
our tastes. Looking for salmon, peach, and white and carbon trapping.
Second firing, started very heavy reduction at cone 010 again, kept it
there for 90 minutes, then changed the atmosphere to light reduction till
cone 9 went. Increased the reduction to medium, but not quite as strong as
the body reduction phase. Soaked the kiln in this atmosphere for 90
minutes. From the spy hole, it looked like we had a small hook on cone 11
(which we were using as the guard), till we opened the kiln last night to
find that cone 11 had dropped in a twisted motion (?) and was really laying
up against a brick. (AARG!) From closer inspection of the cone packs and
other witness cones, we are fairly certain we were probably at or over cone
12. We oxidized the kiln for 10 minutes at the end of the firing, then shut
it down.
The results from this second load are pretty white and bland, especially
pots that were in the middle of the kiln shelves. Did get trapping on pots
that were on the outside edges of shelves, but it looks like we burned it
out of the pots in the middle. Is that possible? My friend's opinion is
that shinos can take the heat of cone 11, but sustaining that temp (or
more) could burn the carbon trapped earlier back out. I'm not so sure, and
think that maybe we lightened up the atmosphere too much after the body
reduction. (We don't have any oxygen probe to use.)
Thanks for any thoughts or guidance!
Sue in Kalamazoo, MI
clennell on wed 26 feb 03
>
> The results from this second load are pretty white and bland, especially
> pots that were in the middle of the kiln shelves. Did get trapping on pots
> that were on the outside edges of shelves, but it looks like we burned it
> out of the pots in the middle. Is that possible? My friend's opinion is
> that shinos can take the heat of cone 11, but sustaining that temp (or
> more) could burn the carbon trapped earlier back out. I'm not so sure, and
> think that maybe we lightened up the atmosphere too much after the body
> reduction. (We don't have any oxygen probe to use.)
>
> Thanks for any thoughts or guidance!
>
> Sue in Kalamazoo, MI
>
Sue: I just looked at our log and we have fired 105 firings of carbon trap
shino in the past 3 1/2 years. That's burnout! Wondering where the money
all went????????
I liked your approach to the first firing. to stop getting so much black we
use slips. Interestingly the carbon trapping doesn't seem to happen where
the slips are. so in effect go for the black but mask out areas with slips
that will give you your peaches, oranges, and different colours like blue or
red whatever your colour preference.
A white slip gives a lovely peach colour under CT shino.
If you don't build in some kind of safe guard then you are betting the bank
on a perfect firing. Our use of slips insures us of a saleable product. the
article curated by Malcolm Davis in Studio Potter has lots of good stuff in
it. there are so many variables to consider.
Look to Liz W and Hank (I don't sleep at night) M for some excellent
guidance.
cheers,
Tony
Liz Willoughby on wed 26 feb 03
Hello Sue in Kalamazoo, (couldn't resist, it rhymes so well)
Tony C. suggested that I might be able to help you out. First thing
that you have to understand about carbon-trap shinos is that it is a
very fickle glaze. I have mentioned before that I can have pots side
by side and they are entirely different. Orange, spotted, white,
peach, grey, and on.....
Also, shino's can take it hot. And I do not know if the carbon can be
burned out in the end, but I suspect not.
This is what I do.
Go into reduction at C/012, keep it in heavy reduction for 1-2 hours.
In my kiln (Bailey 24/18, forced air burners, propane fired), when I
go into reduction the temperature shoots up. I think that during
this time, carbon is trapped and the glaze is sealed over the carbon
trapping. I ease up on the reduction, but never go into light
reduction. (I fire by eye, smell, cones, pyrometer, and the look of
the flame in the cage). I try to keep the kiln climbing at around 40
degrees C an hour. It slows down at the end. When my cone 10 is at
2 0'clock I turn the kiln off, and close everything up. I do not
crash cool at the end or go into a period of oxidation. I also have
tenmokus and celadons in there and they are fine. The middle and
back of my kiln fire hotter, a good cone 11, and sometimes too,
probably a 12.
Get the back issues of Clay Times with Pete Pinnell's series of
articles on shino, and also the June issue of Studio Potter, Malcolm
Davis invited some carbon trappers to submit articles for this issue
and there is some good information and recipes to try.
The areas by the flue and on the top shelf are good areas for
carbon-trapping, in my kiln.
I have also been getting good results by dipping and then lightly
spraying with the shino.
If the glaze is too thick it will be white. Thinner it is more peach
or orange. And of course it depends on the claybody you use. I use
porcelain.
If you search the archives, there is lots of info there too.
Best of luck, Meticky Liz
p.s. I think you are right Sue.
>
>
>First load a few weeks ago, fired in strong reduction starting at cone 010
>through cone 10. Too much reduction. Lots of black pots. Too much black for
>our tastes. Looking for salmon, peach, and white and carbon trapping.
>
>The results from this second load are pretty white and bland, especially
>pots that were in the middle of the kiln shelves. Did get trapping on pots
>that were on the outside edges of shelves, but it looks like we burned it
>out of the pots in the middle. Is that possible? My friend's opinion is
>that shinos can take the heat of cone 11, but sustaining that temp (or
>more) could burn the carbon trapped earlier back out. I'm not so sure, and
>think that maybe we lightened up the atmosphere too much after the body
>reduction. (We don't have any oxygen probe to use.)
>
>Thanks for any thoughts or guidance!
>
>Sue in Kalamazoo, MI
Liz Willoughby
RR 1
2903 Shelter Valley Rd.
Grafton, On.
Canada
K0K 2G0
e-mail lizwill@phc.igs.net
Sue Leabu on wed 26 feb 03
Hi Tony,
Thanks for your thoughts. 105 shino firings! I'd bet that's burnout! But,
ya gotta love 'em though. Since this was only my second attempt (in gas
anyway), I'm still excited and intrigued. Will keep plugging away at it.
I appreciate your slip idea. I probably should have mentioned that we are
firing all white bodies right now: B-mix, Standard 182 White Stoneware, a
homemade porcelain (non-grolleg), and another homemade porcelaneous body
that has a just touch of redart in the recipe, used in an anagama. Shinos
on it in the wood kiln are just lovely. Using Malcolm Davis' shino (with
redart), Wirt's University Carbon Trap, a Warren MacKenzie recipe, and
Judith Duff's Gold. Also testing lots of others, just cuz.
So, that first firing was white bodies and (mostly) black pots. Enough
carbon trapping for four full loads, if only we could just magically
sprinkle it over the pots and have it stick.
Somehow between these two attempts we managed to find both ends of the
spectrum, and need to figure out where the middle is. Everything's got to
be somewhere! Next attempt at locating will be next week.
Thanks again!
Sue in Kalamazoo, MI
On Wed, 26 Feb 2003 16:48:57 -0500, clennell wrote:
>Sue: I just looked at our log and we have fired 105 firings of carbon trap
>shino in the past 3 1/2 years. That's burnout! Wondering where the money
>all went????????
>I liked your approach to the first firing. to stop getting so much black we
>use slips. Interestingly the carbon trapping doesn't seem to happen where
>the slips are. so in effect go for the black but mask out areas with slips
>that will give you your peaches, oranges, and different colours like blue
or
>red whatever your colour preference.
>A white slip gives a lovely peach colour under CT shino.
>If you don't build in some kind of safe guard then you are betting the bank
>on a perfect firing. Our use of slips insures us of a saleable product. the
>article curated by Malcolm Davis in Studio Potter has lots of good stuff in
>it. there are so many variables to consider.
>Look to Liz W and Hank (I don't sleep at night) M for some excellent
>guidance.
>cheers,
>Tony
>
>___________________________________________________________________________
___
>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.
Ilene Mahler on thu 27 feb 03
I fired some tiles in shino in a communal kiln the reduction was not there
Can I refire the tiles in the next load and will they reduce.. what do I
have to reglaze.. add iron or just throw away 50 tiles to finish my kitchen
backsplash..anxious Ilene in cold cold conn...hoping the plane really leaves
for Calif on Fiday the 7th
----- Original Message -----
From: "Liz Willoughby"
To:
Sent: Wednesday, February 26, 2003 4:26 PM
Subject: Re: Carbon trapping burn out?
> Hello Sue in Kalamazoo, (couldn't resist, it rhymes so well)
> Tony C. suggested that I might be able to help you out. First thing
> that you have to understand about carbon-trap shinos is that it is a
> very fickle glaze. I have mentioned before that I can have pots side
> by side and they are entirely different. Orange, spotted, white,
> peach, grey, and on.....
> Also, shino's can take it hot. And I do not know if the carbon can be
> burned out in the end, but I suspect not.
>
> This is what I do.
> Go into reduction at C/012, keep it in heavy reduction for 1-2 hours.
> In my kiln (Bailey 24/18, forced air burners, propane fired), when I
> go into reduction the temperature shoots up. I think that during
> this time, carbon is trapped and the glaze is sealed over the carbon
> trapping. I ease up on the reduction, but never go into light
> reduction. (I fire by eye, smell, cones, pyrometer, and the look of
> the flame in the cage). I try to keep the kiln climbing at around 40
> degrees C an hour. It slows down at the end. When my cone 10 is at
> 2 0'clock I turn the kiln off, and close everything up. I do not
> crash cool at the end or go into a period of oxidation. I also have
> tenmokus and celadons in there and they are fine. The middle and
> back of my kiln fire hotter, a good cone 11, and sometimes too,
> probably a 12.
> Get the back issues of Clay Times with Pete Pinnell's series of
> articles on shino, and also the June issue of Studio Potter, Malcolm
> Davis invited some carbon trappers to submit articles for this issue
> and there is some good information and recipes to try.
> The areas by the flue and on the top shelf are good areas for
> carbon-trapping, in my kiln.
> I have also been getting good results by dipping and then lightly
> spraying with the shino.
> If the glaze is too thick it will be white. Thinner it is more peach
> or orange. And of course it depends on the claybody you use. I use
> porcelain.
> If you search the archives, there is lots of info there too.
> Best of luck, Meticky Liz
> p.s. I think you are right Sue.
> >
> >
> >First load a few weeks ago, fired in strong reduction starting at cone
010
> >through cone 10. Too much reduction. Lots of black pots. Too much black
for
> >our tastes. Looking for salmon, peach, and white and carbon trapping.
> >
> >The results from this second load are pretty white and bland, especially
> >pots that were in the middle of the kiln shelves. Did get trapping on
pots
> >that were on the outside edges of shelves, but it looks like we burned it
> >out of the pots in the middle. Is that possible? My friend's opinion is
> >that shinos can take the heat of cone 11, but sustaining that temp (or
> >more) could burn the carbon trapped earlier back out. I'm not so sure,
and
> >think that maybe we lightened up the atmosphere too much after the body
> >reduction. (We don't have any oxygen probe to use.)
> >
> >Thanks for any thoughts or guidance!
> >
> >Sue in Kalamazoo, MI
>
> Liz Willoughby
> RR 1
> 2903 Shelter Valley Rd.
> Grafton, On.
> Canada
> K0K 2G0
> e-mail lizwill@phc.igs.net
>
>
____________________________________________________________________________
__
> 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.
Liz Willoughby on thu 27 feb 03
Sue, there is something that I forgot to say about too dark, or muddy
shinos. I collect those pots and put them in the electric kiln. I
fire them up to 1950 F, and soak them for 1 1/2 to 2 hours. They
come out lustrous. Some of the carbon does burn out, not a lot, but
there is more color (gold/orange), more depth. They really look
good. First I tried 1920 F, then 1930 F, but that really did not
work, they had more color, but were crazed badly, and felt like there
was a skin on them.
It is worth the effort. On my electric kiln the 04 bisque was not
high enough, thought that I could get away with just firing them with
the bisque, but they needed a slightly higher temperature. I use
porcelain.
I also quite often put them back in the glaze firing. Some of the
carbon does burn out. Not a lot, and I have found that they never
get darker from fresh carbon trapping.
Like Tony, I too, candle, but only for a few hours, and put my
burners on low overnight, start turning up my burners at 6 am in the
morning.
Like Tony, I also glaze my pots the day of or the day before I stack.
Depends how many I have. But I do find that if the glaze is too
thick, it is white, too thin it is matt. It is that perfect
application that seems to matter. Which is difficult with shino,
because of the soda ash, the glaze always appears thicker than it is.
Like Tony, I also sieve the glaze before using, and when I mix up a
new batch I add it to the old, and sieve it all together. The
sprinkled ash helps, especially if there is no carbon trapping.
Meticky Liz
Going off clayart for the week-end, and so sick of winter! Can hardly
wait to get to San Diego and some nice weather. Mel you are gettin'
some tea leaves!!!
>
>
>So, that first firing was white bodies and (mostly) black pots. Enough
>carbon trapping for four full loads, if only we could just magically
>sprinkle it over the pots and have it stick.
>
>Somehow between these two attempts we managed to find both ends of the
>spectrum, and need to figure out where the middle is. Everything's got to
>be somewhere! Next attempt at locating will be next week.
>
>Thanks again!
>
Sue in Kalamazoo, MI
Liz Willoughby
RR 1
2903 Shelter Valley Rd.
Grafton, On.
Canada
K0K 2G0
e-mail lizwill@phc.igs.net
MarjB on fri 28 feb 03
Morning Ilene
Dissolve some soda ash in water (warm) and brush on tiles. Vary the
thickness and cover only some areas of the tiles, to avoid a homogenous
surface. It is a fragile surface, so that may be a problem if others are
loading them into kiln. If your next firing has early reduction the soda ash
will give you the ct that is missing. Placement in the load will also have
an effect. MarjB (ps - check that the edges/underside of tiles did not
pick up any of the soda ash)
Liz Willoughby on fri 28 feb 03
Ilene, I have found that flat plates often don't catch the carbon
trap. And reglazing them with shino didn't help much either. You
could reglaze (I would spray) and then sprinkle very lightly some ash
on the glaze, for speckles. I also reglazed a plate once using a
brush loaded with tenmoku and brushed it on, fairly thick. People
thought it was carbon trapped. I would first experiment.
Off to London, Ontario now. Liz
>I fired some tiles in shino in a communal kiln the reduction was not there
>Can I refire the tiles in the next load and will they reduce.. what do I
>have to reglaze.. add iron or just throw away 50 tiles to finish my kitchen
>backsplash..anxious Ilene in cold cold conn...hoping the plane really leaves
>for Calif on Fiday the 7th
Liz Willoughby
RR 1
2903 Shelter Valley Rd.
Grafton, On.
Canada
K0K 2G0
e-mail lizwill@phc.igs.net
Sue Leabu on fri 28 feb 03
On Wed, 26 Feb 2003 17:26:06 -0400, Liz Willoughby
wrote:
>Hello Sue in Kalamazoo, (couldn't resist, it rhymes so well)
Hi Liz,
Ya know, the really humorous part is that my last name (Leabu) also rhymes
with Sue and Kalamazoo. :o)
Thanks for the info on your firing schedule and all the tips. I really
think we lost the carbon trapping early in the firing due to the
environment, not at the end with the excess heat. That's just what makes
sense to me.Also, in all the archive and other reading I've done, haven't
ever heard of shino not being able to take the heat, and have had some nice
ones come out of anagama firings in hot zones. Anyway...
I have the Pinnell articles, the Studio Potter issue from last year and
1992, the "American Shino" book, so lots of imagery and ideas. Will keep me
going for quite some time, I suspect. I know that working with shino can be
maddening, but the rewards are so sweet when you can get them. Will try
refiring some of my very black pots in my electric kiln, as you suggested.
I refired a couple of them in a regular glaze load (10R) at the art center
where I'm firing, but they didn't improve much. They certainly didn't need
any more reduction, that's for sure.
Am anxious to try again. Next firing scheduled on March 8. Crossing fingers!
Sue in Kalamazoo
>Tony C. suggested that I might be able to help you out. First thing
>that you have to understand about carbon-trap shinos is that it is a
>very fickle glaze. I have mentioned before that I can have pots side
>by side and they are entirely different. Orange, spotted, white,
>peach, grey, and on.....
>Also, shino's can take it hot. And I do not know if the carbon can be
>burned out in the end, but I suspect not.
>
>This is what I do.
>Go into reduction at C/012, keep it in heavy reduction for 1-2 hours.
>In my kiln (Bailey 24/18, forced air burners, propane fired), when I
>go into reduction the temperature shoots up. I think that during
>this time, carbon is trapped and the glaze is sealed over the carbon
>trapping. I ease up on the reduction, but never go into light
>reduction. (I fire by eye, smell, cones, pyrometer, and the look of
>the flame in the cage). I try to keep the kiln climbing at around 40
>degrees C an hour. It slows down at the end. When my cone 10 is at
>2 0'clock I turn the kiln off, and close everything up. I do not
>crash cool at the end or go into a period of oxidation. I also have
>tenmokus and celadons in there and they are fine. The middle and
>back of my kiln fire hotter, a good cone 11, and sometimes too,
>probably a 12.
>Get the back issues of Clay Times with Pete Pinnell's series of
>articles on shino, and also the June issue of Studio Potter, Malcolm
>Davis invited some carbon trappers to submit articles for this issue
>and there is some good information and recipes to try.
>The areas by the flue and on the top shelf are good areas for
>carbon-trapping, in my kiln.
>I have also been getting good results by dipping and then lightly
>spraying with the shino.
>If the glaze is too thick it will be white. Thinner it is more peach
>or orange. And of course it depends on the claybody you use. I use
>porcelain.
>If you search the archives, there is lots of info there too.
>Best of luck, Meticky Liz
>p.s. I think you are right Sue.
>Liz Willoughby
>RR 1
>2903 Shelter Valley Rd.
>Grafton, On.
>Canada
>K0K 2G0
>e-mail lizwill@phc.igs.net
>
>___________________________________________________________________________
___
>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.
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