David Gallagher on mon 23 may 05
Hello all, I'm new to the group. I've been making pots for about a
year and a half now. Any way, I have a question about carbon trapping
and its reltaionship to soda ash. The shino Im using is a Malcolm
Davis recipie reformulated to fire at ^8. I've used it for about 3
kiln loads now and made two different batches, one with a little more
soda ash than the other... about a %. The second batch seems to carbon
trap a good deal more than the other... the peices that got the best
reduction were a nice blackish green.
At least i think thats what happened. The other factor was that some
of the peices were glazed and on the shelf for a solid three weeks
before they went into the kiln.
So Im wondering if any one has some insight to weither if the carbon
trap is effected by the small increase in the soda ash or if the time
on the shelf exposed to the elements effect the results more, or both?
Or was it just the firing? Its not the body reduction, im sure (hehe
yeah ok) of that.. since the body reduction in one load was pitiful
and the other was very good.
Oh the other thing, which is the new experiment... In a giddy bout of
self expression I grabbed some black copper oxide and just kind of
winged it on a couple of the pots... well, it came out with this
wonderfull red in the areas where it was thin (this is on very heavily
glazed pots double or tripple dipped, but the glaze was mixed
thin) ... so the question is, take an atomizer or straw with a fine
screen blow the powdered chemical on the pot (which seems mightly
unhealthy for me and those around me) or try and add it to the glaze
formula, and if so would any one have a recomendation of the percetage
to as a starting point? obviously this will take some testing and
time though. any way... glad to be here
David
Hank Murrow on mon 23 may 05
On May 23, 2005, at 11:03 AM, David Gallagher wrote:
> I have a question about carbon trapping
> and its reltaionship to soda ash. The shino Im using is a Malcolm
> Davis recipie reformulated to fire at ^8. I've used it for about 3
> kiln loads now and made two different batches, one with a little more
> soda ash than the other... about a %. The second batch seems to carbon
> trap a good deal more than the other... the peices that got the best
> reduction were a nice blackish green.
> At least i think thats what happened. The other factor was that some
> of the peices were glazed and on the shelf for a solid three weeks
> before they went into the kiln.
> So Im wondering if any one has some insight to weither if the carbon
> trap is effected by the small increase in the soda ash or if the time
> on the shelf exposed to the elements effect the results more, or both?
> Or was it just the firing? Its not the body reduction, im sure (hehe
> yeah ok) of that.. since the body reduction in one load was pitiful
> and the other was very good.
Dear David;
I am no expert on soda ash shinos (do a lot of no-soda ash shino
though). However, a note or two would be in order. After glazing, the
soluble soda ash will migrate to the surface of the pot as it dries. If
you rub this effluent off the pot, you will get less trapping. Of
course, you could mask areas of the piece to prevent evaporation at
those places. then you will get more and less trapping. You could glaze
and stack right away to let the piece evaporate in the kiln, whether
you were to fire right away or later. anyway, some ruminations you
might consider..........
Cheers, Hank
www.murrow.biz/hank
Kathy McDonald on tue 24 may 05
I have been doing some work with Malcolm Davis
shino.
Hank's advice about masking might yeild some results for you.
I find that two things affect the amount of carbon trapping that
i get.
1) the timing and amount of reduction, I think it works best when reduced
early in the firing.
2) the length of time between mixing and application of the glaze. I
haven't been very scientific about this
but I find that if the glaze sits for a long period of time in the bucket
(ie:more than month) the carbon trapping
is less than when it is applied soon after mixing. I also screen the glaze
prior to each use.
I also apply hot wax over portions of the glaze to get more carbon trapping.
There are some pictures of the preliminary results of this here:
http://photobucket.com/albums/y130/claylady/
Y
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Hank Murrow
Sent: Monday, May 23, 2005 7:22 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Carbon Trapping Question
On May 23, 2005, at 11:03 AM, David Gallagher wrote:
> I have a question about carbon trapping
> and its reltaionship to soda ash. The shino Im using is a Malcolm
> Davis recipie reformulated to fire at ^8. I've used it for about 3
> kiln loads now and made two different batches, one with a little more
> soda ash than the other... about a %. The second batch seems to carbon
> trap a good deal more than the other... the peices that got the best
> reduction were a nice blackish green.
> At least i think thats what happened. The other factor was that some
> of the peices were glazed and on the shelf for a solid three weeks
> before they went into the kiln.
> So Im wondering if any one has some insight to weither if the carbon
> trap is effected by the small increase in the soda ash or if the time
> on the shelf exposed to the elements effect the results more, or both?
> Or was it just the firing? Its not the body reduction, im sure (hehe
> yeah ok) of that.. since the body reduction in one load was pitiful
> and the other was very good.
Dear David;
I am no expert on soda ash shinos (do a lot of no-soda ash shino
though). However, a note or two would be in order. After glazing, the
soluble soda ash will migrate to the surface of the pot as it dries. If
you rub this effluent off the pot, you will get less trapping. Of
course, you could mask areas of the piece to prevent evaporation at
those places. then you will get more and less trapping. You could glaze
and stack right away to let the piece evaporate in the kiln, whether
you were to fire right away or later. anyway, some ruminations you
might consider..........
Cheers, Hank
www.murrow.biz/hank
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Lee Love on tue 24 may 05
David Gallagher wrote:
>At least i think thats what happened. The other factor was that some
>of the peices were glazed and on the shelf for a solid three weeks
>before they went into the kiln.
>
>
David, I have found that fast drying causes more carbon trapping. For
example, I have glazed, washed the glaze off, and then reglazed, and put
the pot into the kiln while it is still wet so it fast dried in the kiln
and this is when I get the most carbon trapping.
Also, if you wax-resist on top of the glaze, you will not have
carbon-trapping where you put the resist down, because it stops the
glaze evaportation where the resist is. So speed of evaporation is a factor.
>glazed pots double or tripple dipped, but the glaze was mixed
>thin) ... so the question is, take an atomizer or straw with a fine
>screen blow the powdered chemical on the pot (which seems mightly
>
>
Would a seive used to sprinkle the oxide over the pot be easier? Wear a
mask and do it outside.
>unhealthy for me and those around me) or try and add it to the glaze
>formula, and if so would any one have a recomendation of the percetage
>to as a starting point? obviously this will take some testing and
>time though. any way... glad to be here
>
Try different amounts, a lineblend. I have never done it, but some
people also sprinkle wood ash on their pots by tapping a screen over the
pot to sprinkle the ash. It leaves dark spots on shino.
--
李 Lee Love 大
愛 鱗
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft
"With Humans it's what's here (he points to his heart) that makes the difference. If you don't have it in the heart, nothing you make will make a difference." ~~Bernard Leach~~ (As told to Dean Schwarz)
David Gallagher on tue 24 may 05
Hank and Kathy
Thanks this is helpfull,
Kathy: I've used wax as well to get the orangeish accents your getting too. Its a great little tool, interestingly we changed wax and I got the exact opposite results... clear and lighter spots. This was wax with colorant it. Why the one with the colorant would act as a resist.. I just don't have any explination for. I like you pots by the way.
I had a couple that really carbon trapped... I mean blackish. It was really interesting.
I think you may be right about the amount of time in the bucket though.... I had similar results.
Hank... thanks for the masking idea. That could be alot of fun to play with. Unfortuatley I fire at a school and usually dont get to load the kiln, so I can't just load after I glaze. (I'm drooling at the though of that right now)
Kathy McDonald wrote:
I have been doing some work with Malcolm Davis
shino.
Hank's advice about masking might yeild some results for you.
I find that two things affect the amount of carbon trapping that
i get.
1) the timing and amount of reduction, I think it works best when reduced
early in the firing.
2) the length of time between mixing and application of the glaze. I
haven't been very scientific about this
but I find that if the glaze sits for a long period of time in the bucket
(ie:more than month) the carbon trapping
is less than when it is applied soon after mixing. I also screen the glaze
prior to each use.
I also apply hot wax over portions of the glaze to get more carbon trapping.
There are some pictures of the preliminary results of this here:
http://photobucket.com/albums/y130/claylady/
Y
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Hank Murrow
Sent: Monday, May 23, 2005 7:22 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Carbon Trapping Question
On May 23, 2005, at 11:03 AM, David Gallagher wrote:
> I have a question about carbon trapping
> and its reltaionship to soda ash. The shino Im using is a Malcolm
> Davis recipie reformulated to fire at ^8. I've used it for about 3
> kiln loads now and made two different batches, one with a little more
> soda ash than the other... about a %. The second batch seems to carbon
> trap a good deal more than the other... the peices that got the best
> reduction were a nice blackish green.
> At least i think thats what happened. The other factor was that some
> of the peices were glazed and on the shelf for a solid three weeks
> before they went into the kiln.
> So Im wondering if any one has some insight to weither if the carbon
> trap is effected by the small increase in the soda ash or if the time
> on the shelf exposed to the elements effect the results more, or both?
> Or was it just the firing? Its not the body reduction, im sure (hehe
> yeah ok) of that.. since the body reduction in one load was pitiful
> and the other was very good.
Dear David;
I am no expert on soda ash shinos (do a lot of no-soda ash shino
though). However, a note or two would be in order. After glazing, the
soluble soda ash will migrate to the surface of the pot as it dries. If
you rub this effluent off the pot, you will get less trapping. Of
course, you could mask areas of the piece to prevent evaporation at
those places. then you will get more and less trapping. You could glaze
and stack right away to let the piece evaporate in the kiln, whether
you were to fire right away or later. anyway, some ruminations you
might consider..........
Cheers, Hank
www.murrow.biz/hank
____________________________________________________________________________
__
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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Dave Finkelnburg on tue 24 may 05
Kathy,
While I don't doubt you are observing this in your work, the last time I heard Malcolm Davis comment on this he felt he saw NO problem with age of "American" Shino glaze in the bucket. He said then he often stored all his Shino glazes for six months in the bucket, and that when he needed more he just added to what was already in a bucket, without regard to age of the mixed glaze already present.
Good carbon trapping!
Dave Finkelnburg
Kathy McDonald wrote:
I haven't been very scientific about this
but I find that if the glaze sits for a long period of time in the bucket
(ie:more than month) the carbon trapping
is less than when it is applied soon after mixing.
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David Gallagher on wed 25 may 05
Hey Dave,
I don't know if you could call this a problem.... its just a difference. What I've seen is the longer its in the bucket the more it looks like Malcolm's things, but I think my eyes are playing tricks. I'm really thinking that the whole thing has to do with glaze thickness and reduction more than time in the bucket though, the more Im looking at things. thanks
Dave Finkelnburg wrote:
Kathy,
While I don't doubt you are observing this in your work, the last time I heard Malcolm Davis comment on this he felt he saw NO problem with age of "American" Shino glaze in the bucket. He said then he often stored all his Shino glazes for six months in the bucket, and that when he needed more he just added to what was already in a bucket, without regard to age of the mixed glaze already present.
Good carbon trapping!
Dave Finkelnburg
Kathy McDonald
wrote:
I haven't been very scientific about this
but I find that if the glaze sits for a long period of time in the bucket
(ie:more than month) the carbon trapping
is less than when it is applied soon after mixing.
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Liz Willoughby on wed 25 may 05
Hello David,
A few tips on carbon trapping.
>Hello all, I'm new to the group. I've been making pots for about a
>year and a half now. Any way, I have a question about carbon trapping
>and its reltaionship to soda ash. The shino Im using is a Malcolm
>Davis recipie reformulated to fire at ^8. I've used it for about 3
>kiln loads now and made two different batches, one with a little more
>soda ash than the other... about a %. The second batch seems to carbon
>trap a good deal more than the other... the peices that got the best
>reduction were a nice blackish green.
You get green black when there is too much soda ash. Malcolm calls
this snotty green!, but if you like it that is fine......
>At least i think thats what happened. The other factor was that some
>of the peices were glazed and on the shelf for a solid three weeks
>before they went into the kiln.
I have glazed pieces and left them on the shelf, and I honestly find
that I get better carbon trapping when I glaze one day before, or the
day of stacking the kiln. I think also that it all depends on how
long your pilots are on, (that will also have an effect on the salts
coming to the surface in various patterns, and where your pieces are
placed in the kiln. So, it is important to always have tests in all
over the place to try and locate your "sweet spots".
Some people have had success with copper reds over shino. It is
something that really hasn't interested me, so I haven't tried it. I
would say forget the atomizer and just use copper brush strokes, or
use a copper red glaze over the shino, that works too.
>
>Oh the other thing, which is the new experiment... In a giddy bout of
>self expression I grabbed some black copper oxide and just kind of
>winged it on a couple of the pots... well, it came out with this
>wonderfull red in the areas where it was thin (this is on very heavily
>glazed pots double or tripple dipped, but the glaze was mixed
>thin) ... so the question is, take an atomizer or straw with a fine
>screen blow the powdered chemical on the pot (which seems mightly
>unhealthy for me and those around me) or try and add it to the glaze
>formula, and if so would any one have a recomendation of the percetage
>to as a starting point? obviously this will take some testing and
>time though. any way... glad to be here
>David
David, there is lots in the archives about shinos. The trouble is,
that it is not a glaze that is easy, and just when you think you have
it licked it will throw you a curve ball. I always add new glaze to
old, Malcolm does too.
Best of luck,
Meticky Liz from Grafton, Ontario, Canada.
It is such a beautiful day out. Perfect weather, sunny, warm, lilacs
almost ready to burst in a riot of color.
I am going off clayart for a few days to attend the Fusion
Conference. You guys be good. Listen to Lili.
Rod Wuetherick on wed 25 may 05
> I don't know if you could call this a problem.... its just a
difference. What I've seen is the longer its in the bucket the more it >
looks like Malcolm's things, but I think my eyes are playing tricks. I'm
really thinking that the whole thing has to do with glaze > thickness and
reduction more than time in the bucket though, the more Im looking at
things. thanks
Actually the longer it is in the bucket does make a difference. Neph Sye is
slightly soluable and also if you mix and glaze and your shino is a trapping
variety with soda ash then the soda ash takes some time to go into solution.
When I mix/test shinos I always add the soda ash after it has been dissolved
in boiling water. This way I minimize what seems to be those creeping
changes.
Another thing about trapping shinos that I'm surprised that no one has
mentioned. Bisque - what cone do you bisque at? This makes an enourmous
difference. If you have fired enough shinos and have taken good notes one
take this simple fact hits you like a ton of bricks and you ask yourself ,
"why didn't I think of that?"
Some folks say when using shino on procelain you should wipe the porcelain
down before glazing? Why? Simple when you think about it if the bisque is a
little damp less soluable soda gets sucked into the body and therefore less
is available to precipitate to the surface later on. When using a trapping
shino on procelain I bisque to 03 believe it or not. If I go cooler then I
have to start wiping down the damn bisque. I don't have time for that so I
just bisque higher.
So if you have two clay bodies and your shino works wonderfully on one and
sucks on the other try doing a porosity test on the two bisque pieces - or
maybe just feel your bisque up a little and figure out which is "softer" and
depending on which works and which doesn't adjust your bisque accordingly.
Anyways enough rambling the above couple mentions are two things that I have
found over the years of firing thousands of carbon trapped shinos are two
variables that for some seem to make a shino a mysterious uncontrollable
monster. Once you figure these two really simple observations into your
paractice you can tame the shino beast into something a little less
unctrollable and get more of the results you are looking for.
I could be wrong but I think when one adds "new shino" to the old you are in
essense just watering down the old shino. If you work your soluables into
the picture from the onset you can get consistent results from the top of
the bucket to the bottome. I make 50 Kilogram batches of Shino at a time -
never had a problem. Of course there was that little problem 2 years ago
when I ran out of the soda ash I had been using for 5 years.
Never liked using anhydrous soda ash for my shinos. I prefer to buy a
washing soda that has been sprayed with a surfactant during processing.
Makes all the difference in the world for my shino recipes.
peace,
Rod
David Gallagher on thu 26 may 05
Thanks Liz,
Im going to start begging my teacher to let me load and fire the kiln soon. Funny, he chucks my 6'4 self into the wood kiln to load, but the gas kiln he likes to do. The funny thing is that I like the curve balls that the shino throws, consistency kinda bores me. I would rather have surprises and disappointments than knowing whats going happen every single time. at least in the reduction kiln. any way, thanks for the tips.
Liz Willoughby wrote:
Hello David,
A few tips on carbon trapping.
>Hello all, I'm new to the group. I've been making pots for about a
>year and a half now. Any way, I have a question about carbon trapping
>and its reltaionship to soda ash. The shino Im using is a Malcolm
>Davis recipie reformulated to fire at ^8. I've used it for about 3
>kiln loads now and made two different batches, one with a little more
>soda ash than the other... about a %. The second batch seems to carbon
>trap a good deal more than the other... the peices that got the best
>reduction were a nice blackish green.
You get green black when there is too much soda ash. Malcolm calls
this snotty green!, but if you like it that is fine......
>At least i think thats what happened. The other factor was that some
>of the peices were glazed and on the shelf for a solid three weeks
>before they went into the kiln.
I have glazed pieces and left them on the shelf, and I honestly find
that I get better carbon trapping when I glaze one day before, or the
day of stacking the kiln. I think also that it all depends on how
long your pilots are on, (that will also have an effect on the salts
coming to the surface in various patterns, and where your pieces are
placed in the kiln. So, it is important to always have tests in all
over the place to try and locate your "sweet spots".
Some people have had success with copper reds over shino. It is
something that really hasn't interested me, so I haven't tried it. I
would say forget the atomizer and just use copper brush strokes, or
use a copper red glaze over the shino, that works too.
>
>Oh the other thing, which is the new experiment... In a giddy bout of
>self expression I grabbed some black copper oxide and just kind of
>winged it on a couple of the pots... well, it came out with this
>wonderfull red in the areas where it was thin (this is on very heavily
>glazed pots double or tripple dipped, but the glaze was mixed
>thin) ... so the question is, take an atomizer or straw with a fine
>screen blow the powdered chemical on the pot (which seems mightly
>unhealthy for me and those around me) or try and add it to the glaze
>formula, and if so would any one have a recomendation of the percetage
>to as a starting point? obviously this will take some testing and
>time though. any way... glad to be here
>David
David, there is lots in the archives about shinos. The trouble is,
that it is not a glaze that is easy, and just when you think you have
it licked it will throw you a curve ball. I always add new glaze to
old, Malcolm does too.
Best of luck,
Meticky Liz from Grafton, Ontario, Canada.
It is such a beautiful day out. Perfect weather, sunny, warm, lilacs
almost ready to burst in a riot of color.
I am going off clayart for a few days to attend the Fusion
Conference. You guys be good. Listen to Lili.
______________________________________________________________________________
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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