Liz Willoughby on tue 24 nov 98
Continuing on the shino thread, I'm curious to know how people generally
fire their shinos.
What cone or temp. do you go into reduction?
How long and how heavy is your body reduction?
Much smoke ? during this time?
Do you continue in reduction all the way to the end? or go into neutral ?
after the body reduction? Or go back and forth?
Or do you oxidize at the end of the firing?
Would appreciate hearing how others fire their shinos. I'm going to figure
this thing out yet, (with everyone's help, I hope!)
Just reapplied ITC 296 A to the inside of my kiln. Still think that it
helps induce the carbon trapping and crystals that I aim for.
Thanks a bunch, Liz
Liz Willoughby
2903 Shelter Valley Rd.
R.R.#1
Grafton, Ontario
Canada. K0K 2G0
e-mail lizwill@phc.igs.ca
Dannon Rhudy on tue 24 nov 98
curious to know how people generally
>fire their shinos.
Hi, Liz. I go into body reduction at cone 010,
and then keep the kiln in light reduction for the
whole rest of the time.
Body reduction is from 30-45 minutes, depends
on my schedule and if I get distracted...I never,
repeat NEVER have smoke coming out of the kiln
during normal firing. I don't see any real point in
it, and it does not necessarily indicate reduction.
As to oxidizing at the end of the firing...as soon as
the gas is off the atmosphere re-oxidizes. If I am
in a hurry, I will crash cool to about 1750, then close it
up tight to finish.
If the kiln load is essentially shinos and other glazes
that do well in strong reduction, I will sometimes at the
end of the firing put a few pieces of wood into the kiln,
(and at that point of course I DO have smoke coming
out), close the damper, wait perhaps fifteen minutes or
so, open the damper for a few minutes to get the last
of the smoke out, then shut it down. Shinos seem to respond
well, lots of carbon trapping. Sometimes more than I had
in mind, in fact. But generally satisfactory.
Regards,
Dannon Rhudy
Donn Buchfinck on wed 25 nov 98
One of the tricks about shino is that the soda ash in the glaze is what
induces carbon trapping
so if you glaze the pot, then stick in into the kiln, and fire the kiln,
sometimes the soda ash does not have a chance to come to the surface of the
glaze. Thus trapping the carbon.
the trick to do is glaze the pot and let it sit over night so the water with
the soda ash can dry and deposit on the surface of the glaze.
If you do not believe me that this is what causes the carbon trapping, take a
glazed pot with shino inside and out, take some hot wax and paint a design on
the pot, re glaze the inside of the pot, not the outside. Let sit overnight
and then fire the pot. In an updraft kiln put the shinos in the top of the
kiln.
there was this potter in Iowa named Jerry Kessler who used to glaze his pots
then stick them out in the cold to freeze then he would load the kiln and
fire, this way it would drive the water to the surface of the pot and get
these funky designs.
another thing if the pot is dry and you pick in up you can leave fingerprints,
because by touching a dry glazed shino pot you can brush off the soda ash.
do body reduction at 014, this sounds low but the glaze seals over at 012,
even if the kiln is not even start the body reduction. Keep the kiln in
reduction all the way up.
now if you want some great black carbon just reduce the kiln like hell for 30
minutes at the end, black smoke and all coming out of the kiln. This
crashes the temperature so get it in a fast neutral atmosphere and take it up
again for 30 minutes after the heavy reduction. This help seal over any
bubbles in the glaze.
now I know that people say no smoke but some of the best shinos came from Ken
Ferguson and he fires his kiln like an old time coal burning train. He musta
done something right.
good luck
Donn Buchfinck
San Francisco
Craig Martell on thu 26 nov 98
Hello Liz:
Actually, I just fire the usual schedule and hope that this sets well with
shino, and whatever else is in the kiln.
I do a 12-13 hour firing from stone cold to cone 10 flat and soak at 10 for
about a half hour before shut down. I start reduction at cone 06 and
maintain reduction to the end of the firing. My oxyprobe readings are:
..07 at cone 06 and I leave the kiln alone and let the reduction lessen
naturally as the temp advances. At cone 5, the oxy usually reads about .06
and I leave this until cone 8 is down and then I maintain a reading of .65
to the end of the firing. At that temp, .65 is considered a medium
reduction value.
I'm not a real avid carbon trapper and pursue it passively. If it happens,
great, if not, oh well! What I want out of the shinos is a warm, friendly,
fire color. Red and hot orange. Since I do mostly porcelain, I need some
iron bearing clay in the glaze for this, or I'll use an iron slip under the
shino for color. Iron slips are nice because you can carve through them to
the white clay and get some nice variation in the work. But you were asking
about firing! I saw some nice Japanese shino pots at the V&A in London
last spring that had a white slip on a dark body and there was a nice carved
design through the slip.
There is a firing schedule that the Japanese have used to make the fire
color shinos in gas kilns. This is published in Ian Currie's book. It's so
long and protracted that I'd never consider it, but it's interesting to read
about this and may give some good ideas.
As for oxidizing, I agree with Dannon about the glaze oxidizing enough after
the kiln has shut down. There was a discussion on Ian Currie's glaze list
about shinos and it was mentioned that the fire color sometimes will not
develop until ambient temperature. Ian said that he opened a kiln at about
200 C, I think, and the shinos were grey and didn't turn red or orange until
they cooled to the outside temp.
As for crystals, I would think that it's a function of glaze chemistry and
slow cooling through certain temp ranges. The chemistry idea, is just that
certain minerals will form crystals when cooled slowly enough to devitrify
and if they are present in the glaze this may happen.
regards, Craig Martell in Oregon
Liz Willoughby on fri 27 nov 98
Hello Donn, Thanks for taking the time to answer my post about firing
shinos. (Also thanks to Dannon and Joyce.)
Malcolm Davis was here last Spring and I did a firing while he was here.
Lucky for me it was successful. He did some nice brush work on his freshly
dipped shino, which turned orange, and the area not waxed was quite dark
with carbon trapping. The inside was also orange. So. . .
>----------------------------Original message----------------------------
>If you do not believe me that this is what causes the carbon trapping, take a
>glazed pot with shino inside and out, take some hot wax and paint a design on
>the pot, re glaze the inside of the pot, not the outside. Let sit overnight
>and then fire the pot. In an updraft kiln put the shinos in the top of the
>kiln.
What are you saying here? After you reglaze the inside, where is the
carbon trapping?
>another thing if the pot is dry and you pick it up you can leave fingerprints,
>because by touching a dry glazed shino pot you can brush off the soda ash.
>do body reduction at 014, this sounds low but the glaze seals over at 012,
>even if the kiln is not even start the body reduction. Keep the kiln in
>reduction all the way up.
Yes, although I start my reduction at 012, usually get good carbon, and I
do continue in reduction all the way up. I have also picked up a shino mug,
still damp, and, after firing my fingermarks were white, with orange and
carbon around. Seems even compressing the glaze in the damp stage was
enough to cause a resist.
>now I know that people say no smoke but some of the best shinos came from Ken
>Ferguson and he fires his kiln like an old time coal burning train. He musta
>done something right.
There are so many different "kinds" of shino with different recipes.
Experienced potters get to know the glazes that they use, and the KILNS!!!
All different.
this is from Craig Martell a while back:
I really don't know much about carbon trapping. I can tell you what Warren
Mackenzie told me though. Well, first, I think that you have the concept
down pretty well. Carbon is deposited on the pieces early in the firing and
shinos are early fusers which trap the stuff before it can burn off. Warren
told me that he couldn't get carbon trap when he held reduction from low
temp on up. He said that after doing the low temp reduction for the clay,
if he oxidized or fired in neutral, the temp shot up very fast and THEN he
trapped carbon.
(now THATS'S interesting. I've never done that.)
Again, thanks for the info. Much appreciated. Liz
>good luck
>Donn Buchfinck
>San Francisco
Liz Willoughby
2903 Shelter Valley Rd.
R.R.#1
Grafton, Ontario
Canada. K0K 2G0
e-mail lizwill@phc.igs.ca
Craig Martell on sat 28 nov 98
>I start reduction at cone 06 and
>maintain reduction to the end of the firing. My oxyprobe readings are:
>.07 at cone 06 and I leave the kiln alone and let the reduction lessen
>naturally as the temp advances. At cone 5, the oxy usually reads about
>.06
Hi:
I slipped a cog again and the above oxyprobe readings are not correct. The
above should be: .7 at cone 06 and .6 at cone 5. The rest of the readings
I sent in the original post were correct.
I'll try to avoid this sort of tomfoolery in the future.
Craig Martell in Oregon
Karen Sullivan on tue 26 sep 00
I have had a range of results in my shino
my thinking is that it is a matter of when and how much reduction the glaze
experiences.
Could there be a discussion about firing strategies.
I fire cone 10-11
I reduce at 1000-1200 for body for about 5-10 minutes
Again I reduce at cone 1 - the clay body has not yet vitrified and it is an
effort to reduce, and not cause carbon coring
then I reduce at cone 5, because that is when the glaze is molten, for 5-10
minutes.
That is all the reduction I do, the kiln is set at a neutral setting for the
remaining bits.
My kiln is not huge, it is a 12 cu.ft. gas, perhaps I would conduct longer
reduction times if the kiln were a monster.
Basic to my thinking is that timely, short, light, quick reductions are
best.
Enlightenment would be appreciated.
Liz Willoughby on wed 27 sep 00
Hello Karen,
Yes, you are right about the "when and how much reduction" to use
when firing shinos. I start reducing heavily at cone 012, keep it
that way for an hour, and continue in moderate reduction to the end.
This is for Carbon Trapping Shinos.
There has been a lot of discussion about shinos in the past, try the
archives. Lots of info there, and good luck.
Liz
>I have had a range of results in my shino
>my thinking is that it is a matter of when and how much reduction the glaze
>experiences.
>Could there be a discussion about firing strategies.
>I fire cone 10-11
>I reduce at 1000-1200 for body for about 5-10 minutes
>Again I reduce at cone 1 - the clay body has not yet vitrified and it is an
>effort to reduce, and not cause carbon coring
>then I reduce at cone 5, because that is when the glaze is molten, for 5-10
>minutes.
>That is all the reduction I do, the kiln is set at a neutral setting for the
>remaining bits.
>My kiln is not huge, it is a 12 cu.ft. gas, perhaps I would conduct longer
>reduction times if the kiln were a monster.
>Basic to my thinking is that timely, short, light, quick reductions are
>best.
>Enlightenment would be appreciated.
Liz Willoughby
R.R. 1
2903 Shelter Valley Rd.
Grafton, Ontario
Canada. K0K 2G0
e-mail, lizwill@phc.igs.net
Ana Cláudia Schindler on wed 27 sep 00
Sorry, but what is shino? Maybe I know with other name because I'm
brasilian...
>From: Karen Sullivan
>Reply-To: Ceramic Arts Discussion List
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: firing shino
>Date: Tue, 26 Sep 2000 08:17:36 -0700
>
>I have had a range of results in my shino
>my thinking is that it is a matter of when and how much reduction the glaze
>experiences.
>Could there be a discussion about firing strategies.
>I fire cone 10-11
>I reduce at 1000-1200 for body for about 5-10 minutes
>Again I reduce at cone 1 - the clay body has not yet vitrified and it is an
>effort to reduce, and not cause carbon coring
>then I reduce at cone 5, because that is when the glaze is molten, for 5-10
>minutes.
>That is all the reduction I do, the kiln is set at a neutral setting for
>the
>remaining bits.
>My kiln is not huge, it is a 12 cu.ft. gas, perhaps I would conduct longer
>reduction times if the kiln were a monster.
>Basic to my thinking is that timely, short, light, quick reductions are
>best.
>Enlightenment would be appreciated.
>
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>
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Dave Finkelnburg on thu 24 mar 05
Robert,
You'll get lots of mail about this question. Carbon can be elusive in the kiln. There are several steps where you can lose it, if you ever have it in the first place. There's an excellent explanation of all this with Malcolm Davis' article in Studio Potter, I believe December '03. There's also lots in the archives.
Basically, you either never had soot deposited on the ware in the first place (it has to be there before the glaze melts to be "trapped") or you let the kiln into oxidation and burned up the soot before the glaze melted.
Good potting,
Dave Finkelnburg
Robert Fox wrote:
I recently fired a gas kiln with a few pieces glazed in a carbon trap
shino, but they came out of the kiln completly clear. Does someone know
what I did wrong? Thanks.
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Robert Fox on thu 24 mar 05
I recently fired a gas kiln with a few pieces glazed in a carbon trap
shino, but they came out of the kiln completly clear. Does someone know
what I did wrong? Thanks.
Rod Wuetherick on fri 25 mar 05
> I recently fired a gas kiln with a few pieces glazed in a carbon trap
> shino, but they came out of the kiln completly clear. Does someone know
> what I did wrong? Thanks.
Robert,
It would help if you included the recipe you used ;)
As far as a shino coming out completly clear. What do you mean by clear? No
trapping, translucent, etc.
If your shino was translucent and you mixed the recipe correctly I would
suspect that you applied way to thin. A Shino glaze likes to be applied
quite thick. Because Shino glazes predominately have twice the amount of
alumina than regular "well behaved" glazes you do not have to worry about
running.
If you are getting to much crawling if you apply think it is helpful to
calcine your china clay.
If you meant clear as in "no trapping" that is another story all together.
Most people when they start firing shino glazes don't reduce early enough.
In my experience as well a shino glaze prefers to be fired in an environment
where there is a fair amount of back pressure reducing secondary air. Really
the reduction would be obtained differently that say if you were firing a
celadon or copper red. John Britt in his book calls the phenomena streaming
I believe. With Shinos at least in my experience they like when the kiln is
in a "streaming" condition. Or perhaps more correctly I like the say carbon
trapped shinos look when they are in a heavily dampered/streaming
environment. If you did the same thing with copper red, celadon, etc. You
would very likely get unreduced areas on your pot.
On an oxy-probe I fire my shino at 6.6 - 7.6 depending on the amount of
trapping that I want. Though remember with shino how long they have sat also
play a part in the amount of trapping. I find shino that have an excess of
8-10% soda ash can be quite successfully fired in a glaze and burn scenario.
Whereas if the glaze is less that 8% or so it does seem to help them along a
bit if they have a 24-48 hour waiting period before fired.
As with shino your mileage will very. So many things to consider with this
troublesome glaze.
Good luck and send us that recipe of yours... Though I think if you meant
translucent you simply applied it to thin. The S.G of my shino is mixed to
1.5 - quite thick.
Peace,
Rod
Liz Willoughby on fri 25 mar 05
Hello Robert,
Shino recipes for carbon trap can contain 2 - 19 % of soda ash, so
if your recipe is at the lower end of the scale, you may want to
increase the soda ash. It is essential that you reduce early, around
cone 012, and keep it in heavy reduction for at least an hour. I
then ease up a bit, but continue in fairly heavy reduction throughout
the firing. I do not have an oxy probe so can not help you there. I
just make sure that I don't lose the reduction. The glazes melt
early, and as you create carbon in the atmosphere by reduction, it is
grasped by the glaze, seals over, and then you have your carbon trap.
There are always sweet spots for the carbon trapping. Mine is at the
top front, or middle front, although there are times when I have had
carbon trapping just about anywhere. It is a mystery sometimes, but
if you lust after those dots or halos, it is well worth the effort.
I would suggest putting tests everywhere in your kiln next to cone
packs to see where the carbon trapping is best for you.
If your claybody is stoneware or high in iron, your glaze will be
darker in color, or have more depth, if porcelain, it will be more
peach or white in color. Applied thinly it will be more orange,
applied more thickly it will be more white, and usually more carbon
trapping. Really thick and it will crawl.
Of course all this depends on your glaze recipe, of which there are hundreds.
It is a question of how much testing you want to do.
Ron Roy had a lecture at NCECA where he demonstrated how he created
the shino that he wanted by using INSIGHT, glaze calculation, because
for him, he wants to create his own glaze for his pots. So that is
another way to go, if you know what you want, and have a glaze
calculation program.
There is a lot of information in the archives.
Do you have Studio Potter, Vol. 21
#1? Good article in there on shinos by Jim Robinson.
Also a more recent Studio Potter, Vol 30 #2, has articles in it by
various potters, some with recipes, curated by Malcolm Davis.
Carbon Trap Glaze Addict otherwise known as Miticky Liz from Grafton,
Ontario, Canada
>I recently fired a gas kiln with a few pieces glazed in a carbon trap
>shino, but they came out of the kiln completly clear. Does someone know
>what I did wrong? Thanks.
Tony Ferguson on fri 25 mar 05
Robert,
Clear shino = oxidation or your burned off the reduction by oxidizing too fast. Start reducing around cone 010--even as early as 015. Looking in your kiln. If you can see everything clearly, you're probably oxidizing. If you can't see anything and flames are bursting out 6" - 8" from your peep hole = too much reduction. Find a happy balance. You want a flame out your peeps that is more than just licking (this is closer to neutral or very light reduction). A 2" to 4" flame ought to do it. It depends on your kiln, but try this. If you have an oxy probe, I think the good reduction is around .75 (but ask an oxyprobe xpert) I've only used them twice as a guide line to help out a friend. I am sure you will get many responses. Keep accurate records when you fire with everything you do and you will figure it out. Good skill.
Tony Ferguson
Dave Finkelnburg wrote:
Robert,
You'll get lots of mail about this question. Carbon can be elusive in the kiln. There are several steps where you can lose it, if you ever have it in the first place. There's an excellent explanation of all this with Malcolm Davis' article in Studio Potter, I believe December '03. There's also lots in the archives.
Basically, you either never had soot deposited on the ware in the first place (it has to be there before the glaze melts to be "trapped") or you let the kiln into oxidation and burned up the soot before the glaze melted.
Good potting,
Dave Finkelnburg
Robert Fox wrote:
I recently fired a gas kiln with a few pieces glazed in a carbon trap
shino, but they came out of the kiln completly clear. Does someone know
what I did wrong? Thanks.
---------------------------------
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Yahoo! Small Business - Try our new resources site!
______________________________________________________________________________
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You may look at the archives for the list or change your subscription
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Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Tony Ferguson
Artist & Educator
fergyart@yahoo.com
fergy@cpinternet.com
(218) 727-6339
http://www.aquariusartgallery.com
http://www.tonyferguson.net
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John Baymore on fri 25 mar 05
>I recently fired a gas kiln with a few pieces glazed in a carbon trap
>shino, but they came out of the kiln completly clear. Does someone know
>what I did wrong? Thanks.
Robert,
There is a short article on my website (originally published elsewhere)
that might be of help to you in understanding something about firing
shinos. About 1/2 way through it gets into the way that American shinos
work with their high content of soluble fluxes.....but likely it will make
more sense if you just read the whole thing from the start. Hope it helps.
Here's the address:
http://www.johnbaymore.com/moreglaz.html
best,
..................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
JBaymore@compuserve.com
http://www.JohnBaymore.com
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