Pam on wed 2 jun 04
A few days ago, I mixed my first batch of shino, namely Malcome (Davis)'s
Red Shino. The bucket of this glaze at the guild was down to just a couple
of inches, and my mentor wanted to glaze several large pieces. I decided
jump in and mix it so we could get his work glazed on a day I could be there
to help (and learn how to glaze pots that big!). I mixed my batch (12000
grams) in a new clean bucket, and kept it away from the older bucket of
shino, in case I screwed it up. My teacher looked at my batch and declared
it good, ie right color and consistency, it passed his "coat the finger"
test. So we went ahead and used it on two of his large pieces, and then a
bunch of my work. As the pieces dried, a white powdery film formed on the
outside of the pots, on top of the chocolate pudding colored glaze. I think
this is soda ash leaching to the surface. The glaze from the old bucket
doesn't do this. Did I do something wrong? I used warm water to dissolve
the soda ash when I was mixing, as it did not look like it would go through
the sieve otherwise. If I messed it up, my mentor is going to be an unhappy
man! Not to mention all of my stuff I shino-ed. I am hoping this is ok,
thinking back to Mayor Mel's article about black shino, and spraying
dissolved soda ash solution onto shinos in order to get more carbon
trapping. If this batch of mine produces lots of carbon trapping on those
large pieces, I will have a very happy mentor, and will be put in charge of
shino mixing LOL
Pam
pam@cresswells.com
Sue Leabu on wed 2 jun 04
On Wed, 2 Jun 2004 07:53:15 -0500, Pam wrote:
>As the pieces dried, a white powdery film formed on the
>outside of the pots, on top of the chocolate pudding colored glaze. I think
>this is soda ash leaching to the surface. The glaze from the old bucket
>doesn't do this. Did I do something wrong? I used warm water to dissolve
>the soda ash when I was mixing, as it did not look like it would go through
>the sieve otherwise.
Hi Pam,
The white powdery film is indeed the soda ash that is being deposited on
the surface of the pot as the water in the glaze evaporates. Remember that
soda ash is a soluable ingredient. It is dissolved in the water used to
make the glaze, and so it will show up on the surface when the glaze dries.
This is exactly what you want to see in a carbon-trap shino. Be careful to
not disturb the powdery surface once it appears, as any fingerprints can
show up on the fired piece.
The reason that the glaze in the old bucket didn't result in the filmy
surface is that the soda ash solution was probably reduced as pots were
glazed. I like to resieve shinos frequently, and add a fresh half-batch
when the bucket is half empty. That keeps the level of soda ash more
consistent. I also always dissolve the soda ash in very hot water first,
and then add the rest of the glaze materials to that solution adding more
water as needed to get the consistency I'm looking for. If by chance you
mix the glaze too thin, don't decant the excess water. You will be pouring
off the soda ash solution, which can result in less carbon trapping. Good
luck!
Sue
Kalamazoo, MI
sdr on wed 2 jun 04
......mixed my first batch of shino......
used it ..... As the pieces dried, a white powdery film formed
Did I do something wrong?......
No, you didn't do anything wrong. This often happens with
shino glazes, and especially ones that contain soda ash.
It migrates to the surface and crystalizes, makes a white
grainy surface. Makes for good carbon trapping.
regards
Dannon Rhudy
Dave Finkelnburg on wed 2 jun 04
Pam,
It sounds like you did things right with the glaze! :-)
I seriously question your observation that the "old" batch didn't cause
white scumming on pots. To prove this to yourself, you would need to glaze
two identical tiles, one in each batch, and observe them side by side as
they dry. I suspect you just didn't look so critically at the glazed pots
when you weren't the one stressing about whether the glaze batch was mixed
correctly!
I hope your carbon trap firing goes well,
Dave Finkelnburg
----- Original Message -----
From: "Pam"
Sent: Wednesday, June 02, 2004 6:53 AM
> A few days ago, I mixed my first batch of shino, namely Malcome (Davis)'s
> Red Shino..... As the pieces dried, a white powdery film formed on the
> outside of the pots, on top of the chocolate pudding colored glaze. I
think
> this is soda ash leaching to the surface. The glaze from the old bucket
> doesn't do this. Did I do something wrong? I used warm water to dissolve
> the soda ash when I was mixing, as it did not look like it would go
through
> the sieve otherwise.
Lee Love on wed 2 jun 04
Pam wrote:
>trapping. If this batch of mine produces lots of carbon trapping on those
>large pieces, I will have a very happy mentor, and will be put in charge of
>shino mixing LOL
>
>
Pam,
This is pretty normal in a new batch of shino, especially with
the amount of shino Davis uses. You may not have seen it in the old
batch, because as a batch of shino is used, it looses some of its solubles.
If you reduce early (cone 012) you should have a lot of carbon
trapping.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Liz Willoughby on wed 2 jun 04
Hello Pam,
You did nothing wrong. This is what always happens with a shino
glaze with soda ash. As the glaze dries and sits, the salts rise to
the surface of the applied glaze. If the work is glazed and left
where there is a breeze or fan, you can see the salts rise in those
areas faster.
Perhaps it was not noticeable on the old applied glaze, because:
1.) soda ash is soluble, and there might not have been much left in
the glaze bucket
2.) work was glazed and put in the kiln immediately, and not left out
to dry for hours, or days.
When mixing a new glaze, I always add it to the old. Sometimes it is
best too, to mix a shino glaze up a couple of weeks before you use
it, to make sure that the soda ash in the glaze is well dissolved.
Even if you dissolve it in hot water, and put it through a sieve.
I also use a variation of Malcolm's recipe, with a high soda ash 18%
in the glaze.
Hope you get lots of good carbon trapping.
Best,
Meticky Liz from Grafton Ontario, Canada (also a shino addict)
>A few days ago, I mixed my first batch of shino, namely Malcome (Davis)'s
>Red Shino. The bucket of this glaze at the guild was down to just a couple
>of inches, and my mentor wanted to glaze several large pieces. I decided
>jump in and mix it so we could get his work glazed on a day I could be there
>to help (and learn how to glaze pots that big!). I mixed my batch (12000
>grams) in a new clean bucket, and kept it away from the older bucket of
>shino, in case I screwed it up. My teacher looked at my batch and declared
>it good, ie right color and consistency, it passed his "coat the finger"
>test. So we went ahead and used it on two of his large pieces, and then a
>bunch of my work. As the pieces dried, a white powdery film formed on the
>outside of the pots, on top of the chocolate pudding colored glaze. I think
>this is soda ash leaching to the surface. The glaze from the old bucket
>doesn't do this. Did I do something wrong? I used warm water to dissolve
>the soda ash when I was mixing, as it did not look like it would go through
>the sieve otherwise. If I messed it up, my mentor is going to be an unhappy
>man! Not to mention all of my stuff I shino-ed. I am hoping this is ok,
>thinking back to Mayor Mel's article about black shino, and spraying
>dissolved soda ash solution onto shinos in order to get more carbon
>trapping. If this batch of mine produces lots of carbon trapping on those
>large pieces, I will have a very happy mentor, and will be put in charge of
>shino mixing LOL
>Pam
>pam@cresswells.com
--
Pam on wed 2 jun 04
whew, glad I did not mess up! Thanks all!
Pam
pam@cresswells.com
Paul Herman on wed 2 jun 04
Repost:
Hello Pam,
You did good! To get nice carbon trapping, the white powdery soda ash on
the surface (efflorescence) is what you need. Dissolving the soda in
warm water is exactly right.
In the old bucket of glaze, the soda ash content is reduced by use. I
think it goes something like this:
Each time you dip a piece in the bucket, the suspended solids are
deposited on the surface, and some water (containing dissolved soda ash)
is absorbed by the body. The bisque is sucking up water for the few
seconds it is submerged. As the bucket thickens you add water,
effectively diluting the solution. By the time you get to the bottom of
the bucket, you have removed a higher percentage of the solubles than of
the suspended particles.
I also use Malcolm's shino, but it's so high in soda ash (17%) that I
haven't noticed any lack of efflorescence toward the bottom of the tub.
The glaze is made up kind of thick, and pots are held under for a quick
three count. If the glaze was made thin, and the pieces held under for a
longer time, more soda would be absorbed.
Sounds to me like you should be made the chief shino mixer.
good glazing,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: Pam
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: mixing shinos question, soda ash film
>Date: Wed, Jun 2, 2004, 5:53 AM
>
> As the pieces dried, a white powdery film formed on the
> outside of the pots, on top of the chocolate pudding colored glaze. I think
> this is soda ash leaching to the surface. The glaze from the old bucket
> doesn't do this. Did I do something wrong? I used warm water to dissolve
> the soda ash when I was mixing, as it did not look like it would go through
> the sieve otherwise. If I messed it up, my mentor is going to be an unhappy
> man! Not to mention all of my stuff I shino-ed. I am hoping this is ok,
> thinking back to Mayor Mel's article about black shino, and spraying
> dissolved soda ash solution onto shinos in order to get more carbon
> trapping. If this batch of mine produces lots of carbon trapping on those
> large pieces, I will have a very happy mentor, and will be put in charge of
> shino mixing LOL
Christy Pines on wed 2 jun 04
What's interesting to me about this post is how it applies to other types of glazes and how knowing what's in that glaze, and what each ingredient is likely to do, is so important.
If I know that there is soda ash, and I know that soda ash is a water-soluable ingredient, and I know that as I use the glaze I may be depleting the quantity of soda ash left in the glaze, I can then understand why my results from the end-of-bucket glazing are different from my beginning-of-bucket results.
If I learn what parts of a glaze are likely to have these characteristics (soluablility), I'm more likely to pay attention to a glaze that is getting low in the bucket.
Right? Or not right? I don't know. I'm just beginning the glaze exploration, since the kiln is due in 3 weeks.
christy in connecticut, where the weather pretended to be wicked but was only just a tease this afternoon.
Paul Herman wrote:
In the old bucket of glaze, the soda ash content is reduced by use. I
think it goes something like this:
Each time you dip a piece in the bucket, the suspended solids are
deposited on the surface, and some water (containing dissolved soda ash)
is absorbed by the body. The bisque is sucking up water for the few
seconds it is submerged. As the bucket thickens you add water,
effectively diluting the solution. By the time you get to the bottom of
the bucket, you have removed a higher percentage of the solubles than of
the suspended particles.
Joseph Coniglio on fri 4 jun 04
This message string was extremely important for me!!
This is ClayArt at its best.
I'm a shino guy. I love to hear how people explain the soda ash.
This string had a combination of kindness, art, expertise, and a love
for the shino.
I was brought up on shino as my first real love. It is a staple
component of my glaze activity.
Shino is an adventure and the best advice I can offer you, that I have
not yet seen here is this:
You can set 4 pieces coated in shino, in the kiln at cone 10R get 4
different results in the same firing. BUT The moment you load a kiln
with nothing but shino ---watch out--- that's when the kiln god says
"gotcha!" And he/she better love you or your shafted!!! I've heard some
real hard luck stories of essentially having to toss a bad shino batch.
DO NOT BE ASHAMED TO PIECE MEAL YOUR SHINOS BY PLACING
ONLY A FEW IN YOUR FIRINGS A LITTLE AT AT TIME.
I heard even MD himself (out of West Virginia) fires only small test
batches in his 12 cube updraft.
This is what I call "Firing less (quantity), but firing (the kiln) more
often"
ALL THE BEST.
Thank you.
---------
Joe
Starting July 1st 2004:
Joseph Coniglio
Garnet Mesa Pottery
3249 1600 Road
Delta, CO 81416
Joe Coniglio
(914) 980-8788 US mobile
Lee Love on fri 4 jun 04
Christy Pines wrote:
>If I learn what parts of a glaze are likely to have these characteristics (soluablility), I'm more likely to pay attention to a glaze that is getting low in the bucket.
>
>Right? Or not right? I don't know. I'm just beginning the glaze exploration, since the kiln is due in 3 weeks.
>
Loosing solubles over time is a common effect in high soda ash
shinos and glazes that depend upon unwashed ash for fluxing.
Because I l scoop out the water on top of the glaze bucket
before I start glazing (to glaze thinner work with thicker glaze), I
always set the shino water aside, to be put back into the glaze when I
need to add water to glaze thicker work.
In the past, I have either added soda ash to an old bucket or
made sure I filled the bucket with a new batch before it got over half
used.
I am not a big fan of too much carbon trapping. Malcolm Davis
is just about the only person I know of that can use it to good
effect. It doesn't occur in Japanese shinos and is considered a glaze
or firing flaw (too much reduction at the wrong time.). That's why
here in Japan, I call the Wirt family of shinos carbon trap glaze,
instead of a shino.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Ron Roy on sat 5 jun 04
Hi Christy,
There is no doubt - the more you understand about your materials - the
easier problem solving becomes.
Some materials are completely water-soluable (like soda ash) and some partially
- like Neph Sy and lithium carb.
Having water-soluble ingrediants in a glaze is problematic - it is the
reason why water-soluble materials are not usually used in glazes.
The Hamer book has some of the information about materials - one of the few
book s that has that kind of information.
Out of the Earth Into the Fire by Mimi Obstler (published by The American
Ceramic Society) goes into great detail on most of the materials we use - I
recommend it highly.
RR
>What's interesting to me about this post is how it applies to other types
>of glazes and how knowing what's in that glaze, and what each ingredient
>is likely to do, is so important.
>
>If I know that there is soda ash, and I know that soda ash is a
>water-soluable ingredient, and I know that as I use the glaze I may be
>depleting the quantity of soda ash left in the glaze, I can then
>understand why my results from the end-of-bucket glazing are different
>from my beginning-of-bucket results.
>
>If I learn what parts of a glaze are likely to have these characteristics
>(soluablility), I'm more likely to pay attention to a glaze that is
>getting low in the bucket.
>
>Right? Or not right? I don't know. I'm just beginning the glaze
>exploration, since the kiln is due in 3 weeks.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Lee Love on sun 6 jun 04
Ron Roy wrote:
>Having water-soluble ingrediants in a glaze is problematic - it is the
>reason why water-soluble materials are not usually used in glazes.
>
Only in industry, is it a considered a problem. This is very
important for the creative person to understand.
On the otherhand, Potters have always made use of
solubles, especially in their woodash glazes.
What we have here is a good example of the difference
between the industrial mindset's need to control, and the artists use
of and cooperation with, variability of materials, processes, and firing.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Ron Roy on mon 7 jun 04
>Ron Roy wrote:
>
>>Having water-soluble ingredients in a glaze is problematic - it is the
>>reason why water-soluble materials are not usually used in glazes.
>>
>
> Only in industry, is it a considered a problem. This is very
>important for the creative person to understand.
> Lee
Not true,
Certain materials can make glazes settle out badly, flocculate glazes, flux
clays and create all kinds of problems.
Understanding our craft is much more than controlling what we do - it gives
us better understanding which leads to better problem solving and all kinds
of flexibility in creating our own work.
It's like the guy who once said on ClayArt - but I don't want stable glazes
- the answer is - if you know how to create stable glazes you know how to
make unstable glazes - it's just using what you know to get what you want.
Of course there will always be some who - once they know how to control -
cannot use that knowledge to get uncontrolled results. I suspect that many
more simply do not care to know and will use any excuse to not learn.
It does not matter where knowledge comes from - it is how you use it that
makes the difference.
To some - knowledge limits creativity - to others it is an indispensable
tool that enhances every aspect of their work.
RR
>Ron Roy wrote:
>
>>Having water-soluble ingrediants in a glaze is problematic - it is the
>>reason why water-soluble materials are not usually used in glazes.
>>
>
> Only in industry, is it a considered a problem. This is very
>important for the creative person to understand.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Gail Dapogny on mon 7 jun 04
And for anyone who is new to Clayart or to others who haven't yet
gotten to really know him, this is pure Ron Roy, always a voice of
wisdom, and the reason that so many of us love him.
Gail Dapogny in Ann Arbor
> Understanding our craft is much more than controlling what we do - it
> gives
> us better understanding which leads to better problem solving and all
> kinds
> of flexibility in creating our own work.
> ...
> It does not matter where knowledge comes from - it is how you use it
> that
> makes the difference.... To some - knowledge limits creativity - to
> others it is an indispensable
> tool that enhances every aspect of their work.
>
> RR
>
>
>
Lee Love on wed 9 jun 04
Ron you said:
>water-soluble materials are not usually used in glazes.
Most high fire traditional glazes have included ash, which includes soluble materials. Most naturally occurring non-industrial clays and stones contain some level of organics and solubles and these are what give them their special characteristics. Only in industrial materials, often air floated and killed to allow them to be "controlled", can we see a total absences of soluble materials. So your above statement maybe be true of your personal method, but is not true of potter specific materials that have been used throughout the ages.
For the modern potter, the Wirt family shino-type glazes
are the probably the most popular glazes in America that depend upon
solubles (soda ash) for the special effects of the glaze. Malcolm
Davis shinos could not exist without them. You just have to learn
from the glaze and adjust accordingly. Sometimes, we can learn from
the materials and the processes, if we don't demand industrial
control. On one hand, we have the grandeur of nature to be inspired
by. On the other hand, we have the Big Mac. ;-)
>Understanding our craft is much more than controlling what we do - it gives
>us better understanding which leads to better problem solving and all kinds
>of flexibility in creating our own work.
>
>
I recommend David Hendley's article in May Ceramics Monthly.
He describes a flexible way of approaching glazes which makes good use
of both industrial glaze calculation for industrial materials, and
line-blend and triaxial for potter specific materials, (like the
traditional use of ash, local clays and stones.) It is the flexible
method I use.
If you subscribe to CM, you can read the article here (to get your
login, put in your email address and the info will be sent to you, if
you are a subscriber.):
http://www.ceramicsmonthly.org/richcontent.asp
You can also see Judith Duff's article about firing the Train Kiln with
Mel. It is about process, and is in the current issue. It relates
to what we are talking about. There is also an article by Phil Rogers
(I highly recommend Phil's book on Ash Glazes) about Matsuzaki Ken. I
haven't read it yet.
I just read a great quote in the magazine The Log Book. You can find
more information about it here: http://homepage.eircom.net/~thelogbook
It is from Jack Troy's tribute to David Shaner. It talks about the
non-materialistic approach to art:
Work for the work's sake, sing or paint or carve.
The things thou loveth though the body starve.
Who works for glory misses off the goal
Who works for money, coins his very soul.
Work for the work's sake and maybe it shall be
These things will be added unto thee.
-- Kenyon Cox (*Painter
and Muralist, 1856-1919]*)
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Lee Love on wed 9 jun 04
Ron you said:
>water-soluble materials are not usually used in glazes.
Most high fire traditional glazes have included ash, which includes
soluble materials. Most naturally occurring non-industrial clays and
stones contain some level of organics and solubles and these are what
give them their special characteristics. Only in industrial
materials, often air floated and killed to allow them to be
"controlled", can we see a total absences of soluble materials. So
your above statement maybe be true of your personal method, but is not
true of potter specific materials that have been used throughout the ages.
For the modern potter, the Wirt family shino-type glazes
are the probably the most popular glazes in America that depend upon
solubles (soda ash) for the special effects of the glaze. Malcolm
Davis shinos could not exist without them. You just have to learn
from the glaze and adjust accordingly. Sometimes, we can learn from
the materials and the processes, if we don't demand industrial
control. On one hand, we have the grandeur of nature to be inspired
by. On the other hand, we have the Big Mac. ;-)
>Understanding our craft is much more than controlling what we do - it gives
>us better understanding which leads to better problem solving and all kinds
>of flexibility in creating our own work.
>
>
I recommend David Hendley's article in May Ceramics Monthly.
He describes a flexible way of approaching glazes which makes good use
of both industrial glaze calculation for industrial materials, and
line-blend and triaxial for potter specific materials, (like the
traditional use of ash, local clays and stones.) It is the flexible
method I use.
If you subscribe to CM, you can read the article here (to get your
login, put in your email address and the info will be sent to you, if
you are a subscriber.):
http://www.ceramicsmonthly.org/richcontent.asp
You can also see Judith Duff's article about firing the Train Kiln with
Mel. It is about process, and is in the current issue. It relates
to what we are talking about. There is also an article by Phil Rogers
(I highly recommend Phil's book on Ash Glazes) about Matsuzaki Ken. I
haven't read it yet.
I just read a great quote in the magazine The Log Book. You can find
more information about it here: http://homepage.eircom.net/~thelogbook
It is from Jack Troy's tribute to David Shaner. It talks about the
non-materialistic approach to art:
Work for the work's sake, sing or paint or carve.
The things thou loveth though the body starve.
Who works for glory misses off the goal
Who works for money, coins his very soul.
Work for the work's sake and maybe it shall be
These things will be added unto thee.
-- Kenyon Cox (*Painter
and Muralist, 1856-1919]*)
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Vince Pitelka on wed 9 jun 04
> Only in industry, is it a considered a problem. This is very
> important for the creative person to understand.
Lee -
Ron is certainly not infallible (almost, but not quite), but you do seem to
have the bad habit of contradicting him rather blatantly some times when it
is not warranted. Your statement above is perplexing, because OF COURSE it
is a problem for the studio potter. If you really take into consideration
the full effect of any soluble materials not only on the glaze, but on the
claybody as well, then it can be workable. But how many of us do that Lee?
A strong soluble flux like soda ash absorbed into the claybody does not all
migrate back to the surface during drying, and it will change the
vitrification properties of the claybody.
Shinos are a special case, because they seem to depend so heavily on the
soda ash, and so many of us love what they do, so we live with the problems
and he chemical imbalance that seems inherent in shinos. And of course ash
glazes are a special case as well. But those are the anomalies. What other
standard glazes types are there that use significant amounts of soluble
materials? I can think of the low-fire lithium glazes, like the popular
Jaquie Rice glazes. What else?
I am not being contrary. I really want to know. I thought about it and
couldn't come up with any other good examples, most likely because potters
DO try to avoid using soluble materials in glazes.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
John Britt on thu 10 jun 04
Lee,
How about we give Ron a break? We are all the emperor at sometime.
I think that for someone who has been as generous and persevering as Ron
has all these years, he deserves a break!
John Britt
John Britt on thu 10 jun 04
Vince,
You ask: "What other
standard glazes types are there that use significant amounts of soluble
materials? I can think of the low-fire lithium glazes, like the popular
Jaquie Rice glazes. What else?"
Actually, there are quite a few besides shinos. Anything with gerstley
borate (or its substitutes) like Cone 10 copper reds, Karen's Starshine,
cone 6 glazes (many use GB), ash glazes (with unwashed ash, and many other
glazes use small quantities of ash like celadons), VC turquoie Matte, many
Raku or low fire glazes with GB or with borax.
Hope that helps,
John Britt
www.johnbrittpottery.com
Jon Pacini on thu 10 jun 04
Hi Lee----Nice point regarding solubility. You replied--
Ron you said:
>water-soluble materials are not usually used in glazes.
Most high fire traditional glazes have included ash, which includes
soluble materials. Most naturally occurring non-industrial clays and stones
contain some level of organics and solubles and these are what give them
their special characteristics. Only in industrial materials, often air
floated and killed to allow them to be "controlled", can we see a total
absences of soluble materials. So your above statement maybe be true of
your personal method, but is not true of potter specific materials that have
been used throughout the ages.
I m not sure how Ron can make such a statement. Not only is Ash soluble, but
also most Alkaline minerals are soluble to an extent. Nephline Synite is a
commonly used glaze mineral and can solely deflocculate a porcelain slip
when used in large percentages. Gerstley Borate is a widely used glaze
ingredient and is notoriously soluble. Even commercial frits are somewhat
soluble, just try putting a borosilicate frit in a clay body and see how it
reacts, then you decide about the solubility of the materials we use.
Best regards
Jon Pacini
Clay Manager
Laguna Clay Co
Vince Pitelka on thu 10 jun 04
> Actually, there are quite a few besides shinos. Anything with gerstley
> borate (or its substitutes) like Cone 10 copper reds, Karen's Starshine,
> cone 6 glazes (many use GB), ash glazes (with unwashed ash, and many other
> glazes use small quantities of ash like celadons), VC turquoie Matte, many
> Raku or low fire glazes with GB or with borax.
John -
Good points. I hadn't really been thinking of Gerstley borate glazes,
because it is a slow release, and as a matter of practice most people use up
their high-GB glazes quickly for that reason. Borax is generally used only
in Raku glazes, and therefore is on a porous body and would have negligible
effect on body maturation. I should have been more specific, because I was
thinking of soluble materials that would directly effect vitrification,
which is only an issue on midrange and high-fire bodies. GB and neph sy
both release soluble alkalines into solution over time, but when we refer to
soluble glaze materials, I always think of things like borax and soda ash,
which immediately go into solution rather than suspension, and can seriously
affect body maturation (or more importantly, over-maturation) on midrange or
high-fired wares.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Lee Love on fri 11 jun 04
Jon Pacini wrote:
> Not only is Ash soluble, but
>also most Alkaline minerals are soluble to an extent. Nephline Synite is a
>commonly used glaze mineral and can solely deflocculate a porcelain slip
>when used in large percentages. Gerstley Borate is a widely used glaze
>ingredient and is notoriously soluble.
>
>
Jon, I am excited about trying non-soda ash shinos on clay bodies
that have some level of solubles in them. I was telling Bayard about
this today. He visited Matsuzaki's pottery yesterday. Matsuzaki
was not there, he is in Boston for his show at the Pucker. Was shown
around by one of the Deshis. Bayard was saying that Matsuzaki uses a
little clay in his shinos, with the feldspar.
I am going to try my hiratsu reformulation on my thixotropic
shigaraki clay. Will do a lineblend with kaolin too and maybe other
clays, to see if I can get some mattness in the hiratsu.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Pam on fri 11 jun 04
Hi, 'tis me again, back with results from my bucket of shino. The kiln with
my mentor's pots, and the test tiles was unloaded this AM, with some major
surprises. His pots were green. A matt, deep forest (chrome green for you
painters) with an orange peel texture. On the inside the colors were more as
expected, orange with gold luster, but blistered and crawling to an extreem.
Both large pieces are like this. Once we got over the shock, we both decided
that they are actually beautiful. There was another piece fired that looked
the same, matt green, and I am 99% sure this was glazed from the old bucket
of shino. To deepen the mystery, my test tiles, (new bucket, 50/50 blend,
and old bucket, came out just as expected, typical coloration. I have posted
a picture of them at http://www.cresswells.com/pots/shino.htm.
The old bucket yeilded no carbon trapping or metalic sheen. The 50/50 and
the fresh look nearly the same. I do not have a picture of the green pots
unfortunatly (not my pots). We are thinking that either the glaze was
over-fired, cooled too fast, or heated too fast. Any opinions?
mystified in shino land, pam
Roger Korn on fri 11 jun 04
I think Hank may wish to comment about shinos that are soda ash-free!
Roger, leaving AZ for OR on Monday
Vince wrote:
...
Shinos are a special case, because they seem to depend so heavily on the
soda ash
...
--
McKay Creek Ceramics
In OR: PO Box 436
North Plains, OR 97133
503-647-5464
In AZ: PO Box 463
Rimrock, AZ 86335
928-567-5699
Lee Love on fri 11 jun 04
Vince Pitelka wrote:
>
> Here was Ron's original statement that I disagreed with, with warrant,
> I believe:
>
>> water-soluble materials are not usually used in glazes.
>
Hi Vince,
Now, allow me to give you a practical example. As you might
know from experience, sometimes our public posts are inspired by
something written off-line. You know I pointed out David Hendley's
article in the May issue of Ceramics Monthly. Someone wrote me about
the usage of soda ash in once fired glazes that appears in David's
article. If you subscribe, look at expanded content, archived
articles, and you can read Hendley's article. It can be found here:
http://www.ceramicsmonthly.org/richcontent.asp
David knows the utility of water soluble material in once-fired
glazes, they assist in thickening the glaze for application to
leatherhard ware. Probably, the traditional once-firers did not have
to use soda ash, because of the solubles already present in their
natural materials:
Short quote:
"Thixotropy is the phenomenon whereby slips change their
fluidity, depending on whether they are agitated or left to rest,
becoming more fluid when stirred and more viscous when undisturbed.
Soda ash is my material of choice for making a slip that is
fluid with the addition of very little water (deflocculated) and will
set quickly when painted on a vertical surface (thixotropic)."
So, if a newbie is told that water soluble materials
are usually not used in glazes, and they are told this by someone who
is supposed to be a glaze expert, they might hesitate in using the
special abilities of these materials as described to use in Hendley's
article.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Lee Love on fri 11 jun 04
Vince Pitelka wrote:
>Ron is certainly not infallible
>
>
* Hehe.* You can say that again. I have always enjoyed Imperial types
strutting around with no clothes.
Here was Ron's original statement that I disagreed with, with warrant, I
believe:
> water-soluble materials are not usually used in glazes.
This is has not been true during the greater part
of the history of high fire glazes. For the most part, potter's high
fire glazes have always contain some amount of ash. When they don't
have ash, they frequently contain unrefined clay, feldspar and other
types of natural stones, which all contain some amount of organics and
solubles. (you should smell my shigaraki water bowl in the summer.
You'd swear it was a Detroit sewer. Reminds me of the Red Run sewer
drain on whose grassy banks we used to "cardboard sled" on in the summer.)
And shino seems to be just about the most popular
glaze for cone 10 reduction in N. America. It is incorrect to say
"Soluble materials are not USUALLY used in glazes."
Also, in lower temps, you frequently see the use of
gertsley borate or Nepheline Syenite, which both have a degree of
solubility. Remember our Dear Karl Platt talking about "Ghastly
Borate." (If you want to talk about folks who actually avoid water
soluble materials, talk to the Glass Man. ;-) ) And if you have
ever mixed up the 70/30 Neph Sye/Ball Clay shino, without soda ash,
you will see how it releases soluble sodium and can even carbon trap.
I had a kiln load of i 70/30 that is either all metallic or carbon
trapped from the solubles in Neph Sye. It contained no soda ash. Of
course, it is easier with my clays, because some of the solubles come
from the clay and not the glaze. I didn't realize this until my
recent single fire experiments.
We only think it is true in North America, because we are
primarily confined to using industrial refined materials.
>Shinos are a special case, because they seem to depend so heavily on the
>soda ash, and so many of us love what they do, so we live with the problems
>and he chemical imbalance that seems inherent in shinos. And of course ash
>glazes are a special case as well. But those are the anomalies. What other
>standard glazes types are there that use significant amounts of soluble
>materials? I can think of the low-fire lithium glazes, like the popular
>Jaquie Rice glazes. What else?
>
>
You, Like Ron, are being a little myopic. Not everyplace in
the world is like North `Merica. :-) Because I work
almost exclusively with natural materials and not industrially refined
materials, my clay and glazes all have some level of organic and
solubles in them. Almost all my glazes have ash in them (all but my
wirt shinos that have soda ash in them.) Because of the solubles in
my clay, they are thixotropic. Clay, especially shigaraki clay, may
seem hard in the bag, but if you slam it on the wheel head a couple
times, it becomes soft.
Actually, the natural solubles in Japanese clays might give
us some insight into their shinos. While they did not add solubles to
the shino glaze, there may have been solubles that entered the glaze
through the clay. Now, if we only understood glazes from you and
Ron's perspective, we my never have come to this insight! (I have
never heard this mentioned before!)
I guess I better quote myself again:
> Most high fire traditional glazes have included ash, which
> includes
> soluble materials. Most naturally occurring non-industrial clays and
> stones contain some level of organics and solubles and these are what
> give them their special characteristics. Only in industrial
> materials, often air floated and killed to allow them to be
> "controlled", can we see a total absences of soluble materials. So
> your above statement maybe be true of your personal method, but is not
> true of potter specific materials that have been used throughout the ages.
>I am not being contrary.
>
Oh yeah? ;-)
> I really want to know. I thought about it and
>couldn't come up with any other good examples, most likely because potters
>DO try to avoid using soluble materials in glazes
>
>
Only where and when you live Vince. Outside of industrial materials,
it is more difficult to avoid water soluble materials.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Lee Love on sat 12 jun 04
Pam wrote:
>a picture of them at http://www.cresswells.com/pots/shino.htm.
>The old bucket yeilded no carbon trapping or metalic sheen.
>
Pam,
Thanks for doing this for us!
One of the things I like to do in a new kiln is put
shino tests in them. Actually, I use two tests: one shino, that
tells me about early reduction and another of my copper/strontium
glaze, because it stays blue/green unless there is heavy
reduction. I make tests to create a grid inside the kiln: ideally
with a tile on each side of each level and one in the middle, adding up
to 5 tiles of each glaze per level. I like to do these sets of 5 in
a minimum three levels: bottom/middle/top. This gives you a grid
of both the temperature and atmospheric conditions throughout the
kiln. Can be an eye opener. Good project for students.
I want a kiln that fires at a variety of temps and
atmospheres. Industry demands uniformity and this misleads young
potters. But if the artist cooperates with the process, they can get
much more variety and also wonderful surprises at the interface of control.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Hank Murrow on sat 12 jun 04
> Vince wrote:...
> Shinos are a special case, because they seem to depend so heavily on
> the
> soda ash...
Then Roger Korn wrote:
> I think Hank may wish to comment about shinos that are soda ash-free!
And Hank replies that there is Shino and there is Shino.
Most American Shinos depend to a wide extent across the country on soda
ash for their qualities.
Mark Rhodes, Jim Robinson, and myself use glazes that do not use soda
ash, but rely on long firings and/or spodumene and/or oxidation soaks
in cooling to develop surfaces and colour that call to mind the
Momoyama-era shinos of Japan.
To quote the poet Rumi:
Let the Beauty you love be what you do.
There are hundreds of ways to kneel and kiss the Ground.
Cheers, Hank
www.murrow.biz/hank
Lee Love on sun 13 jun 04
Hank Murrow wrote:
>> Vince wrote:...
>> Shinos are a special case, because they seem to depend so heavily on
>> the
>> soda ash...
>
>
> Then Roger Korn wrote:
>
>> I think Hank may wish to comment about shinos that are soda ash-free!
>
>
> And Hank replies that there is Shino and there is Shino.
> Most American Shinos depend to a wide extent across the country on soda
> ash for their qualities.
The Wirt shinos use spodumene. This is where its use began actually.
Lithium is something not found in the original shinos.
Solubles also come from Neph Sye. I get carbon trapping from a glaze
that is 70% Neph Sye and 30% Gariome ball clay, with no soda ash
added. Another soluble used is salt. Jack Troy reports that
Currie picked up the use of salt in shinos from Taijimi Japan, where
they fire in gas for about 5 days.
> Mark Rhodes, Jim Robinson, and myself use glazes that do not use soda
> ash, but rely on long firings and/or spodumene and/or oxidation soaks
> in cooling to develop surfaces and colour that call to mind the
> Momoyama-era shinos of Japan.
Matsuzaki fires shinos for 7 days in his yohen kiln,
but much longer in his gas kiln. Most of the firing is done at a
lower temperature. The same is true of the Taijimi shinos. I am
guessing these folks could learn from Hank about the soaking in
oxidation in cool down and save trees, wood and time. :-)
> To quote the poet Rumi:
>
> Let the Beauty you love be what you do.
> There are hundreds of ways to kneel and kiss the Ground.
Rumi knows the grace of devotion.
As potters, we need not kneel to kiss the ground...
We pick it up and caress it in our hands....
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Lee Love on sun 13 jun 04
Hank Murrow wrote:
> Mark Rhodes, Jim Robinson, and myself use glazes that do not use soda
> ash, but rely on long firings and/or spodumene and/or oxidation soaks
> in cooling to develop surfaces and colour that call to mind the
> Momoyama-era shinos of Japan.
I just wanted to add. While all these shinos are wonderful in
their own way, none of them, IMHO, come near being like the original
shinos from Mino. This includes shinos in both Japan and America that
do not have soda ash or salt in them.
There is a diversity in the old shinos that are yet to be
rediscoved in our time. The new shinos are more stark and not as
nuanced as the old.
It presents us with a challenge and an opportunity to equal the
work done in the past. If we are not easily satisfied with what has
been done so far, someone will do it.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Liz Willoughby on sun 13 jun 04
Hello Pam,
I just had a look at your test tiles. I am wondering if the tiles
were placed side by side, and if you had more tiles glazed the same,
scattered throughout the kiln.
There are times when I too get that "green" from Malcolm's shino.
Malcolm has also had it in the past. Pete Pinnell wrote a series of
articles in Clay Times a couple of years ago about shino, and he did
mention that the "snotty green" was caused with a shino glaze
overloaded with soda ash. I think too, that if it was crawling and
blistering on the inside then the glaze was very thick. More soda
ash would migrate through to the outside, which might be the cause of
the overload of soda ash, and the green on the outside.
Malcolm's glaze usually does not crawl and blister, unless the clay
is very thin, and the glaze is heavily applied.
It is all a mystery! Pots side by side, same glaze can come out
looking entirely different. Usually thin promotes more orange, thick
more white with more carbon trapping, really thick, more crawling and
maybe more carbon trapping and maybe "snotty green" Malcolm's phrase.
Thanks for putting the tiles up.
Meticky Liz from Grafton, Ontario, Canada, where the weather is
gorgeous and the garden is becoming a riot of color, and the grass is
growing too fast.
>Hi, 'tis me again, back with results from my bucket of shino. The kiln with
>my mentor's pots, and the test tiles was unloaded this AM, with some major
>surprises. His pots were green. A matt, deep forest (chrome green for you
>painters) with an orange peel texture. On the inside the colors were more as
>expected, orange with gold luster, but blistered and crawling to an extreem.
>Both large pieces are like this. Once we got over the shock, we both decided
>that they are actually beautiful. There was another piece fired that looked
>the same, matt green, and I am 99% sure this was glazed from the old bucket
>of shino. To deepen the mystery, my test tiles, (new bucket, 50/50 blend,
>and old bucket, came out just as expected, typical coloration. I have posted
>a picture of them at http://www.cresswells.com/pots/shino.htm.
>The old bucket yeilded no carbon trapping or metalic sheen. The 50/50 and
>the fresh look nearly the same. I do not have a picture of the green pots
>unfortunatly (not my pots). We are thinking that either the glaze was
>over-fired, cooled too fast, or heated too fast. Any opinions?
>mystified in shino land, pam
Ron Roy on sun 13 jun 04
I have some questions for those that think there are no problems with using
solubles in glazes.
Why do most of the glazes used by potters not have solubles added?
Why is ash washed?
Why do we have frits?
Why do some glazes settle out badly?
Why do some glazes thicken over time?
Why do some clays bloom?
Why do some clays exhibit unusual fit problems when solubles are present in
glazes.
Why do some potters have problems with crystals forming in the glaze bucket?
RR
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Pam on sun 13 jun 04
Hi Liz,
yes, those three tiles were all lined up, sitting on the same shelf
with the infamous "green" pots. I did not have any others,
guess I should have done more. I noted that in this firing, there
were other pots that were glazed from the old bucket that also turned
green, so it was not just my batch. Based on the test tiles doing ok,
I dumped my batch into the house's bucket this morning, so I could
have my bucket back for more experimenting :-)
I looked for the P. Pinnell article online, and did not see it, so I will
check the library tomorrow. Did the article have pictures of "snotty green"?
Just the nature of glazing larger pots (the kind that it take two people to
dip
them) is a heavier coating, so...fresh batch full of soda ash, put on too
thick =
snot.
If that was the problem, it is easy enough to fix, thanks!
Pam
.
> There are times when I too get that "green" from Malcolm's shino.
> Malcolm has also had it in the past. Pete Pinnell wrote a series of
> articles in Clay Times a couple of years ago about shino, and he did
> mention that the "snotty green" was caused with a shino glaze
> overloaded with soda ash.
Lee Love on mon 14 jun 04
Ron Roy wrote:
>I have some questions for those that think there are no problems with using
>solubles in glazes.
>
>
Ron. Depending on what you are trying to do, solubles can be
a problem or they can be the answer to the problem. In Hendley's
leatherhard glazing, it is an answer to a problem.
>Why do most of the glazes used by potters not have solubles added?
>
>
From the traditional perspective, because they are already in
the materials and need not be added. If you look most glazes that
have solubles added, typically, we are adding something that was taken
out by industrial processing.
>Why is ash washed?
>
>
To removed some of the solubles and organics. Here in Japan, it
is so it can be controlled so the wet measure is accurate.
Why is ash not washed?
To keep the fluxing ability in the ash and the variety it
provides. This is where those great runny ash glazes come from.
In St. Paul, I never washed my wood ash. Here, I do not wash
the ash for the Irabo, runny ash glaze, because it looses "character" if
you wash it.
>Why do we have frits?
>
>
Industry developed them for controlling the industrial process.
They are useful if you are firing at lower temps. They are a safer
way to use lead in glazes and enamels. Here in Japan, where
stoneware temps are the focus, frits are not very common. If you look
at Leach's book on Hamada, the only place they are mentioned are for
fritting lead and using in enamels.
>Why do some glazes settle out badly?
>
>
The most common reason in my glazes is either because the glaze
is mostly made of stone, as in my chun glaze, or because the glaze is
all calcinated stone, as is the case with Mashiko kaki. One of the
advantages of synthetic kaki is the clay content, which helps suspend
the glaze.
>Why do some glazes thicken over time?
>
>
One reason is because in the glazing, water is taken
out of the glaze faster than the other materials. The solution here,
to get consistency, is to skim off the water before you use it and then
adding water according to the thickness of the pot to be glaze.
Of course, this thickening caused by soda ash is used to
advantage in leatherhard glazing.
>Why do some clays bloom?
>
>
Because they are unprocessed and are living. My greatest
joy here in Japan is using natural clay. If I go back home, I hope to
figure out a way to keep using natural clay. Hamada once said that
they way a potter should decide upon his choices of sites for his
pottery is to choose a site that is next to a deposit of good clay.
>Why do some clays exhibit unusual fit problems when solubles are present in
>glazes.
>
>
Because the maker has not made proper adjustments. As we
know, the Wirt shinos all have lithium in them.
>Why do some potters have problems with crystals forming in the glaze bucket?
>
>
>
Because they choose to use Wirt shinos.
--
in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Paul Herman on tue 15 jun 04
Hi Ron,
My replies, below:
----------
>From: Ron Roy
> I have some questions for those that think there are no problems with using
> solubles in glazes.
>
> Why do most of the glazes used by potters not have solubles added?
That depends on your definition of soluble. They choose to use what they
want. I think all glazes have solubles to some degree. Think of
feldspar, nepheline syenite, frit, clay. Are any of those 100%
insoluble? Is epsom salt?
>
> Why is ash washed?
Well Ron, I can testify, all ash is not washed. For the ash that IS
washed, it is to remove some solubles. I wash the ash for one of my
glazes, for the rest I don't. I relish the ability to decide for myself.
>
> Why do we have frits?
All kinds of reasons, too many to list here. Of course you know that
frits are soluble to some degree?
>
> Why do some glazes settle out badly?
Too much frit? Just kidding, again too many reasons to list, but here's
a couple: large amounts of 'stone' in the glaze, little or no clay, a
preponderance of the wrong KIND of solubles. If my glaze settles too
fast, I add epsom salts (note: more solubles).
>
> Why do some glazes thicken over time?
Evaporation thickens glazes quickly out here in the desert. You should
see the fuzz that developes on some of the shino buckets.
>
> Why do some clays bloom?
Not sure what you mean by this, but if I leave my bag of wet clay in a
well lit place, it will get a little mossy forest growing on it, kind of
like a terrarium. It's really quite lovely in a miniature kind of way.
>
> Why do some clays exhibit unusual fit problems when solubles are present in
> glazes.
Hmmmm, I haven't had this problem, but shino glazes crackle anyway. And
of course, ALL glazes contain solubles to some degree.
>
> Why do some potters have problems with crystals forming in the glaze bucket?
I have had crystals floating in glazes, but as to it being a "problem",
no. I seived them out and tested the glaze, finding no visible
difference (it was a ^10 clear). After floor heat was put in the studio,
the little crystals went away. It may be disturbing to some to see those
little chunks in the bucket, and they may worry because their formula
has changed. Others deal with it in their own way. My requirements for
exactitude are different from other people. Can you accept that, Ron?
Fun glazes,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
Vince Pitelka on wed 16 jun 04
> Paul, something just dawned on me.... All woodfirers love solubles,
> or they'd fire in gas or oil instead. Of course, folks in
> "industry" think we are crazy, because we give up some control and look
> forward to the unexpected graces the kiln provides.
Lee -
Right about the second part - the unexpected graces are the best. But I
don't get the first part . The ash is not a soluble material unless it is
mixed with water, so woodfirers don't necessarily love soluble materials
unless they use ash in a glaze applied to their pots. I know that you use
ash in lots of your glazes, and many woodfirers use ash glazes, but it is
misleading to say that all woodfirers love soluble materials.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Lee Love on wed 16 jun 04
Paul Herman wrote:
Ron Asked:
>>Why is ash washed?
>>
>>
>
>Well Ron, I can testify, all ash is not washed. For the ash that IS
>washed, it is to remove some solubles. I wash the ash for one of my
>glazes, for the rest I don't. I relish the ability to decide for myself.
>
Paul, something just dawned on me.... All woodfirers love solubles,
or they'd fire in gas or oil instead. Of course, folks in
"industry" think we are crazy, because we give up some control and look
forward to the unexpected graces the kiln provides.
Woodfirers often talk about the unique characters of the flame in a
wood kiln. Actually, gas and oil has "flame" too. What makes the
wood flame different are the soluble materials it carries. So
actually, wood firers fire with wood for the soluble materials and
variety that are added by the wood fuel.. Of course, playing with
fire could be an even more important reason. ;-)
So, wood firers by natural are a little bit nutz I guess.
--
in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Ron Roy on wed 16 jun 04
Hi Paul,
Yes - always some solubles - but why use materials that have the oxides
already combined - so they don't go into solution. Can you imagine the
results if you tried to use sodium, potassium and boron in sufficient
quantities to melt a glaze?
Perhaps I should have said - why is some ash washed?
Some frits ar not very soluble in water at all - others are more so but
they in the great minority.
Yes Epsom salts do help suspend glazes - but there can be problems - those
solubles tend to wind up at the rim - carried by the water as it evaporates
- if the pot is dried right side up. The salts then flux that clay more -
during glazing that clay at the rim will absorb less glaze.
If you are going to use solubles you need to know what the results may be
and how to deal with them.
The kind of bloom I am talking about is on fired clay - Tuckers tests their
raw materials so I see this on many of the ball clays, fire clays and even
kaolins. It is due to the salts migrating to the upper surfaces as the clay
dries. You can see how - if there is too much - this will have an effect on
the quality of the pots - different layers in the clay and glazes - all
having different expansion rates.
It can be quite evident on unglazed earthen ware and is called scumming -
bariam carbonate is used in small quantities to render the solubles -
insoluble.
Anyway - thanks for answering - no harm in exploring the advantages and
disadvantages and hopefully others will contribute to our understanding.
RR
>>From: Ron Roy
>> I have some questions for those that think there are no problems with using
>> solubles in glazes.
>>
>> Why do most of the glazes used by potters not have solubles added?
>
>That depends on your definition of soluble. They choose to use what they
>want. I think all glazes have solubles to some degree. Think of
>feldspar, nepheline syenite, frit, clay. Are any of those 100%
>insoluble? Is epsom salt?
>
>>
>> Why is ash washed?
>
>Well Ron, I can testify, all ash is not washed. For the ash that IS
>washed, it is to remove some solubles. I wash the ash for one of my
>glazes, for the rest I don't. I relish the ability to decide for myself.
>
>>
>> Why do we have frits?
>
>All kinds of reasons, too many to list here. Of course you know that
>frits are soluble to some degree?
>
>>
>> Why do some glazes settle out badly?
>
>Too much frit? Just kidding, again too many reasons to list, but here's
>a couple: large amounts of 'stone' in the glaze, little or no clay, a
>preponderance of the wrong KIND of solubles. If my glaze settles too
>fast, I add epsom salts (note: more solubles).
>
>>
>> Why do some glazes thicken over time?
>
>Evaporation thickens glazes quickly out here in the desert. You should
>see the fuzz that developes on some of the shino buckets.
>
>>
>> Why do some clays bloom?
>
>Not sure what you mean by this, but if I leave my bag of wet clay in a
>well lit place, it will get a little mossy forest growing on it, kind of
>like a terrarium. It's really quite lovely in a miniature kind of way.
>
>>
>> Why do some clays exhibit unusual fit problems when solubles are present in
>> glazes.
>
>Hmmmm, I haven't had this problem, but shino glazes crackle anyway. And
>of course, ALL glazes contain solubles to some degree.
>
>>
>> Why do some potters have problems with crystals forming in the glaze bucket?
>
>I have had crystals floating in glazes, but as to it being a "problem",
>no. I seived them out and tested the glaze, finding no visible
>difference (it was a ^10 clear). After floor heat was put in the studio,
>the little crystals went away. It may be disturbing to some to see those
>little chunks in the bucket, and they may worry because their formula
>has changed. Others deal with it in their own way. My requirements for
>exactitude are different from other people. Can you accept that, Ron?
>
>Fun glazes,
>
>Paul Herman
>Great Basin Pottery
>Doyle, California US
>http://www.greatbasinpottery.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.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Paul Herman on wed 16 jun 04
Lee,
Are you kidding me? Sometimes playing with fire is the MAIN reason.
I think of the physical nature of the wood flame as being both solids
and vapors. The alkalies like sodium, potash etc. could be actually
"dissloved" in the gasses from the fire, while other stuff like calcium
is more like dust, a finely divided solid. The carbon compounds are
both, solid and dissolved.
Then there's oxygen and nitrogen and water, oh dear.
And yes of course woodfirers are insane to most people, but from my
point of view there is room and need for our brand of insanity.
What do you think Clayart, is there room for us all?
best,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: Lee Love
> Woodfirers often talk about the unique characters of the flame in a
> wood kiln. Actually, gas and oil has "flame" too. What makes the
> wood flame different are the soluble materials it carries. So
> actually, wood firers fire with wood for the soluble materials and
> variety that are added by the wood fuel.. Of course, playing with
> fire could be an even more important reason. ;-)
>
> So, wood firers by natural are a little bit nutz I guess.
Paul Herman on wed 16 jun 04
Hi Ron,
Thank you for explaining what "bloom" is.
I had this condition in the past, where salts would be deposited on the
rims of plates during drying, and especially the saucers of
butterdishes. After the glaze firing, the rims would be pitted and
rough, arrggh! It was disturbing, and ruined some otherwise satisfactory
ware.
Anyway, I addressed the problem by changing my drying practice. After
throwing, the plates were covered with plastic and slow dried for a day
or so. After trimming, they were turned upside down to finish drying.
This had the effect of spreading the salts out over the whole back of
the plate, eliminating the concentrations on the lip. Butterdishes, I
started drying the top and bottom on separate bats, with the bottoms
turned over. It worked.
That was some years ago, and using my old brown stoneware, which had a
high percentage of fireclay. Happily, my new family of claybodies, which
are grey or white, don't seem to have as much bloom, and I just let them
dry. They were developed because one of the fireclays (Ione)
disappeared, and I wanted to use these bodies in wood and gas firings,
so they are lighter.
Good clay, happy mixing, etc,...
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: Ron Roy
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: mixing shinos question, soda ash film
>Date: Wed, Jun 16, 2004, 11:24 AM
>
>
> The kind of bloom I am talking about is on fired clay - Tuckers tests their
> raw materials so I see this on many of the ball clays, fire clays and even
> kaolins. It is due to the salts migrating to the upper surfaces as the clay
> dries. You can see how - if there is too much - this will have an effect on
> the quality of the pots - different layers in the clay and glazes - all
> having different expansion rates.
>
> It can be quite evident on unglazed earthen ware and is called scumming -
> bariam carbonate is used in small quantities to render the solubles -
> insoluble.
>
> Anyway - thanks for answering - no harm in exploring the advantages and
> disadvantages and hopefully others will contribute to our understanding.
>
> RR
Ivor and Olive Lewis on thu 17 jun 04
Dear Paul Herman,
An interesting description.
When you speak of <actually "dissloved" in the gasses from the fire, >> are you telling
us that the ashes, which contain wood residues in the form of Sodium
carbonate and Potassium carbonate, take on the nature of a solution in
the envelope of the flames?
Or are you giving us a romantic metaphor?
Or have your realised that, at the extremes of temperature in the
later stage of a wood firing, these compounds are transported through
the kiln as fluid droplets. In this state, providing the Ware is
sufficiently hot, then the chemical reaction will take place as molten
alkali metal carbonates impinge on free silica in the clay. This must
be the source of those superb rivulets of glaze which we all admire.
Clayart ? Room for All? Yes! Especially a few more sceptics.
----- Original Message -----
From: "Paul Herman"
To:
Sent: Thursday, 17 June 2004 1:03
Subject: Re: mixing shinos question, soda ash film
> Lee,
>
> Are you kidding me? Sometimes playing with fire is the MAIN reason.
>
> I think of the physical nature of the wood flame as being both
solids
> and vapors. while other stuff like calcium
> is more like dust, a finely divided solid. The carbon compounds are
> both, solid and dissolved.
>
> Then there's oxygen and nitrogen and water, oh dear.
>
> And yes of course woodfirers are insane to most people, but from my
> point of view there is room and need for our brand of insanity.
>
> What do you think Clayart, is there room for us all?
>
> best,
>
> Paul Herman
> Great Basin Pottery
> Doyle, California US
> http://www.greatbasinpottery.com/
>
> ----------
> >From: Lee Love
>
> > Woodfirers often talk about the unique characters of the flame in
a
> > wood kiln. Actually, gas and oil has "flame" too. What
makes the
> > wood flame different are the soluble materials it carries. So
> > actually, wood firers fire with wood for the soluble materials
and
> > variety that are added by the wood fuel.. Of course, playing
with
> > fire could be an even more important reason. ;-)
> >
> > So, wood firers by natural are a little bit nutz I
guess.
>
>
______________________________________________________________________
________
> 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.
Lee Love on thu 17 jun 04
Vince Pitelka wrote:
> The ash is not a soluble material unless it is
>mixed with water,
>
To carry on in your vein ;-) , If you look up the
definition of soluble, it is an adjective: (of a substance) capable of
being dissolved in a solvent. Water is not the only solvent.
On the other hand, water is also introduced into the kiln
environment when burning wood. How the water effects the glazes and
clay body depends on what part of the firing it is introduced. If you
introduce it at high temperature, it immediately is broken down into
oxygen and hydrogen. The hydrogen is a reducer. If introduced
during the cooldown, the water is not broken down chemically and tends
to reoxidizes the clay body. Chinese brick makers used water on the
coals at the end of the firing to turn buff colored bricks red. There
is an excellent article in the Ceramics Technical that my wood kiln
appears in (just cleaned the computer room and cannot find it! Sorry!)
The soluble materials in wood are released in the burning
and travel throughout the kiln in the form of a gas. The action of
these materials in the fluid ash at temperature are very similar to what
we see in liquid. That is why we can add solubles to our gas or
electric fired glazes to capture some of the life/variability, we see in
wood fired work.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Paul Herman on thu 17 jun 04
Greetings Ivor,
Yes, of course you are right, tiny droplets of flux are cruising around
in there too. I wasn't intending it to be a romantic metaphor, but
that's alright, I like romance and metaphor. And yes, the flame envelope
seems to behave like a solution, in my mind anyway.
The kiln is a chemical reaction chamber, and the flames are full of
reactive stuff. The flame is like a brush loaded with glaze. You can't
rigidly control the brush, but after a few firings, patterns start to
become evident, allowing the potters to take advantage of different
effects in different zones.
Now I will get into some heavy speculation, based only on my
observations. The back sides of the pots, facing away from flame, get
nice warm colors and a very thin glaze of sorts. The colors suggest
sodium. Perhaps the tiny droplets are more able to get around to the
back and stick, than the 'heavier' solids like calcium.
Glad to hear there's room for the insane.
good firings,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: Ivor
> Dear Paul Herman,
> An interesting description.
> When you speak of <> actually "dissloved" in the gasses from the fire, >> are you telling
> us that the ashes, which contain wood residues in the form of Sodium
> carbonate and Potassium carbonate, take on the nature of a solution in
> the envelope of the flames?
> Or are you giving us a romantic metaphor?
> Or have your realised that, at the extremes of temperature in the
> later stage of a wood firing, these compounds are transported through
> the kiln as fluid droplets. In this state, providing the Ware is
> sufficiently hot, then the chemical reaction will take place as molten
> alkali metal carbonates impinge on free silica in the clay. This must
> be the source of those superb rivulets of glaze which we all admire.
> Clayart ? Room for All? Yes! Especially a few more sceptics.
Lee Love on thu 17 jun 04
Ron Roy wrote:
>If you are going to use solubles you need to know what the results may be
>and how to deal with them.
>
We agree!
Like John Lennon said, "There are no problems, only
solutions."
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
Ivor and Olive Lewis on fri 18 jun 04
Dear Paul Herman,
In a classical physical sense Flames are Fluids in motion.
Yes, there is an infinity of Chemistry at work in every kiln, but in
wood stoking and Oil firing it reaches its peak performance.
Physically there is an interplay between Gas Velocity and Gravity
which combines the forces of both to govern the distribution of
particulate, non particulate compounds and thermal energy. The
behaviour of the particulate matter will be governed by size and
Density. A low velocity will allow Gravity to exert its influence.
T'would be interesting to consider this using the Fluidic Ideas of
Leonard Da Vinci !!
Always room at the Inn for the insane. Out number those who are sane.
Few have a certificate to prove that fact
Ivor Lewis.
Redhill,
S. Australia.
Ron Roy on fri 18 jun 04
Hi Paul,
Good solution - you could also have added a little barium carb and it would
tie up the salts rendering them non soluble.
I remember - when they still used Gold Art in the bodies at Tuckers - one
of the worst blooming clays.
Tuckers has drawers full of bars from testing the raw clays that come in -
it is interesting to see the bloom change from shipment to shipment -
another reason to have a diveristy of clays in a cly body - to help
minimise the problems caused by solubles in clay.
RR
>Thank you for explaining what "bloom" is.
>
>I had this condition in the past, where salts would be deposited on the
>rims of plates during drying, and especially the saucers of
>butterdishes. After the glaze firing, the rims would be pitted and
>rough, arrggh! It was disturbing, and ruined some otherwise satisfactory
>ware.
>
>Anyway, I addressed the problem by changing my drying practice. After
>throwing, the plates were covered with plastic and slow dried for a day
>or so. After trimming, they were turned upside down to finish drying.
>This had the effect of spreading the salts out over the whole back of
>the plate, eliminating the concentrations on the lip. Butterdishes, I
>started drying the top and bottom on separate bats, with the bottoms
>turned over. It worked.
>
>That was some years ago, and using my old brown stoneware, which had a
>high percentage of fireclay. Happily, my new family of claybodies, which
>are grey or white, don't seem to have as much bloom, and I just let them
>dry. They were developed because one of the fireclays (Ione)
>disappeared, and I wanted to use these bodies in wood and gas firings,
>so they are lighter.
>Paul Herman
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Paul Herman on sat 19 jun 04
Greetings Ivor,
Regarding the motions of fluids and liquids, I have a wonderful book on
the subject. Sensitive Chaos, the creation of flowing forms in water and
air, by Theodor Schwenk. Published by Schocken Books, N7438.S4513 1976.
I think it's still available, a friend was able to find it a few years
ago.
Sometimes (when we're lucky) these flowing patterns show up on our
woodfired pots. I'm working on getting it to be more than just luck.
Gee, I feel like I've come full circle, recommending a book to you,
Ivor!
Good reads,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: Ivor
> Dear Paul Herman,
> In a classical physical sense Flames are Fluids in motion.
> Yes, there is an infinity of Chemistry at work in every kiln, but in
> wood stoking and Oil firing it reaches its peak performance.
> Physically there is an interplay between Gas Velocity and Gravity
> which combines the forces of both to govern the distribution of
> particulate, non particulate compounds and thermal energy. The
> behaviour of the particulate matter will be governed by size and
> Density. A low velocity will allow Gravity to exert its influence.
> T'would be interesting to consider this using the Fluidic Ideas of
> Leonard Da Vinci !!
> Always room at the Inn for the insane. Out number those who are sane.
> Few have a certificate to prove that fact
> Ivor Lewis.
> Redhill,
> S. Australia.
Ann Brink on sat 19 jun 04
Hello Paul, and Ivor
I have a book you might like, "Turbulent Mirror, an illustrated guide to
Chaos Theory and the Science of Wholeness" . It has a lot of illustrations &
graphics. I don't have a scientific education at all, but found this
fascinating. ISBN #0-06-016061-6. The authors are John Briggs and F. David
Peat.
Good firings,
Ann Brink, still enjoying the wood-fired pots!
----- Original Message -----
From: "Paul Herman"
> Greetings Ivor,
>
> Regarding the motions of fluids and liquids, I have a wonderful book on
> the subject. Sensitive Chaos, the creation of flowing forms in water and
> air, by Theodor Schwenk. Published by Schocken Books, N7438.S4513 1976.
> I think it's still available, a friend was able to find it a few years
> ago.
>
Ivor and Olive Lewis on sun 20 jun 04
Dear Paul Herman,
Thank you for your information. I will pass that title on to the
library next week. If it is our system they will get it for me.
What goes around comes around.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Ivor and Olive Lewis on sun 20 jun 04
Dear Ann Brink,
Thank you for that information. Another one for the library to find
for me.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
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