Jan Wax on mon 2 feb 98
Calling all glaze mavens! We have a beautiful blue-green celadon glaze that
develops a fine crackle over B-mix (white stoneware clay). It is fired in
reduction to just under cone 10, and we use it mainly on decorative pieces,
where the crackle adds to surface interest.However, we have also been using
mugs made of this celadon over B-mix at home for the past five years, and
they show no sign whatsoever of staining - no coffee or tea stains, etc. I
think the B-mix is very well vitrified, so I'm wondering if those in the
know consider this kind of a crackle glaze to be safe for dinnerware. Also,
how would one alter this nepheline syenite glaze so that it would not
crackle? Would it be advisable to start with increasing the flint?
We have pictures of pieces with this glaze in the gallery of our webpage.
http://www.pacific.net/~waxbing. The "Moth and Caterpillar" box is a good
example.
thanks.
Jan
Craig Martell on tue 3 feb 98
At 09:49 AM 2/2/98 EST, Jan wrote:
>----------------------------Original message----------------------------
>Calling all glaze mavens! We have a beautiful blue-green celadon glaze that
>develops a fine crackle over B-mix (white stoneware clay). It is fired in
>reduction to just under cone 10, and we use it mainly on decorative pieces,
>where the crackle adds to surface interest.However, we have also been using
>mugs made of this celadon over B-mix at home for the past five years, and
>they show no sign whatsoever of staining - no coffee or tea stains, etc. I
>think the B-mix is very well vitrified, so I'm wondering if those in the
>know consider this kind of a crackle glaze to be safe for dinnerware. Also,
>how would one alter this nepheline syenite glaze so that it would not
>crackle? Would it be advisable to start with increasing the flint?
Hi Jan:
What's a maven anyway??
The thing about crazed glazes harboring bacteria was hashed out on Clayart a
while back. I don't think that any definite decisions were made, or any
solid conclusions reached. I don't think that a crazed celedon would ever
be dangerous in terms of leaching metals because they are usually colored
with only small amounts of iron, which is not toxic. The bacteria thing is
a relatively unstudied question I think. So I guess that maybe it's just a
matter of opinion. However, ware with a crazed glaze is somewhat weaker
than ware with a glaze that fits well. This is probably so due to the tiny
fractures in the glaze extending into the clay/glaze interface thereby
weakening the body somewhat.
When a glaze has a very fine crackle network, it is a LONG way off in terms
of fit. Nepheline Syenite is a sodium bearing material and soda has a very
high rate of expansion. Neph Sy is also quite low in silica. Both of these
factors contribute to crazing. If you want a celedon that fits, you should
probably dump the Neph Sy and replace it with a potash feldspar. In
essence, you should just use another celedon because you would have to
radically change the molecular formula of this type of glaze to make it fit.
I can make further suggestions about this if anyone is interested. I can
also post a glaze that I formulated that makes a nice clear celedon and fits
most balanced claybodies. You could also do a quadraxial blend with Custer
Feldspar, Whiting, EPK, and Silica that would yield some nice bases that
would be celedon with additions of iron.
regards, Craig Martell-Oregon
Jan Wax on wed 4 feb 98
Craig wrote:
>What's a maven anyway??
Jan: "Maven" = "expert" or "connoisseur". (I think it's a Yiddish word.I
considered "glaze gurus", but that seemed really lame). What's ?
>I can also post a glaze that I formulated that makes a nice clear celedon and
>fits
>most balanced claybodies.
>regards, Craig Martell-Oregon
I'd appreciate that. Is it blue-green?
And many thanks, Craig, for your response to my crazing problem. All those
years I was studying Chaucer when I could have been learning quadraxial
blends! You and several others were helpful. What a great group. I may
continue to use my celadon on the outside of decorative pieces because I
like the way it looks, but I'm going to find other solutions for celadon
dinnerware. Since I like the glaze a lot, perhaps a different clay body
could be a solution.
Jan
Wendy Moore on thu 5 feb 98
Craif,
I would be interested in the clear celadon recipe you mentioned. I am working
on finding a celadon that doesn't craze on the porcelain body that I use. This
is a store mix claybody that I don't have access to the recipe for. I makes it
hard to alter the claybody itself. I am testing all sorts of recipes and doing
blends, etc... TIA for "mavens" like you who make sharing an art form.
Wendy, The Apron Lady
In Muddy, Muggy, mid-Winter, Michigan???
Craig Martell wrote:
> ----------------------------Original message----------------------------
> At 09:49 AM 2/2/98 EST, Jan wrote:
> >----------------------------Original message----------------------------
> >Calling all glaze mavens! We have a beautiful blue-green celadon glaze that
> >develops a fine crackle over B-mix (white stoneware clay). It is fired in
> >reduction to just under cone 10, and we use it mainly on decorative pieces,
> >where the crackle adds to surface interest.However, we have also been using
> >mugs made of this celadon over B-mix at home for the past five years, and
> >they show no sign whatsoever of staining - no coffee or tea stains, etc. I
> >think the B-mix is very well vitrified, so I'm wondering if those in the
> >know consider this kind of a crackle glaze to be safe for dinnerware. Also,
> >how would one alter this nepheline syenite glaze so that it would not
> >crackle? Would it be advisable to start with increasing the flint?
>
> Hi Jan:
>
> What's a maven anyway??
>
> The thing about crazed glazes harboring bacteria was hashed out on Clayart a
> while back. I don't think that any definite decisions were made, or any
> solid conclusions reached. I don't think that a crazed celedon would ever
> be dangerous in terms of leaching metals because they are usually colored
> with only small amounts of iron, which is not toxic. The bacteria thing is
> a relatively unstudied question I think. So I guess that maybe it's just a
> matter of opinion. However, ware with a crazed glaze is somewhat weaker
> than ware with a glaze that fits well. This is probably so due to the tiny
> fractures in the glaze extending into the clay/glaze interface thereby
> weakening the body somewhat.
>
> When a glaze has a very fine crackle network, it is a LONG way off in terms
> of fit. Nepheline Syenite is a sodium bearing material and soda has a very
> high rate of expansion. Neph Sy is also quite low in silica. Both of these
> factors contribute to crazing. If you want a celedon that fits, you should
> probably dump the Neph Sy and replace it with a potash feldspar. In
> essence, you should just use another celedon because you would have to
> radically change the molecular formula of this type of glaze to make it fit.
>
> I can make further suggestions about this if anyone is interested. I can
> also post a glaze that I formulated that makes a nice clear celedon and fits
> most balanced claybodies. You could also do a quadraxial blend with Custer
> Feldspar, Whiting, EPK, and Silica that would yield some nice bases that
> would be celedon with additions of iron.
>
> regards, Craig Martell-Oregon
Craig Martell on thu 5 feb 98
At 09:13 AM 2/4/98 EST, Jan wrote:
>----------------------------Original message----------------------------
>Jan: "Maven" = "expert" or "connoisseur". (I think it's a Yiddish word.I
>considered "glaze gurus", but that seemed really lame). What's ?
Hi Jan:
is a typists grin symbol. It just means I was asking about Maven in a
good natured way.
My celedon formula is posted at the end of this message. It's a lime green
celedon the way I color it. I use 5% of a native Oregon clay that is very
high in Iron. You could maybe get the same color with 5% or so of Alberta
slip, or Albany. 1 to 2% additions of red or black iron will give celedons.
It is often said that black iron oxide gives bluer celedons, so you might
want to try that. It is important to keep a glazes content of titanium at a
near zero level to develop blue celedons as well. Titanium will encourage green.
I ran your Neph Sy celedon through Insight and you could reduce the crazing
and maybe eliminate it by the direct substitution of potash feldspar for the
Neph Sy. You might want to try both Custer and G-200. Custer is higher in
silica and would be the most effective one to lower the glazes expansion.
G-200 will give a bit better melt I think..........Craig
Martell Clear Celedon Cone 10 Red.........OK for a clear cone 10 Ox glaze
G200 FELDSPAR 30.20 CaO 0.72*
DOLOMITE 4.70 MgO 0.10*
WHITING 15.90 K2O 0.12*
EPK KAOLIN 18.90 Na2O 0.06*
SILICA 30.30 Fe2O3 0.00
======== TiO2 0.00
100.00 Al2O3 0.48
SiO2 3.69
Cost/kg 0.24
Si:Al 7.71
SiB:Al 7.71
Expan 6.72
Jan Wax on fri 6 feb 98
>----------------------------Original message----------------------------
Craig wrote:
>My celedon formula is posted at the end of this message.
Thanks Craig!
>
>I ran your Neph Sy celedon through Insight ...
And thanks again!
And for those of you who haven't been to the digitalfire website, the
address is: http://www.digitalfire.com/magic/toc.htm. This is where
Insight can be found. I learned a lot from reading the glaze information
at this site. Probably most of the seasoned Clayarters already know about
this, but it was new to me.
Jan
crazed but still functional in soggy California
SECOR on sat 21 mar 98
Does any one know the origin of the word "celadon" ? Is there an authoritative r
Thanks - DAN
Dan Wilson on sun 22 mar 98
Dan,
"Celadon: meaning "sea-green," was originaly the name of the shepherd in a
seventeenth century French novel, In the plays of that period the shepherds
usually wore sea-green costumes and the name was applied to the color and
then to the Chinese ceramics of this color which were then coming to the
notice of Europeans."
A footnote from"Art Through the Ages an Introduction to its History and
Significance" by Hellen Gardner. Harcourt, Brace and Company, New York. 1936
dan Wilson
>----------------------------Original message----------------------------
>Does any one know the origin of the word "celadon" ? Is there an
>authoritative r
>
>Thanks - DAN
DIANA PANCIOLI, ASSOC. PROF. on sun 22 mar 98
The word is a French label. Probably used for early Chinese export ware.
My guess would be about 300 years ago. Same root as celery? An
unabridged dictionary would help.
Diana
EMU
On Sat, 21 Mar 1998, SECOR wrote:
> ----------------------------Original message----------------------------
> Does any one know the origin of the word "celadon" ? Is there an authoritative
>
> Thanks - DAN
>
Jon Pettyjohn on sun 22 mar 98
Hi Dan,
Celadon is really a first name, and it's taken from the name of
a character in a popular Italian play from the Middle Ages, it's
said that the character in the play wore a robe of a distinct
greenish (celadon like) color. I wonder if anyone has read it,
or knows where it might be found? My guess would be that the color
of the robe played some part in the story. Spanish and Italian
first names are almost always taken from Saints but I've never
heard of a Saint Celadon.
I don't know the Italian version of the name but in Spanish it's
spelled Celadonia for women and Celadonio for men, I have have
heard of a few people here in the Philippines with that name,
I have a feeling it's less common in Europe today.
Pretty name really, kind of wish I'd named one of my daughters
"Celadonia".
Jon Pettyjohn
Manila
jon@mozcom.com
> ----------------------------Original message----------------------------
> Does any one know the origin of the word "celadon" ? Is there an authoritative
>
> Thanks - DAN
>
EDWIN GOULD on wed 13 may 98
I would like to shift this glaze from a gorgeous blue with a fine surface that p
me to green.
cone 10 reduction
Custer feldspar 50
whiting 6
EPK 4
Barium Carbonate 16
Flint 24
I have been told to simply reduce the barium carbonate; but then what do I incr
I have also been told to simply replace the barium carbonate (gradually with tes
Magnesium carbonate. The glaze formula was given to me with the name choy blue
ANY SUGGESTIONS?
(I am familiar with the toxic effects and risks and precautions of using Bariu
carbonate)
Jim Bozeman on thu 14 may 98
Hello Edwin, Celadon glazes are the only ones I use. If it were me, I
would get rid of the barium carb. You could up the EPK to 10 %. Also,
you could subtract some of the silica and try adding some G-200 spar. On
top of this, you could add some wollastonite. And lastly, to help get
the greenish hue you desire, add 1 to 2 percent red iron ox. Hope this
helps. Test, test, test! Jim in NC
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
Ron Roy on sun 17 may 98
Hi Edwin,
This sounds like the perfect application to use Strontium Carb instead of
Barium.
Are you using iron to get the colour?
Just leave out the Barium and replace it with 12 (3/4 of 16) Strontium
carb. This will also will lower the expansion. The original expansion is on
the high side and is probably crazing on some bodies.
Another version would be - leave out the Barium and raise the whiting to 14
- same flux to silica/alunmina - lower expansion - cheaper than the
Strontium and Barium version. I suggest testing both and a combination of
the two. All three (without the Barium) revisions look like they will be
durable and food safe at cone 10.
The Barium version is oversupplied with BaO and should not be used on food
bearing surfaces.
>----------------------------Original message----------------------------
>I would like to shift this glaze from a gorgeous blue with a fine surface
>that p
>me to green.
> cone 10 reduction
>
> Custer feldspar 50
> whiting 6
> EPK 4
> Barium Carbonate 16
> Flint 24
>
>I have been told to simply reduce the barium carbonate; but then what do
>I incr
>I have also been told to simply replace the barium carbonate (gradually
>with tes
>Magnesium carbonate. The glaze formula was given to me with the name choy blue
> ANY SUGGESTIONS?
> (I am familiar with the toxic effects and risks and precautions
>of using Bariu
>carbonate)
Ron Roy
93 Pegasus trail
Scarborough Otario
Canada M1G 3N8
Phone: 416-439-2621
Fax: 416-438-7849
Web page: Home page http://digitalfire.com/education/people/ronroy.htm
Lisa Sheirer on thu 18 jun 98
Speaking of Celadons, could someone tell me if it is better to brush on these
glazes, dip them or pour them?
thanks...
Lisa Sheirer
L_Sheirer@fre.fsu.umd.edu
Craig Martell on fri 19 jun 98
>----------------------------Original message----------------------------
>Speaking of Celadons, could someone tell me if it is better to brush on these
>glazes, dip them or pour them?
Hi:
Celadons need a medium to thick application to develop depth and color.
I've found that pouring and or dipping gives this result much more easily
and efficiently than brushing or spraying. Brushing is probably the least
effective technique to use.
When trying new formulas, I apply the glazes at several thicknesses on test
tiles to determine the possibilities before glazing pots.
regards, Craig Martell-Oregon
sandra m benscoter on fri 19 jun 98
Hi Lisa!
I find dipping very quickly and avoiding runs brings the best results.
Sande
_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]
John Britt on fri 19 jun 98
Dip with no drips.
--
Thanks,
John Britt claydude@unicomp.net
Dys-Functional Pottery
Dallas, Texas
http://www.dysfunctionalpottery.com/claydude
Lisa Sheirer on sun 21 jun 98
Speaking of Celadons, could someone tell me if it is better to brush on these
glazes, dip them or pour them?
thanks...
Lisa Sheirer
L_Sheirer@fre.fsu.umd.edu
Patti Kratzke on tue 2 oct 01
Well, I'm here to learn. I did not know that celadon referred to the
chemistry, rather than the color. But I did note that it is an Oribe,
but when people see it they call it celadone, so I hope no one is misled.
And the pottery.org page that I referred to has extensive information on
celadon glazes (real celadon glazes), that I hope Mike finds useful.
But the oribe is a cool glaze, and might be the effect someone is looking
for.
Thanks for the schoolin'!
On Tue, 2 Oct 2001 09:21:28 -0400 "Lana Reeves" writes:
Hi Patti,
There are at least two answers to your post.
1.) Your glaze is not a celadon. Celadon is a glaze that gets it's
color-- green or blue-- from small amounts of some form of iron fired in
reduction. One of the projects I give to my glaze class is to mix a
glaze base, and add increasing amounts of red iron oxide. Much to their
surprise, 1% iron gives a celadon, increasing amounts can give either
darker, muddy greens, or yellowish brown,but at 9% iron, one ends up with
a temmoku. Your copper glaze is, indeed, an oribe.
2.) If your glaze looks like a celadon, you can call it that, or anything
you want. Whatever works for you.
I'm sure you will get lots of passionate comments on both sides of the
issue.
Lana in Somerville, MA =^..^=
Patti Kratzke
Kingston, WA
pkpotts@juno.com
John Hesselberth on wed 3 oct 01
on 10/2/01 11:01 PM, Patti Kratzke at pkpotts@JUNO.COM wrote:
> But the oribe is a cool glaze, and might be the effect someone is looking
> for.
Hi Patti,
It's also a glaze that has too much copper in it to be stable. Tom Wirt and
Betsy Price had it tested a couple years ago and their results are posted on
my web site. ANY glaze containing more than 5% copper carbonate is likely
to be unstable and only the best will hold 5%. Oribe has what I consider to
be acceptable levels of silica and alumina, but not the preferred levels.
It would probably hold 3% copper without a problem, but, of course would be
a different glaze.
Regards,
John
Web site: http://www.frogpondpottery.com Email: john@frogpondpottery.com
"The life so short, the craft so long to learn." Chaucer's translation of
Hippocrates, 5th cent. B.C.
Wade Blocker on wed 3 oct 01
Patti,
Celadon is the general name given to a color range of subtle green to
blue gray stoneware and porcelain glazes. In the nineteenth century it was
called celadon after a character in a French seventeenth century play who
wore a greyish green costume. However, the more apropriate term is
"greenwares".
Chinese ceramicists have come to accept as greenwares all ceramic wares
having a high fired glaze which is felspathic and contains a small
percentage of iron from 1% to 5%, which gives the glaze a color range from
light bluish green to sea green, olive green,greenish yellow to dark brown
depending on the firing condition of the kiln.
A very interesting book, profusely illustrated, published by the
Southeast Asian Ceramic Society,deals with this subject. Mia in autumnal
ABQ
Earl Brunner on thu 4 oct 01
When I first read this explanation, I thought two things.
1. I've never heard it called that, and
2. We already have the term greenware that means something else
entirely to potters and how confusing that would be.
Mia wrote:
>> Celadon is the general name given to a color range of subtle green to
>> blue gray stoneware and porcelain glazes. In the nineteenth century it was
>> called celadon after a character in a French seventeenth century play who
>> wore a greyish green costume. However, the more apropriate term is
>> "greenwares".
>
>
> Mia -
> Appropriate? For whom? Art historians develop all sorts of terms within
> their own fields of expertise, but altogether those terms have no relevance
> to discussions in the real world. "Greenwares" is such a term. In studio
> ceramics, the appropriate term is "celadon."
> Best wishes -
> - Vince
>
--
Earl Brunner
http://coyote.accessnv.com/bruec/
bruec@anv.net
vince pitelka on thu 4 oct 01
> Celadon is the general name given to a color range of subtle green to
> blue gray stoneware and porcelain glazes. In the nineteenth century it was
> called celadon after a character in a French seventeenth century play who
> wore a greyish green costume. However, the more apropriate term is
> "greenwares".
Mia -
Appropriate? For whom? Art historians develop all sorts of terms within
their own fields of expertise, but altogether those terms have no relevance
to discussions in the real world. "Greenwares" is such a term. In studio
ceramics, the appropriate term is "celadon."
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
lili krakowski on tue 22 jun 04
Brown celadon sounds a bit weird, but never mind.
Celadon is the name of a character in a pastoral novel by one Honore
d'Urfe. The Larouse says 1610-1627; no idea what that means; prob. it
was published serially. L'Astree is the name of the book, and of a
shepherdess. the langorous, shy Celadon loves. The action or inaction
takes place in the 7th Cent. AND the Larouse also tells Astree was the
daughter of Jupiter and Themis. And Celadon has long meant pale green.
Having related all this pedantic stuff: since it is so old and so
nit-picky can we stick to CelAdon, and not update it by substitution of
an E?
Lili
lili krakowski
Constableville, NY 13325
Be of good courage
| |
|
