Craig Martell on tue 1 aug 00
Hi:
I've had a lot of off list as well as on list responses to my blue celedon
post so I thought I'd have a go at a quick response and then do some follow
up stuff later and address some of the posts more thoroughly.
Here is the basic recipe that produced a blue celedon for me. I've
included the seger formula so folks abroad can plug in their raw materials
if they want to try this glaze. Here 'tis, without the colorant which is
1% black iron oxide. I used black iron because I've been told that black
iron will produce blue celedons more readily than other types of iron. I
will test red iron and yellow iron in this base and give you all my
results. Also, Kingman is a potash spar that is no longer available. In
the oxide analysis, it contains 12% potassium, as does kona a-3 potash
spar. Custer and g-200 have about 10% potassium.
Blue Celedon cone 10R
=====================
Kingman feldspar.... 55.17 55.17%
whiting............. 14.15 14.15%
silica.............. 30.68 30.68%
========
100.00
CaO 0.60* 8.53%
K2O 0.30* 7.07%
Na2O 0.10* 1.65%
Al2O3 0.43 11.02%
SiO2 4.70 71.67%
Fe2O3 0.00 0.07%
Cost/kg 0.04
Si:Al 11.04
SiB:Al 11.04
Expan 7.45
This glaze is as close as I can come to Tichane's sky blue celedon seger
formula with the raw materials that are available to us here in the US. I
don't want to use frits. It's a well balanced, durable glaze and this
seger is totally food safe etc. The thing I like is that there is enough
alumina in the glaze without an addition of clay. For suspension, I added
2% Hecta Brite, which is a brand of hectorite. You can use macaloid or vee
gum cer to suspend the glaze. If you need to use kaolins in a blue
celedon, use grolleg which is a kaolin very low in titanium. If you have
blue celedons that you are currently using with other kaolins such as EPK
or Tile #6, try subbing grolleg and you'll see an improvement in color. As
John Britt pointed out, the clay body is important for the blues too. If
your clay has a considerable amount, or maybe even just some titanium. Try
a grolleg porcelain slip over your body to improve the blue. My suggestion
for a starting point would be: 50% grolleg, 25% potash feldspar, and 25%
silica for the slip.
That's about it for now. I just got back from helping my wife at a show
and I'm amazed that I was able to write this much. :>) Yawn!!!
later, Craig Martell in Oregon
James Bowen on mon 24 mar 03
I saw some ancient Chinese Song Dynasty pots once that
looked like
porcelain, and were glazed in a transparent
Caribbean blue glaze. The white of the porcelain shows
through and the glaze pools in surface marks beautifully. I
have always thought of this as Blue Celadon. Am I wrong?
"Ours is a world of nuclear giants and ethical infants. We
know more about war than we know about peace, more about
killing than we know about living. We have grasped the
mystery of the atom and rejected the Sermon on the Mount. "
Omar Bradley, World War II General and Chairman of the Joint
Chiefs of Staff under Harry Truman
iandol on tue 25 mar 03
Dear James Bowen,
You are probably correct in your assumption. I read that Sky Blue was a =
treasured colour. Light, Translucent, Vitreous sonorous bodies were =
known during the Song Era.
Blue becomes possible when the level of Titanium Dioxide is low in both =
the rocks from which the clay is formed and in the rocks which =
contribute to the glaze.
Best regards,
Ivor Lewis, Redhill, South Australia
mel jacobson on mon 30 nov 09
for some reason, i get blue celedon, even with
stoneware.
had some at the clayart room last year/pheonix.
blue as can be.
must be the firing.
as, it is 1234, with 2 percent iron ox.
nice blue.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
new book: http://www.21stcenturykilns.com
mel jacobson on wed 13 apr 11
been out of the loop for a bit, but had a kiln full open today.
i had a commission for some big pitchers/some other stuff and she
loves celedon with iron red. (house fire, she lost her entire collection
of my pots. insurance will let her replace them all...so, i am half done.
(she had all the shards...)
so, this big pitcher came out...nice blue celedon.
all the celedon in the kiln had that nice soft blue.
clayart page of my website...only picture.
it is a standard leach 1234/3 percent iron. medium reduction.
it is a mystery. most get green, i get blue.
not kick'n, but that is what i get.
nothing done special.
i have had that rotten ever lasting cold, flue crap for almost a
month. nceca was a struggle as i was so damn tired.
finally feeling better. i thought it was gone, but came back
like a vengeance after nceca.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
new book: http://www.21stcenturykilns.com
alternate: melpots7575@gmail.com
Craig Edwards on fri 15 apr 11
hello Mel; I to use the Leach 4321 recipe with 1.5% black iron oxide. with
medium redux get a nice blue. I start redux about 1550F, with a redux cool
to 1500f and then strike it with heavy redux for 10min. Love that blue.
Hope you are feeling better, spring is coming soon.
Make Good Pots
~Craig
New London MN
http://woodfiredpottery.blogspot.com/
On Wed, Apr 13, 2011 at 7:48 PM, mel jacobson wrote:
> been out of the loop for a bit, but had a kiln full open today.
>
> i had a commission for some big pitchers/some other stuff and she
> loves celedon with iron red. (house fire, she lost her entire collection
> of my pots. insurance will let her replace them all...so, i am half done=
.
> (she had all the shards...)
>
> so, this big pitcher came out...nice blue celedon.
> all the celedon in the kiln had that nice soft blue.
> clayart page of my website...only picture.
>
> it is a standard leach 1234/3 percent iron. medium reduction.
>
> it is a mystery. most get green, i get blue.
> not kick'n, but that is what i get.
>
> nothing done special.
>
> i have had that rotten ever lasting cold, flue crap for almost a
> month. nceca was a struggle as i was so damn tired.
> finally feeling better. i thought it was gone, but came back
> like a vengeance after nceca.
> mel
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
> new book: http://www.21stcenturykilns.com
> alternate: melpots7575@gmail.com
>
--
inge nielsen on fri 15 apr 11
Apropos blue celadon, I would like to share our studio's recipe for blue
celadon on white stoneware, as I think it differs quite a bit from other
blue celadon formulas I have seen. (I'm a relative novice to glazes, but
still...).
Blue celadon
Japanese feldspar 70
whiting 16
*zinc oxide 3
silica 11
gaolin 3
_________
103
RIO 1,5%
Apply fairly thickly. This turns a nice crackle celadon blue on white
stoneware in medium reduction (1260 celcius). Over dark stoneware it is an
attractive speckled green. Japanese feldspar is "*rihua changshi*"in
Chinese, in English I've seen it translated as "Feldspar Clay".
On teadust: I have read with much interest the old threads on teadust in
the clayart archives. I got the original article (by Wu Pengfei) which is
discussed in detail in the clayart archives ("^9 ox. teadust glaze test
results - long"and "mo' betta teadust"), and tested a few of the recipes. I
was a little bit disappointed. In our studio, the above blue celadon recipe
is mixed 1: 2 with the following recipe (mottled brown tianmu) to produce a
lovely satin-like teadust in medium reduction (1260 celcius). We use it
over dark stoneware clay.
Mottled brown tianmu
Potash 70
gaolin 5
magnesium 10
mixed wood ash 20
_________________
110
RIO 8%
sp gr 145
In oxidation (1250 Celcius) on its own it is a nice mottled brown, very
stabile. In reduction, at higher temperatures (1280?) tendency to become
hare-fur like (only sometimes, though!). Mix 2 parts of this prepared
formula with 1 part of prepared blue celadon for teadust.
I have benefited very much myself from the recipes share on clayart and hop=
e
in this way to contribute a little in return.
Inge Nielsen
Taiwan
On Thu, Apr 14, 2011 at 8:48 AM, mel jacobson wrote:
> been out of the loop for a bit, but had a kiln full open today.
>
> i had a commission for some big pitchers/some other stuff and she
> loves celedon with iron red. (house fire, she lost her entire collection
> of my pots. insurance will let her replace them all...so, i am half done=
.
> (she had all the shards...)
>
> so, this big pitcher came out...nice blue celedon.
> all the celedon in the kiln had that nice soft blue.
> clayart page of my website...only picture.
>
> it is a standard leach 1234/3 percent iron. medium reduction.
>
> it is a mystery. most get green, i get blue.
> not kick'n, but that is what i get.
>
> nothing done special.
>
> i have had that rotten ever lasting cold, flue crap for almost a
> month. nceca was a struggle as i was so damn tired.
> finally feeling better. i thought it was gone, but came back
> like a vengeance after nceca.
> mel
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
> new book: http://www.21stcenturykilns.com
> alternate: melpots7575@gmail.com
>
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