Michael Banks on thu 17 dec 98
Ray,
Get the lowest titanium potash feldspar, silica, whiting and kaolin you can
get your hands on and make up a feldspathic glaze. Small amounts of iron is
not a problem as it is neccessary for the blue colour. Some k feldspars
with a few percent natural iron content, fire into fantastic blue celadons
in reduction on their own.
The clay you put in the glaze will be crucial as most have significant
disqualifying Ti contents. Suggestions might include a low Ti bentonite,
low Ti hectorite (lithium montmorillonite) or Premium china clay (a very low
Ti white halloysite from New Zealand).
The reasons for Ti "greening" glazes has been debated here before. I
believe it has something to do with the formation of calcium titanite (the
mineral titanite or sphene), or rutile in the glaze, both of which produce a
golden yellow transmission colour, which together with the ferrous iron blue
transmission colour, produces the colour perceived as green.
Cheers,
Michael Banks
Nelson
New Zealand
mjbanks@clear.net.nz
----------------------------Original message----------------------------
I am currently doing some developmental work in the area of celadon glazes
and am wondering if any body could give me an idea as to what makes a Blue
celadon different to a Green celadon. example recipes or seger formulae
would be nice..
thanks in advance....{gee, there have been some interesting threads lately
:)...}
cheers :) Ray Carlton
Craig Martell on tue 25 mar 03
Hello Celadon Enthusiasts:
I'll tell you as much as I can without crashing clayart. Don't want to do
that.
These glazes show their truest color on porcelain. The blue celadons are
at their very best on porcelain bodies that are very low in titanium. If
you are using a claybody that will muddy the blue, you might try some
porcelain slips.
The glaze needs to be applied thick for good color. There is a small
amount of iron in the glaze for color and it's easy to lose the color if
there isn't enough depth. It's always a good idea to do several test tiles
with several thicknesses of glaze on each one. You are looking for the
effect that YOU want.
Blue Celadon cone 9-10Reduction
g-200 feldspar 62.03
wollastonite 12.73
barium carb 4.48
silica 21.37
black iron ox 1.00
macaloid 3.00
BaO 0.10
CaO 0.45
MgO 0.02
K2O 0.30
Na2O 0.13
Al2O3 0.49
SiO2 4.97
Si/Al ratio 10.10 to 1.0
After wet mixing, screen the glaze about 3 times thru at least a 100
mesh. 120 mesh is better. You want to disperse the iron so you get a nice
sky blue with no iron spots, unless you want iron spots. I ball mill the
glaze for an hour and then screen once thru a 100 mesh. The milling does a
swell job of dispersing the iron. When I do tests I just screen 3 times
and it works ok.
If you want to try custer feldspar instead of g-200 it should work OK. I
calculated the glaze with both spars and they are close enough with regard
to the critical oxide, which is potassium. For blue celadons the potassium
in the seger formula should be at about 0,3. Any less and the glaze is
less blue. If barium makes you nervous, you can leave it out but the glaze
won't be as blue and the color will be slightly harder looking. This is a
pretty durable glaze and the barium is low enough so I wouldn't expect any
serious leaching providing the glaze was fired properly and brought to
maturity.
I fire these pots in a 12 hour cycle. Gas kiln fired with propane. I
start reduction at cone 06 and set the oxyprobe at 0.7. I leave the damper
at the 0.7 setting until cone 5 and then I open it a bit to get 0,5 on the
oxyprobe. I let the kiln climb until cone 8 is at about 2 O'Clock and then
I set the damper to get an oxyprobe reading of 0.65 and I hold this until
cone 10 is down. I usually take 2.5 to 3 hours from cone 8 softening until
cone 10 is down. I cut the gas and hold the kiln at top temp for about an
hour with an oxyprobe reading of 0.6. After the soak I shut the kiln down
and close the damper and all ports. I open it about 36 hrs later and hope
for the best! :>) A further thing about the soak. I actually let the
kiln drop slightly during the hour soak. Usually to about cone 9.
Lemme know if any of you have ?'s or need more info.
regards, Craig Martell Hopewell, Oregon
Matt MacIntire on wed 26 mar 03
Craig,
Thank you for all your insights. It is generous of you to share your
hard won successes with us. I'm sure that many others also appreciate
learning from your experience.
Two questions, if I may...
1. Does the inclusion of macaloid keep the glaze in suspension well?
Or does the glaze still settle out quickly? My previous experience with
glazes with no clay make me wonder if one simply has to be willing to
accept a rock hard pan at the bottom of the bucket. I've never used
suspending agents and have always just relied on the clay component of
the glaze for suspension.
2. Why do you use wollastonite instead of whiting? Do you believe
wollastonite influences the blue color, as some have suggested? Or is
it just more convenient for you?
Thanks in advance for your help
Matt
in Silver Spring, MD
conveniently located near Ground Zero
Gail Dapogny on wed 26 mar 03
Craig has given us a valuable nugget of information to store in our glaze
files; I always pay attention to his statements after noticing through the
years that he has intelligent things to say, plus seeing his gorgeous work
on CM last year.
To supplement what Craig wrote, go back in the old Clay Times issues maybe
3-4 years, and read Pete Pinnell's article on blue and green celadons in
his regular column. It too is a treasure of information. It would be
interesting to compare the two. Pete is also someone to pay attention to.
Gail Dapogny in Ann Arbor
Dave Murphy on wed 26 mar 03
Craig:
Thanks for the recipe, I must have copied it before but do not know from
where. More importantly, thanks for the firing info. One question, can I
use bentonite for the suspender or is it too "dirty". I can get macaloid
but have bent. TIA
Barbara Murphy
Waterloo County Pottery
Waterloo Ontario
Canada
david mcbeth on fri 6 feb 04
I have been struggling to get a good blue celadon glaze for cone 10.
I am working with a grolleg porcelain from Standard Ceramics. The
clay throws beautifully but the celadons are coming out greener than
I want. I am using the following glaze...
Vivika Heino Blue Celadon
Whiting 19.6
Potash Feldspar 27.5
EPK 20
Silica 33
Add:
Red Iron Oxide 1 %
After talking with Otto Heino at Christmas time I am adding 1%
Barium Carbonate.
I am trying to fire in heavy reduction and i get asorta bluish tint
but not the light blue I want. I am open to suggestions and hints.
thanks
Dave
--
David McBeth, MFA
Professor of Art
Assistant Director of Honors Programs
330 B Gooch Hall
The University of Tennessee at Martin
Martin, Tennessee 38238
731-587-7416
Craig Martell on fri 6 feb 04
Hello David:
You are using a good clay for blue celadons. Grolleg is very low in TiO2
and that's good.
For good sky blue celadons you need to choose a potash feldspar that has
the highest percentage of potassium on the market. Currently, that is
g-200. When Moose Creek spar becomes available, that will be the best spar
to use. If you calculate glazes, the K2O in the Seger formula needs to be
at, or very near 0.3. This would put the spar at somewhere near 55%. Keep
the sodium as low as possible. The secondary fluxes should be mainly
calcium and barium. You don't want to add any more than about 4.5% barium
to the mix. Keep the silica high and from what I've made in the way of
blue celadons, the optimum silica/alumina ratio is 12 to 1. Black iron
oxide seems to do a better job with color than red. Some people have had
very nice results with synthetic yellow iron oxide. I have no experience
with this stuff, so far.
regards, Craig Martell Hopewell, Oregon
Bruce Girrell on fri 6 feb 04
David,
I just went through a bunch of celadon tests following the methodology of
Tichane. He obtained best color at 50 parts Kona F4, 30 parts silica, 20
parts whiting and one part iron. In replicating his work I fond my best
results near his at 50-20-20-1. One thing that you don't mention is your
application thickness. The color intensifies with thickness. Are you
applying your glaze thickly enough? Which feldspar are you using? Tichane's
color varied strongly with the feldspar.
Just for jollies why don't you dump that EPK? It's not doing anything to
help your color. The result would be nearly a 30-30-20-1 combo which was one
of the ones that produced opalescence for me.
Since doing those tests I also tried Elaine Coleman's celadon and I have to
admit that it's a nice glaze. It cheats by using a tiny amount of cobalt but
it doesn't smack you in the face with cobalt blue. I hesitate to mention it
because it is ridiculously complex - 13 ingredients! - but it did turn out
nice enough that I was willing to mix up another batch.
Bruce Girrell
steve harrison on sat 7 feb 04
Hi David,
Have you tried the old standard recipe;
Pot spar 50%
Silica 30%
Whiting 20%
plus between half and one % iron oxide
This is usually pretty reliable
Best wishes
Steve Harrison
Hot & Sticky Pty Ltd
5 Railway Pde
Balmoral Village
NSW 2571
Australia
http://ian.currie.to/sh/Steve_Harrisons_books.html
On Saturday, February 7, 2004, at 03:49 AM, david mcbeth wrote:
> I have been struggling to get a good blue celadon glaze for cone 10.
> I am working with a grolleg porcelain from Standard Ceramics. The
> clay throws beautifully but the celadons are coming out greener than
> I want. I am using the following glaze...
>
> Vivika Heino Blue Celadon
> Whiting 19.6
> Potash Feldspar 27.5
> EPK 20
> Silica 33
>
> Add:
> Red Iron Oxide 1 %
>
> After talking with Otto Heino at Christmas time I am adding 1%
> Barium Carbonate.
>
> I am trying to fire in heavy reduction and i get asorta bluish tint
> but not the light blue I want. I am open to suggestions and hints.
>
> thanks
>
> Dave
>
> --
> David McBeth, MFA
> Professor of Art
> Assistant Director of Honors Programs
>
> 330 B Gooch Hall
> The University of Tennessee at Martin
> Martin, Tennessee 38238
>
> 731-587-7416
>
> _______________________________________________________________________
> _______
> 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.
>
David Beumee on sat 7 feb 04
> I have been struggling to get a good blue celadon glaze for cone 10
Hi David,
Here is my best blue celedon recipe for cone 10 reduction. Best on
porcelain. Slightly thicker pots allow for a thicker application, which really
brings out the blue. A 12 count dip is possible, as this glaze doesn't run.
Double dipping not recommended. I do an eight hour bisque to cone 08 to leave
the clay very porous. I fire this glaze successfully by beginning reduction
early, at cone 012. The main thing is steady reduction throughout the firing,
not necessarily heavy reduction.
At cone 9 I reoxidize the atmosphere through cone 10 touching. I have a fiber
kiln with ITC coating, and it cools pretty quickly.
The expansion of this glaze was worked on by glaze guru Paul Lewing. It's my
best glaze, and also reacts beautifully to copper, due to the presence of tin
in the recipe. Best of luck and please tell us how it works for you.
J-91 Blue Celedon, cone 10 reduction, David Beumee/Paul Lewing
33 neph sy
14 whiting
49 A-25 Imsil silica
1 Red Iron Oxide, 99%pure
1 Bone ash
2 Macaloid or Bentone MA
add - 1% tin oxide
Mix the dry ingredients together in a sealed bag to disburse the iron
evenly. Add 1 gram dry mixture to 1ml water and add Epsom Salts solution to
flocculate.
David Beumee
Earth Alchemy Pottery
Lafayette, CO
> I have been struggling to get a good blue celadon glaze for cone 10.
> I am working with a grolleg porcelain from Standard Ceramics. The
> clay throws beautifully but the celadons are coming out greener than
> I want. I am using the following glaze...
>
> Vivika Heino Blue Celadon
> Whiting 19.6
> Potash Feldspar 27.5
> EPK 20
> Silica 33
>
> Add:
> Red Iron Oxide 1 %
>
> After talking with Otto Heino at Christmas time I am adding 1%
> Barium Carbonate.
>
> I am trying to fire in heavy reduction and i get asorta bluish tint
> but not the light blue I want. I am open to suggestions and hints.
>
> thanks
>
> Dave
>
> --
> David McBeth, MFA
> Professor of Art
> Assistant Director of Honors Programs
>
> 330 B Gooch Hall
> The University of Tennessee at Martin
> Martin, Tennessee 38238
>
> 731-587-7416
>
> ______________________________________________________________________________
> 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.
Joyce Lee on sat 7 feb 04
Bruce mentioned using Elaine Coleman's blue
celadon. I, too, even as a newbie, used this
glaze..... no problem getting the sky blue ......
desert sky blue..... beautiful. However, it
didn't have.... for me...... much appeal all by
itself on a pot. It looks better on carved pots
or with a second color (tenmoku is a nice
contrast)
on the rim or bottom..... This blue celadon
didn't craze either.... nor run.
My clay was Tom Coleman's porcelain......
ordered from Aardvark.
Joyce
In the Mojave (sorry if this seems
depressing; tell me so and I'll knock it
off; some have mentioned that an occasional
statement about how I'm "handling" life's
travails helps them.) where I just returned from
my Saturday breakfast Good Grief! group
at the local Casa Java. We laughed for most
of the two
hours .... tears in eyes or not ...... I highly
recommend such a group to start your
weekend. Energizing.
Craig Edwards on sat 7 feb 04
Hi David;
There is a good blue celadon in B Leach's " A Potter's Book". One more
reason to read his book. :O) I put some photos of a cup from the last
firing. On the journal link below. It was wood fired so fly ash
contributed to the way it colored up. Also I think that black iron oxide
instead of red helps somewhat.
http://www.livejournal.com/~smilingpotter/
Craig Edwards
New London MN
Ivor and Olive Lewis on sat 7 feb 04
Dear David McBeth,
They say the secret to achieving blue celadon is to eliminate Titanium
minerals which are often present in residual quantities in many
commercial clays and minerals which we use.
I think the work done by Dr Tichane confirms this. Get the 2nd Ed or
his book on the topic.
Best regards,
Ivor Lewis. Redhill, South Australia
James Bowen on sun 8 feb 04
If the potassium content of the available feldspars and
feldspar like minerals is insufficient to get a better blue
can the amount be increased by the use of soluable sources
of potassium such as pearl ash (potassium carbonate) or
vegetable ashes, or frits made from these materials?
Hank Murrow on sun 8 feb 04
Dear James;
The answer is a qualified yes. I was very interested in both Potassium
and Phosphorus when I was in school, and learned that they were
concentrated in fruit. So we went to an apple farmer's place and
gathered three garbage cans of pulp from his cider press and reduced
them to ash in the gas bisque kiln. We were able to make glazes that
had that pale blue colour, as well as some fine 'shaner-like' reds
using the ash from the fruit pulp. In general, the closer to the fruit
the wood is, the more K and P there will be in the ash......... the
roots have almost none. When you think about it, it makes some sense
that since the K and the P in fertiliser is mainly for the
fruit.......... that you would find it in that part of the plant.
Cheers, Hank in Eugene
On Feb 8, 2004, at 8:27 AM, James Bowen wrote:
> If the potassium content of the available feldspars and
> feldspar like minerals is insufficient to get a better blue
> can the amount be increased by the use of soluable sources
> of potassium such as pearl ash (potassium carbonate) or
> vegetable ashes, or frits made from these materials?
Ron Roy on sun 8 feb 04
This glaze is way short of alumina so I would expect it to be affected by
dish washing - easy to test for. Make two tiles and leave one in the
dishwasher and keep the other for comparison - If it wre a shiny glaze you
would see some dulling eventually.
> J-91 Blue Celedon, cone 10 reduction, David Beumee/Paul Lewing
>
> 33 neph sy
> 14 whiting
> 49 A-25 Imsil silica
> 1 Red Iron Oxide, 99%pure
> 1 Bone ash
> 2 Macaloid or Bentone MA
> add - 1% tin oxide
>
> Mix the dry ingredients together in a sealed bag to disburse the iron
>evenly. Add 1 gram dry mixture to 1ml water and add Epsom Salts solution to
>flocculate.
This glaze has a low enough expansion to not craze on many clay bodies and
enough alumina and silica to probably be stable at cone 10. I would suggest
trying it with Grollege clay instead of EPK to lower the amount of TiO2.
I calculated it with both G200 and Custer and the extra Barium - the Custer
version has a bit lower expansion because of the extra silica.
RR
>> Vivika Heino Blue Celadon
>> Whiting 19.6
>> Potash Feldspar 27.5
>> EPK 20
>> Silica 33
>>
>> Add:
>> Red Iron Oxide 1 %
>>
>> After talking with Otto Heino at Christmas time I am adding 1%
>> Barium Carbonate.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Krista Peterson on mon 9 feb 04
>I have been struggling to get a good blue celadon glaze for cone 10.
>I am working with a grolleg porcelain from Standard Ceramics. The
>clay throws beautifully but the celadons are coming out greener than
>I want. I am using the following glaze...
I don't know if you want to work with the same glaze formula but I used to use an absolutely gorgeous blue celadon from Kurt Wieser he called Angel Spit Celadon. Well, maybe it had a little green going too. Barnard clay was in it. I'd have to dig for the recipe. Let me know.
Krista Peterson
.
Craig Martell on wed 15 mar 06
Veena responded:
>Yes, in one of your recipes that appeared inCM in May 2002, I did
>substitute Strontium for Barium, and recently tried it
>with all Whiting instead of the Barium.
Hello Veena:
Originally, that glaze used Kingman feldspar which is unavailable. Which
feldspar did you use as a replacement? Strontium would probably be fine
but sometimes it will push a glaze more toward green. The percent is quite
low so I wouldn't necessarily fault the strontium.
>The other recipe of yours that I tried as on Clayart and had no barium,
>unless I got it down wrong. It just contained:
>
>F-4 55.17
>Whiting 14.15
>Silica 30.68
>
>with the addition of 1% Black Iron Oxide
> 2% Macaloid
I have no idea where this glaze with F-4 spar came from. It's not one of
mine unless I've totally lost my memory. This one will more than likely
make a green celadon. I've never made or published recipes for blue
celadons with anything but potash spar.
regards, Craig Martell Hopewell, Oregon
Julene on wed 15 mar 06
During the last couple of years, many clayarters have generously given me a
big lift up onto the shoulders of those generous greats who had shoulders
big enough for us who come after asking the questions. My work on iron
glazes has been most enjoyable and productive because of this help.
The biggest help came with the building of the wood kiln based upon Euan
Craig's design and generously posted by Lee Love. My kiln is built mostly
from materials obtained from Smith-Sharpe, who are a great help and
supplier. The main difference in my design was to use appropriate sized
tile bricks for the floor with insulating bricks over these and tile bricks
for the grates. I highly recommend not using metal grates which will need
replacement. For anybody with questions about building this kiln with
American materials, I will help as I can.
My husband has really enjoyed "High-Fire Glazes", a very informative and
well put together book by John Britt. Wonderful.
But when it comes to getting blue celadons, ours came naturally with the
high temperatures of this kiln and the Grolleg porcelain that I was using.
The celadon recipe is the standard one many use ( 10-20-30-40 with 1 percent
red iron oxide). I have even tried recipes formulated to give blue
celadons, but find this one on the Grolleg porcelain gives the best and
purest blue.
The input from some about creating a website through the use of notepad
helped me to put together the following site to show what I am working on:
www.airstreamcomm.net/~julene
I set it up and verified the code, so if the this can be of help to others
building a site, I offer up the code to be used as needed. Thanks to Bill
Amsterlaw's, whose work and site enables clayarters' websites to be shared
and picked up by the search engines without the need to change a long url
such as this one.
Julene, where the pots are thrown, glazed and waiting for the fire to do
its magic in a world transformed to white.
Veena Raghavan on wed 15 mar 06
Hi Craig,
I have tried your blue celadon with the black iron oxide and get a lovely
blue green. But that sky blue still escapes me!
Veena
I
VeenaRaghavan@cs.com
John Britt on wed 15 mar 06
Veena,
Try this in heavy reduction to cone 10 on a grolleg procelain.
PINNELL CELADON Cone 10
Custer Feldspar 24.50
Silica 34.31
Whiting 19.60
Grolleg Kaolin 19.60
Barium Carbonate 1.96
Tin Oxide 1.00
Let me know if you get a nice baby blue.
Hope it helps,
John Britt
www.johnbrittpottery.com
Craig Martell on wed 15 mar 06
Veena was saying:
>I have tried your blue celadon with the black iron oxide and get a lovely
>blue green. But that sky blue still escapes me!
Hello Veena:
Did you substitute any materials, or perhaps deleted the barium?
regards, Craig Martell Hopewell, Oregon
Veena Raghavan on wed 15 mar 06
Hi Craig,
Thanks so much for your reply. Yes, in one of your recipes that appeared in
CM in May 2002, I did substitute Strontium for Barium, and recently tried it
with all Whiting instead of the Barium.
The other recipe of yours that I tried as on Clayart and had no barium,
unless I got it down wrong. It just contained:
F-4 55.17
Whiting 14.15
Silica 30.68
with the addition of 1% Black Iron Oxide
2% Macaloid
All gave me a beautiful blue green, but not that elusive sky blue. Is Barium
a must for the pale blue?
Thanks in advance.
Veena
In a message dated 3/15/2006 7:31:24 PM Eastern Standard Time,
ashglaze@WVI.COM writes:
>
> Did you substitute any materials, or perhaps deleted the barium?
>
VeenaRaghavan@cs.com
Veena Raghavan on thu 16 mar 06
Hi Craig,
Someone gave me a little Kingman Feldspar, so I used that in the glaze test,
no substitute, but I did substiture the barium with Strontium. It was green
rather than blue.
Sorry, I looked up my notes from Clayart on the one with the F4. You are
certainly right (no you are not losing your memory!), it is not yours. You had
given some advice on it about using macaloid. My apologies.
Thank you again for your help.
Veena
In a message dated 3/16/2006 5:20:07 AM Eastern Standard Time,
ashglaze@WVI.COM writes:
Originally, that glaze used Kingman feldspar which is unavailable. Which
>
> feldspar did you use as a replacement? Strontium would probably be fine
> but sometimes it will push a glaze more toward green. The percent is quite
> low so I wouldn't necessarily fault the strontium.
>
> regards, Craig Martell Hopewell, Oregon
>
VeenaRaghavan@cs.com
lee love on thu 16 mar 06
--- In clayart@yahoogroups.com, Veena Raghavan wrote:
> All gave me a beautiful blue green, but not that elusive sky blue.
On a white body, I get Chun sky blue with this:
Paul's Chun cone 10/11 R
Custer 80
Whiting 7
Flint 7
Wood Ash 4
Bone Ash 2
Y. Ochre 1
Bentonite 1
For puple splash: 3% copper slip on raw body.
These types of glazes get their color the same way that the sky
does, from the bubbles in the glaze caused by the bone ash (P2O5
Phosphorus Pentoxide).
WHY IS THE SKY BLUE?
The blue color of the sky is due to Rayleigh scattering. As light
moves through the atmosphere, most of the longer wavelengths pass
straight through. Little of the red, orange and yellow light is
affected by the air.
However, much of the shorter wavelength light is absorbed by the gas
molecules. The absorbed blue light is then radiated in different
directions. It gets scattered all around the sky. Whichever direction
you look, some of this scattered blue light reaches you. Since you see
the blue light from everywhere overhead, the sky looks blue.
--
Lee In Mashiko, Japan
http://mashiko.org
http://seisokuro.blogspot.com/
dianamp@COMCAST.NET on sun 19 sep 10
As I recall, something in the usual KAOLINS causes the greening.
That is why Hennessy celadon should be looked at.
I might NOT remember correctly but I think it was Titanium
that caused the celadon to go green and you have to choose
a kaolin that has little or none.
Diana Pancioli
William & Susan Schran User on sun 19 sep 10
On 9/19/10 9:50 AM, "dianamp@COMCAST.NET" wrote:
> As I recall, something in the usual KAOLINS causes the greening.
> That is why Hennessy celadon should be looked at.
> I might NOT remember correctly but I think it was Titanium
> that caused the celadon to go green and you have to choose
> a kaolin that has little or none.
Hi Diana,
Yes, titanium is one of the elements to avoid when going after a blue
celadon. That means no American kaolins. Need to use grolleg kaolin from
Great Britian.
Blue celadons also need a glaze high in potassium and calcium. At ^10 this
is fine, everything melts well. At ^6 we have a tough time getting the
calcium to melt well.
We need to source other fluxes and then some secondary fluxes to get a good
melt at ^6 and still move towards a blue color from the iron.
John Hesselberth suggested strontium and I've been thinking more about
lithium as additional fluxes.
Got some tests to run soon, and then more after that.
We'll let folks know what's going on as we see any successes.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Hank Murrow on sun 19 sep 10
On Sep 19, 2010, at 6:50 AM, dianamp@comcast.net wrote:
> As I recall, something in the usual KAOLINS causes the greening.
>=3D20
> That is why Hennessy celadon should be looked at.
> I might NOT remember correctly but I think it was Titanium
> that caused the celadon to go green and you have to choose
> a kaolin that has little or none.
Dear Diana;
You are quite correct about titania causing green shifts in celadons. =3D
American kaolins all have enough Titania to cause this shift, so a =3D
substitution of Grolleg(English) or Limoges(French) kaolin will help to =3D
persevere the blu color. Also keep the Titania-bearing kaolins out of =3D
your clay body for the bluest celadons. Beyond that, a bit of Barium in =3D
the glaze may help. apply it thickly(especially at the top of things), =3D
and don't overfire to glossy, as satiny works best to retain =3D
micro-bubbles that yield the blue color.
Cheers, Hank
www.murrow.biz/hank
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