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alkalinity and ^10 tourquoise gloss

updated wed 27 feb 02

 

Malone & Dean McRaine on fri 1 feb 02


Aloha all. I've been experimenting with ^10 tourquoise glazes for a while
but I'm not that pleased with anything I've done so far. I opened up the
new CM and there on p. 82 is the tourquoise of my dreams being produced in
Jaipur, India. I know I need a high-alkaline base glaze with copper to
produce this color range. Most of the glazes I've seen like this are barium
matts but I want a glossy surface and a non-toxic food safe glaze. I've
also read that high soda glazes, while alkaline, are also prone to crazing
and I want to avoid this fault if possible. The tests I've done haven't
produced the strong tourquoise that I am looking for, possibly they are not
alkaline enough? Anyone have any recipes or suggestions to help me in my
quest?
Thanks and Blessings from Kauai
Dean

Michele Williams on sun 24 feb 02


When somebody comes up with this recipe, I'd like to have it, too. I have a
friend who is Indian who gave me a little piece of turquoise jewelry--strong
blue turquoise--and I'd like to "turquoise her back" so to speak.

Michele Williams

----- Original Message -----
From: "Malone & Dean McRaine"
To:
Sent: Friday, February 01, 2002 3:47 PM
Subject: Alkalinity and ^10 Tourquoise Gloss


> Aloha all. I've been experimenting with ^10 tourquoise glazes for a while
> but I'm not that pleased with anything I've done so far. I opened up the
> new CM and there on p. 82 is the tourquoise of my dreams being produced in
> Jaipur, India. I know I need a high-alkaline base glaze with copper to
> produce this color range. Most of the glazes I've seen like this are
barium
> matts but I want a glossy surface and a non-toxic food safe glaze. I've
> also read that high soda glazes, while alkaline, are also prone to crazing
> and I want to avoid this fault if possible. The tests I've done haven't
> produced the strong tourquoise that I am looking for, possibly they are
not
> alkaline enough? Anyone have any recipes or suggestions to help me in my
> quest?
> Thanks and Blessings from Kauai
> Dean
>
>
____________________________________________________________________________
__
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Michele Williams on mon 25 feb 02


If someone has a recipe like this, I'd like a copy of it, too. An Indian
friend of mine game me a dark blue turquoise, and I'd like to give her one
of my ceramics with that coloring.

Thanks for the blessings from Kauai--shared them with my friend who used to
live there. Can almost feel the breezes now.

Michele Williams




. I opened up the
> new CM and there on p. 82 is the tourquoise of my dreams being produced in
> Jaipur, India. I know I need a high-alkaline base glaze with copper to
> produce this color range. Most of the glazes I've seen like this are
barium
> matts but I want a glossy surface and a non-toxic food safe glaze. I've
> also read that high soda glazes, while alkaline, are also prone to crazing
> and I want to avoid this fault if possible. The tests I've done haven't
> produced the strong tourquoise that I am looking for, possibly they are
not
> alkaline enough? Anyone have any recipes or suggestions to help me in my
> quest?
> Thanks and Blessings from Kauai
> Dean
>
>
____________________________________________________________________________
__
> 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.

Christena Schafale on tue 26 feb 02


At risk of being wrong -- What I have understood from reading and a few
tests is that copper turquoise and crazing are inseparable partners. If
you decrease the high-expansion fluxes enough to get rid of crazing, then
you lose the turquoise color and get a green instead. If I remember the
test results right, adding more silica preserved the blue color and
prevented the crazing but then the glaze didn't melt adequately and went
very dry matt. I don't think you are going to be able to make this a
turquoise, glossy, food-safe, and non-crazed glaze -- you may have to
settle for one or two out of four. I wonder if you could get anything like
the color you want with stains?

Chris


>

Dean from Kauai wrote about turquoise glazes:
> I know I need a high-alkaline base glaze with copper to
> > produce this color range. Most of the glazes I've seen like this are
>barium
> > matts but I want a glossy surface and a non-toxic food safe glaze. I've
> > also read that high soda glazes, while alkaline, are also prone to crazing
> > and I want to avoid this fault if possible. The tests I've done haven't
> > produced the strong tourquoise that I am looking for, possibly they are
>not
> > alkaline enough?



Light One Candle Pottery
209 N Woodrow St
Fuquay-Varina, NC 27526
(919) 567-1098
candle@intrex.net
www.lightonecandle.com

John Hesselberth on tue 26 feb 02


on 2/26/02 7:57 AM, Christena Schafale at christenas@RFSNC.ORG wrote:

> At risk of being wrong -- What I have understood from reading and a few
> tests is that copper turquoise and crazing are inseparable partners. If
> you decrease the high-expansion fluxes enough to get rid of crazing, then
> you lose the turquoise color and get a green instead.

Hi Chris,

At cone 10 I think you may be right, but at lower cones it may be possible.
There you can use boron to offset the high expansion of Na and K. One of
the glazes that will be published in Clay Times in the issue about to be
released is a cone 04 turquoise and, at least on a calculated basis, it does
not have high expansion.

I think I will try to develop one and see if I can get there at cone 6.

John

web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
EMail: john@frogpondpottery.com

"Pots, like other forms of art, are human expressions: pleasure, pain or
indifference before them depends upon their natures, and their natures are
inevitably projections of the minds of their creators." Bernard Leach, A
Potter's Book.

Ruth Ballou on tue 26 feb 02


There's a very interesting article in Ceramics Monthly, Summer 1996 about a
non crazing turquoise at ^04. It was acheived through some innovative body
modifications based on information from the 8th century. It's not clear if
a higher temp clay could likewise be modified. The article is by Nathan
Rafla and it's called "In Search of Samarra Soda".

Ruth Ballou
Silver Spring, Md.

Jennifer F Boyer on tue 26 feb 02


Here's a turquoise Cone 10 glaze I used years ago.

Black Mountain Turquoise

F-4(Soda) Feldspar 40
Whiting 10
EPK 10
Talc 20
Flint 20

Cobalt Carb .5
Chrome 1.0

It's bright and reliable. Not glassy thought, but maybe you
could alter it to suit. It doesn't craze. I haven't looked into
whether it's balanced properly for food safety. Ron might have
an opinion....

Jennifer

Malone & Dean McRaine wrote:
>
> Aloha all. I've been experimenting with ^10 tourquoise glazes for a while
> but I'm not that pleased with anything I've done so far. I opened up the
> new CM and there on p. 82 is the tourquoise of my dreams being produced in
> Jaipur, India. I know I need a high-alkaline base glaze with copper to
> produce this color range. Most of the glazes I've seen like this are barium
> matts but I want a glossy surface and a non-toxic food safe glaze. I've
> also read that high soda glazes, while alkaline, are also prone to crazing
> and I want to avoid this fault if possible. The tests I've done haven't
> produced the strong tourquoise that I am looking for, possibly they are not
> alkaline enough? Anyone have any recipes or suggestions to help me in my
> quest?
> Thanks and Blessings from Kauai
> Dean
>
> ______________________________________________________________________________
> 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.

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802-223-8926
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Imzadi D. on tue 26 feb 02


Hmmm... I know of a beautiful transparent Turquoise semi-gloss/matte cone 10
glaze made up from Laguna Clay's MG-2 base. The potter who used it told me
the colorants she used were a combo of Cobalt Carb and Chrome, but I was too
bemused at the time to fully pay attention to the proportions she stated to
use. I'm gonna have to try the ratio Jennifer stated below to see if I can
get some good results.


In a message dated 2/26/02 3:45:13 PM Pacific Standard Time,
jboyer@ADELPHIA.NET writes:

<< Here's a turquoise Cone 10 glaze I used years ago.

Black Mountain Turquoise

F-4(Soda) Feldspar 40
Whiting 10
EPK 10
Talc 20
Flint 20

Cobalt Carb .5
Chrome 1.0

It's bright and reliable. Not glassy thought, but maybe you
could alter it to suit. It doesn't craze. I haven't looked into
whether it's balanced properly for food safety. Ron might have
an opinion....
>>

Ron Roy on tue 26 feb 02


Alkaline glazes are not hard to make - stopping the crazing and running is
whats hard to do. The higher you fire the better cause you can get more
silica in and silica is a good anti craze.

Hamer has something to say about it - under "blue" and under "Copper oxide."

RR




>When somebody comes up with this recipe, I'd like to have it, too. I have a
>friend who is Indian who gave me a little piece of turquoise jewelry--strong
>blue turquoise--and I'd like to "turquoise her back" so to speak.
>
>Michele Williams

Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513