Craig Martell on thu 1 dec 05
At 06:30 PM 12/1/2005 -0800, you wrote:
>it seems like you know a lot about glazes and no one has replied to my
>posting.
>do you know any clear glaze that has sorta bluish tint to it? LIke the ones
>they used in korean and chinese celadon?
What cone? Will the glaze be fired in oxidation or reduction?
regards, Craig Martell Hopewell, Oregon
Lili Krakowski on thu 1 dec 05
Last week or so, a distressed someone wanted to know why, where the =
glaze was a bit thicker on the pot, it turned bluish. The answer, =
kindly supplied by a gurish person, was that transparent glazes high in =
boron--such as "colemanite" or calcium borate glazes--will turn that =
skim milk "blue" where thick/er.
Just now someone actually WANTS such a glaze .
Here are a few glazes from THE POTTER'S BOOK OF GLAZE RECIPES by =
Emmanuel Cooper.
#67 Speckled transparent glaze c.5
Neph Sy 15
Calcium Borate frit* 50
(Colemanite)
China Clay 17
Flint 18
Rutile 5%
A bright transparent glaze with iron speckles. It will give a blue chun =
effect over a dark clay body.
#68 Chun glaze c5
Feldspar** 45
Whiting 5
Calcium borate frit* 20
(Colemanite) =20
Flint 30
A chun effect glaze caused by trapped air bubbles in the glaze giving a =
soft pale blue colour. It will especially give a blue over a dark clay =
body.
Under the heading of "Stoneware Glazes: Orton cones 5, 6,7 and 8. Sir =
Emmanuel (and nobody's getting a knighthood or whatever makes me happier =
than Cooper's getting one--) lists these:
#141 Chun clear glaze
Feldspar** 50
Zinc Oxide 4
Dolomite 10
Whiting 10
Bentonite 3
Flint 23
In oxidation a clear glaze with a chun translucent blue, especially at =
lower temperatures. In reduction a semi-clear, blue-grey glaze.
#148 wide-firing clear base glaze
Feldspar (soda)** 38
Whiting 14
Zinc Oxide 12
Ball Clay 6
Flint 30
A semi clear 'chun' glaze. In oxidation a semi-translucent, delicate =
'chun' glaze more clear in reduction. =20
*There are many calcium borate frits. The Careful Potter keeps the most =
popular one in her glaze pantry, and tries all when testing a new, but =
unspecific glaze.
** The convention is that where it simply says "FELDSPAR" in a recipe, =
potash spar is meant. Note here that when a soda spar is meant it SAYS =
SO.
All these glazes should be tested, obviously some in blends, and I =
expect the desired effect will be achieved.
Thickness of application matters in achieving the desired effect in this =
case, so thickness should be tested as well.
Tae Kim on thu 1 dec 05
it seems like you know a lot about glazes and no one has replied to my
posting.
do you know any clear glaze that has sorta bluish tint to it? LIke the ones
they used in korean and chinese celadon?
thanks
On 12/1/05, Lili Krakowski wrote:
>
> Last week or so, a distressed someone wanted to know why, where the glaz=
e
> was a bit thicker on the pot, it turned bluish. The answer, kindly
> supplied by a gurish person, was that transparent glazes high in boron--s=
uch
> as "colemanite" or calcium borate glazes--will turn that skim milk
> "blue" where thick/er.
>
> Just now someone actually WANTS such a glaze .
>
>
>
> Here are a few glazes from THE POTTER'S BOOK OF GLAZE RECIPES by Emmanuel
> Cooper.
>
> #67 Speckled transparent glaze c.5
>
> Neph Sy 15
> Calcium Borate frit* 50
> (Colemanite)
> China Clay 17
> Flint 18
> Rutile 5%
>
> A bright transparent glaze with iron speckles. It will give a blue chun
> effect over a dark clay body.
>
> #68 Chun glaze c5
>
> Feldspar** 45
> Whiting 5
> Calcium borate frit* 20
> (Colemanite)
> Flint 30
>
> A chun effect glaze caused by trapped air bubbles in the glaze giving a
> soft pale blue colour. It will especially give a blue over a dark clay
> body.
>
>
> Under the heading of "Stoneware Glazes: Orton cones 5, 6,7 and 8. Sir
> Emmanuel (and nobody's getting a knighthood or whatever makes me happier
> than Cooper's getting one--) lists these:
>
> #141 Chun clear glaze
>
> Feldspar** 50
> Zinc Oxide 4
> Dolomite 10
> Whiting 10
> Bentonite 3
> Flint 23
>
> In oxidation a clear glaze with a chun translucent blue, especially at
> lower temperatures. In reduction a semi-clear, blue-grey glaze.
>
> #148 wide-firing clear base glaze
>
> Feldspar (soda)** 38
> Whiting 14
> Zinc Oxide 12
> Ball Clay 6
> Flint 30
>
> A semi clear 'chun' glaze. In oxidation a semi-translucent, delicate
> 'chun' glaze more clear in reduction.
>
>
> *There are many calcium borate frits. The Careful Potter keeps the most
> popular one in her glaze pantry, and tries all when testing a new, but
> unspecific glaze.
>
> ** The convention is that where it simply says "FELDSPAR" in a recipe,
> potash spar is meant. Note here that when a soda spar is meant it SAYS S=
O.
>
> All these glazes should be tested, obviously some in blends, and I expect
> the desired effect will be achieved.
>
> Thickness of application matters in achieving the desired effect in this
> case, so thickness should be tested as well.
>
>
> _________________________________________________________________________=
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