Brad Sondahl on sat 2 nov 02
I was trying some recipes from Conrad's Contemporary Formulas (now a bit
dated actually--litharge, etc) First, I have to say that Conrad seemed
obsessed with crystalline glazes when writing the book, as nearly all
the pictures of glazes in the book were crystalline, but then I
sympathize with him, to some extent.
Anyway, I'm always interested in white glazes (the equivalent of vanilla
ice cream, not exciting but versatile) and here was a familiar name
attached to a white glaze. So here it is:
(Wildenhain White, cone 9-10 ox. or red.)
Custer feldspar 33.4
Dolomite 22.2
EPK 22.2
Flint 22.2
I like these simple formulas--seems likely the ancient potters would
have had some similar recipe from using primative balances to measure
with.
Anyway, it came out a nice buttery textured white, sort of semigloss. I
think it's probably a high magnesia matte. The nice thing about it is
that its whiteness comes about totally without opacifiers, making it a
dirt cheap glaze.
I don't have a use for it myself, but I'd recommend it. It might be good
for architectural and sculptural glazing, where gloss tends to detract.
I think it would be fine for functional pottery as well, if you were
looking for a similar finish. To brighten it, 5-10% zircopax probably
would do the trick nicely.
Brad Sondahl
--
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Ron Roy on sun 3 nov 02
The expansion of this glaze is right for most porcelains - if your body has
significant iron and/or is developing cristobalite - better do the fit
tests as the expansion may be too low.
The opaqueness and buttery feel are due to an over supply of MgO - not a
lot but it would be best to test it for stability if you are going to use
it as a liner.
Brad - try to scratch it with a spoon to see if it gets marked - if it does
try to get the marks off by rubbing with your finger. If they come off then
you do not have a serious marking problem.
Adding zirconium silicate will probably make it more prone to marking.
RR
>Anyway, I'm always interested in white glazes (the equivalent of vanilla
>ice cream, not exciting but versatile) and here was a familiar name
>attached to a white glaze. So here it is:
>(Wildenhain White, cone 9-10 ox. or red.)
>Custer feldspar 33.4
>Dolomite 22.2
>EPK 22.2
>Flint 22.2
>
>I like these simple formulas--seems likely the ancient potters would
>have had some similar recipe from using primative balances to measure
>with.
>Anyway, it came out a nice buttery textured white, sort of semigloss. I
>think it's probably a high magnesia matte. The nice thing about it is
>that its whiteness comes about totally without opacifiers, making it a
>dirt cheap glaze.
>I don't have a use for it myself, but I'd recommend it. It might be good
>for architectural and sculptural glazing, where gloss tends to detract.
>I think it would be fine for functional pottery as well, if you were
>looking for a similar finish. To brighten it, 5-10% zircopax probably
>would do the trick nicely.
>
>Brad Sondahl
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
June Perry on mon 4 nov 02
I ran this through My Insight 5.0 and like Ron, found it a bit low in
expansion. I did another version, using the same ingredient, but just by
lowering the dolomite and replacing it with whiting in order to raise the
expansion a bit and slight other variations.
I also wanted the Silica:Alumina ratio a bit lower. The Wildenhain recipe had
a ratio of 6.64 and my version is a little lower at 6.08, which should give a
nice matt without being shiny or dry.
With this much clay it would be good for raw glazing.
If anyone wants to be the test guinea pig :-), here's the recipe:
#8313 Matt White C 10 (this is also within C 10 limits, and within C 9
copper limits, but would need more silica to get it up to the 3.5 moles, the
minimum amount of Silica this program recommends for a C10 copper glaze)
33 Custer Feldspar
15 Dolomite
25 EPK
7 Whiting
20 Silica
Expansion 6.71, Ratio 6.08
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/index.html
Dwiggins, Sandra (NIH/NCI) on tue 5 nov 02
I don't think this glaze was for functional use. He did a lot of sculptural
work, used this glaze for that..... Not every glaze is a functional glaze,
guys!
Sandy
-----Original Message-----
From: June Perry [mailto:ShambhalaPottery@AOL.COM]
Sent: Monday, November 04, 2002 2:25 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Wildenhain's white glaze
I ran this through My Insight 5.0 and like Ron, found it a bit low in
expansion. I did another version, using the same ingredient, but just by
lowering the dolomite and replacing it with whiting in order to raise the
expansion a bit and slight other variations.
I also wanted the Silica:Alumina ratio a bit lower. The Wildenhain recipe
had
a ratio of 6.64 and my version is a little lower at 6.08, which should give
a
nice matt without being shiny or dry.
With this much clay it would be good for raw glazing.
If anyone wants to be the test guinea pig :-), here's the recipe:
#8313 Matt White C 10 (this is also within C 10 limits, and within C 9
copper limits, but would need more silica to get it up to the 3.5 moles, the
minimum amount of Silica this program recommends for a C10 copper glaze)
33 Custer Feldspar
15 Dolomite
25 EPK
7 Whiting
20 Silica
Expansion 6.71, Ratio 6.08
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/index.html
____________________________________________________________________________
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Wes Rolley on tue 5 nov 02
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At 02:24 PM 11/4/02 -0500, you wrote:
June, this hits me at just the right time. I need to find a good=20
semi-matte or matte white to balance some of the darker colors that I am=20
using. It is also opportune that I just returned from Ian Currie's=20
workshop (Nottingham, enjoyed it a lot). Now, a practical project to=20
reinforce what I learned.
I'll post results re: single firing and also on what I could find out about=
=20
the glaze using the grid method. Got the grid ready, just need to take the=
=20
time to go to the feed store for a good syringe.
>I ran this through My Insight 5.0 and like Ron, found it a bit low in
>expansion. I did another version, using the same ingredient, but just by
>lowering the dolomite and replacing it with whiting in order to raise the
>expansion a bit and slight other variations.
>I also wanted the Silica:Alumina ratio a bit lower. The Wildenhain recipe=
had
>a ratio of 6.64 and my version is a little lower at 6.08, which should give=
a
>nice matt without being shiny or dry.
>With this much clay it would be good for raw glazing.
>
>If anyone wants to be the test guinea pig :-), here's the recipe:
>
>#8313 Matt White C 10 (this is also within C 10 limits, and within C 9
>copper limits, but would need more silica to get it up to the 3.5 moles,=
the
>minimum amount of Silica this program recommends for a C10 copper glaze)
>
>33 Custer Feldspar
>15 Dolomite
>25 EPK
> 7 Whiting
>20 Silica
>
>Expansion 6.71, Ratio 6.08
>
>
>Regards,
>June Perry
>http://www.angelfire.com/art2/shambhalapottery/index.html
>
>___________________________________________________________________________=
___
>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=20
>melpots@pclink.com.
>
>
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"I find I have a great lot to learn =96 or unlearn. I seem to know far too=
=20
much and this knowledge obscures the really significant facts, but I am=20
getting on." -- Charles Rennie Mackintosh
Wesley C. Rolley
17211 Quail Court
Morgan Hill, CA 95037
wrolley@charter.net
(408)778-3024
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Wes Rolley on sun 10 nov 02
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At 02:24 PM 11/4/02 -0500, you wrote:
>With this much clay it would be good for raw glazing.
Just opened the kiln that AM and found that this is a true statement. The
glaze went on well and stuck very well. I was not wiping it off my hands
after moving the pots from the spray station to shelf to kiln.
I also found that it had to go on very thick to be white on my red
stoneware. Otherwise it was typically iron beige to grey.
Another interesting result was to layer a medium sized jar with a brown,
mostly redart glaze and to spray the Wilenhain on the rim/shoulder. As
good an imitation of ash deposit patterns as I have gotten in an electric.
Single fired, Electric. Cone 9 flat, Cone 10 touching at 6 o'clock.
Wes
Wes Rolley
17211 Quail Court
Morgan Hill, CA 95037
wrolley@charter.net
(408)778-3024
"Happiness is to be fully engaged in the activity that you believe in and,
if you are very good at it, well that's a bonus." -- Henry Moore
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June Perry on sun 10 nov 02
Wes, did you test the original or my altered, slighter matter version?
If you want it whiter, add either 4-5% tin oxide or 10-15% Zircopax. The
Zircopax has silica and might make it a bit less matt, but either one would
give you a whiter white over that iron bearing body.
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/index.html
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