Eric Hansen on sat 12 feb 05
Clayarters: I have been sojourning with potters at UO/EMU Craft Center in E=
ugene and one of the grad students from the Fine Arts program a few years b=
ack developed a glaze which he named "Chinese Crackle" which is a mostly t=
hickly applied Neph Sy crackle clear with big, layered, round, "rotary" cry=
stals. Now the problem with this glaze is you can't use it in the Craft Cen=
ter studio because although the finished result are spectacular you cannot =
mix up a bucket for the glaze are for the students to use because it settle=
s into a solid rock within minutes. The teacher has tried all the usual add=
itions - bentonite, other clays, soda ash, veegum, and everything seems to =
alter the crystal pattern. I thought about ball milling EPK or XX Saggar si=
nce the bentonite problem, she said, was iron. What other means of suspensi=
on are there without altering this touchy glaze? It's mostly Neph Sy with a=
few other ground-stone type ingredients in it. All the info I have. Eric i=
n Eugene
--=20
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John Britt on sat 12 feb 05
Eric,
You need to use some Epsom salts to folcculate the batch. Nepheline
Syenite defloccultates.
A nice recipe out of my book is called:
CHINESE CRACKLE cone 10
Custer Feldspar 83.00
Silica 8.00
Whiting 9.00
For White add:
Zircopax 10.00
Also Ian Currie lists:
Snowflake Crystal cone 10
Custer Feldspar 80
Silica 10
Whiting 10
He recommends some (5%) bentonite.
Apply thickly.
Also the claybody will have a great effect on the crackle pattern.
Another method I have used for his glaze the glaze -straight Nepheline
Syentite - is to use it on a very groggy claybody and only mix what I want
to use immediately.
**(Of course this in not a balanced glaze and should not be used for
funtional work.)
Hope it helps,
John Britt
www.johnbrittpottery.com
Paul Herman on sat 12 feb 05
Eric,
Have you tried epsom salts, to flocculate the glaze?
I would use 0.5% in a "settler" glaze.
best,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: Eric Hansen
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Rotary Crystal cone 10 reduction glaze
>Date: Sat, Feb 12, 2005, 2:06 AM
>
> Clayarters: I have been sojourning with potters at UO/EMU Craft Center in
> Eugene and one of the grad students from the Fine Arts program a few years
> back developed a glaze which he named "Chinese Crackle" which is a mostly
> thickly applied Neph Sy crackle clear with big, layered, round, "rotary"
> crystals. Now the problem with this glaze is you can't use it in the Craft
> Center studio because although the finished result are spectacular you
> cannot mix up a bucket for the glaze are for the students to use because it
> settles into a solid rock within minutes. The teacher has tried all the
> usual additions - bentonite, other clays, soda ash, veegum, and everything
> seems to alter the crystal pattern. I thought about ball milling EPK or XX
> Saggar since the bentonite problem, she said, was iron. What other means of
> suspension are there without altering this touchy glaze? It's mostly Neph
> Sy with a few other ground-stone type ingredients in it. All the info I
> have. Eric in Eugene
> --
Jocelyn McAuley on sat 12 feb 05
Hi Eric,
I too used this glaze when I studied at UO. Chinese Crackle is one of
those old classics that has been around for decades. The UO ceramics
department keeps a bucket going every often or so, and just used 2%
bentonite. Another alternative might be epsom salts, CMC...
http://www.ceramicindustry.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2710,2703,00.html
However... even though this glaze is a beauty, I wouldn't recommend
having it be a craft center glaze! Why? This glaze routinely gets
discontinued in the UO ceramic dept for good reasons: it has to be
applied *thick* for the crystal patter to show up, and more and more
often you get students ridding that learning curve who throw this glaze
on the outside of their work where it will slide right off on to your
pretty nice shelves. There is also the debate about having a crackle
glaze that is only good on the inside of objects, ie bowls, which gets
used for food use (food safety of crackle glazes is probably a good one
to search for in the archives)... generally a no no.
The craft center is where I took my first ceramics lessons. After
moving over to the ceramics dept, did the real beauty of the craft
center come to light: the flawlessness of its glazes and firings. In
all the years I worked at the craft center, I *never* had a glaze run.
I *never* had a piece crack during firing. I don't mean to lecture, but
these are extrememly precious traits for a community ceramics studio.
I had quite the rude awakening at the ceramics dept! :)
perhaps this can be a special glaze that only the resident potters and
special others can use. Frank had a glaze or two like that when he was
resident potter there in the 90's. I don't think it would be a good
general glaze for everyone to use. Elitest, yes, but also practical.
btw- how has the move around at the craft center gone?
Jocelyn in rainy Eugene, having fond memories of her favorite glaze
combos... Woos Blue on top of shino!
Eric Hansen wrote:
> Clayarters: I have been sojourning with potters at UO/EMU Craft Center in Eugene
and one of the grad students from the Fine Arts program a few years back
developed
a glaze which he named "Chinese Crackle" which is a mostly thickly
applied Neph Sy
crackle clear with big, layered, round, "rotary" crystals. Now the
problem with this
glaze is you can't use it in the Craft Center studio because although
the finished
result are spectacular you cannot mix up a bucket for the glaze are for
the students
to use because it settles into a solid rock within minutes. The teacher
has tried all
the usual additions - bentonite, other clays, soda ash, veegum, and
everything seems
to alter the crystal pattern. I thought about ball milling EPK or XX
Saggar since the
bentonite problem, she said, was iron. What other means of suspension
are there without
altering this touchy glaze? It's mostly Neph Sy with a few other
ground-stone type
ingredients in it. All the info I have. Eric in Eugene
--
food: http://worlddomination.net/browniepoints
art: http://www.LucentArts.com
John Britt on sun 13 feb 05
Ileen,
No these are not real crystals. They are crackle patterns.
But ZnO is not the only oxide that will produce crystals. You can also get
crystals from in a glaze from iron oxide, manganese dioxide, calcium
oxide, etc. I guess we would have to distinguish macrocrystalline from
microcrystalline.
Hope that helps,
John Britt
www.johnbrittpottery.com
Ilene Mahler on sun 13 feb 05
are these real crystals with no zinc oxide..ilene in Conn
----- Original Message -----
From: "John Britt"
To:
Sent: Saturday, February 12, 2005 12:55 PM
Subject: Re: Rotary Crystal cone 10 reduction glaze
> Eric,
>
> You need to use some Epsom salts to folcculate the batch. Nepheline
> Syenite defloccultates.
>
> A nice recipe out of my book is called:
>
> CHINESE CRACKLE cone 10
>
>
> Custer Feldspar 83.00
> Silica 8.00
> Whiting 9.00
>
> For White add:
> Zircopax 10.00
>
>
>
>
> Also Ian Currie lists:
>
> Snowflake Crystal cone 10
>
> Custer Feldspar 80
> Silica 10
> Whiting 10
>
> He recommends some (5%) bentonite.
>
> Apply thickly.
>
> Also the claybody will have a great effect on the crackle pattern.
>
> Another method I have used for his glaze the glaze -straight Nepheline
> Syentite - is to use it on a very groggy claybody and only mix what I want
> to use immediately.
>
> **(Of course this in not a balanced glaze and should not be used for
> funtional work.)
>
> Hope it helps,
>
> John Britt
> www.johnbrittpottery.com
>
>
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