Gaydos, Frank on mon 13 apr 98
Hello clayarters;
I have a problem and need some help.
We are offering a colored clay workshop this summer and originally
wanted to use the cone 6 clay that the instructor was familiar with.
Fine. But the instructor decided at the last minute to change the firing
temperature to the same as we usually use in the studio,that is, cone
04. She did this so the students will be able to use what they learn
after the workshop is over.However, I do not have enough time to test
clay bodies that have no grog and take pigments well. The question is:
Does anyone have a good earthenware body that is mature at cone 04, has
no grog, and takes pigments well? It will be used for slab
construction.The lack of grog is due to the fact they will be sanding a
lot.
I hope I dont offend the claybody papacy.
TIA
Frank Gaydos
Community College of Philadelphia
Fgaydos@ccp.cc.pa.us
Vince Pitelka on tue 14 apr 98
>Does anyone have a good earthenware body that is mature at cone 04, has
>no grog, and takes pigments well? It will be used for slab
>construction.The lack of grog is due to the fact they will be sanding a
>lot.
Frank -
For the last 13 years I have used the following claybody for most of my
colored clay work, primarily large, complex architectural vessels and
sculpture with laminated colored clay pattern work. It is gritless, fires
pure white, takes colors well, works great for throwing and handbuilding,
joins aggressively, very few problems in drying and firing. I usually fire
it to 04 or 03, but have also fired it as high as cone 3. Above cone 1 it
is quite vitreous, suitable for functional ware. It is quite close to a
porcelain body, but more heavily loaded with soda spar. It does not fit
your normal whiteware body formulas, but as I said, I have been using it for
13 years, with no complaints at all. I love it. How's that for a testimonial.
Vince's Low-Fire Whiteware Body - cone 05-03 - denser than a talc body -
suitable for both functional work and sculpture. Fire functional work at
least to cone 03 for density and durability. Can fire as high as cone 3 (or
higher?).
OM4 Ball Clay ---------------- 36
Kaolin ---------------------------- 32 (I prefer to use tile-6, but EPK
works fine.
Custer or G200 Feldspar - 10
Flint ------------------------------ 12
Nepheline Syenite ---------- 10
Total ---------------------------- 100
Good luck -
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Tony Hansen on thu 16 apr 98
>Does anyone have a good earthenware body that is mature at cone 04, has
>no grog, and takes pigments well? It will be used for slab
>construction.The lack of grog is due to the fact they will be sanding a
>lot.
Non fritted cone 04 bodies have 10% porosity or better so they are
no where near vitreous. Since little glass develops they don't repond
to color additions nearly as well. It will be very difficult.
The typicall 04 white is 50% ball clay and 50% talc. Try that.
--
T o n y H a n s e n thansen@digitalfire.com
Don't fight the glaze dragon alone
INSIGHT, Magic of Fire at http://digitalfire.com
Vince Pitelka on sat 18 apr 98
Regarding my favorite whiteware body which I posted to the list several days
ago, I received a post from Tony Hansen suggesting that glazes would tend to
craze badly on this body (see below). It was careless of me to suggest that
this body is suitable for functional work, without pointing out that the
clear glazes I have used on it do tend to craze at all temperatures. That
was a serious oversight on my part.
I have colored clay mugs made with this claybody, fired to cone 1, which I
have used for years. The clear glaze is badly crazed. Crazing is a flaw.
Avoid crazing. Eliminate crazing whenever you can. But, those of us
working with colored clays have a whole set of other criteria to consider,
and most of my colored clay work is non-functional, so I do not worry about
crazing.
>> Vince's Low-Fire Whiteware Body - cone 05-03 - denser than a talc body -
>> suitable for both functional work and sculpture. Fire functional work at
>> least to cone 03 for density and durability. Can fire as high as cone 3 (or
>> higher?).
>> OM4 Ball Clay ---------------- 36
>> Kaolin ---------------------------- 32 (I prefer to use tile-6, but EPK
>> works fine.
>> Custer or G200 Feldspar - 10
>> Flint ------------------------------ 12
>> Nepheline Syenite ---------- 10
>
Tony's response:
>I did see your orginal post but hesitated to comment. It takes about
>50%
>feldspar to get a vitreous body at cone 6 and you have only 20% here. I
>suspect this body would go to cone 10. It certainly would be plastic
>with 68% clay. I'm not sure how you are not getting crazing since the
>talc is added to low fire bodies to dramatically increase their thermal
>expansion to make it easy to fit glazes.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Bill Aycock on sun 19 apr 98
The recent exchange involving Vince and Tony on this subject illustrates
several of the things that make this list, and the by-play in it- such a
delight.
1. Vince published the recipe for one of his whiteware bodies. Tony had
also put one out- apparently in response to the same query.
2. Tony checked the Vince body- said-" Hey- that is probably going to have
crazing problems"
3. Vince said- "you're right, but its for non-utilitarian, so?" and "I knew
that- sorry I didn't say something"
There are several VERY significant factors in play here.
Despite the recent put-down of some aspects of the use of "science"- and
the sloppy claims from some for the benefits of science, what Tony did was
the direct result of applied science by a knowledgeable practitioner- he
predicted a result, which was confirmed.
There was no name calling or snideness to any comments.
Both were involved in being helpful- which, considering the high level of
qualifications both have, is a lot for free.
And- this type of thing goes on a lot., and we expect it, despite the high
visibility of a couple of Characters that don't fit this mold.
Hey- It's nice-- Bill, about to be washed off Persimmon Hill.
At 10:01 AM 4/18/98 EDT, you wrote:
>----------------------------Original message----------------------------
>Regarding my favorite whiteware body which I posted to the list several days
>ago, I received a post from Tony Hansen suggesting that glazes would tend to
>craze badly on this body (see below). It was careless of me to suggest that
>this body is suitable for functional work, without pointing out that the
>clear glazes I have used on it do tend to craze at all temperatures. That
>was a serious oversight on my part.
>
>I have colored clay mugs made with this claybody, fired to cone 1, which I
>have used for years. The clear glaze is badly crazed. Crazing is a flaw.
>Avoid crazing. Eliminate crazing whenever you can. But, those of us
>working with colored clays have a whole set of other criteria to consider,
>and most of my colored clay work is non-functional, so I do not worry about
>crazing.
>
>>> Vince's Low-Fire Whiteware Body - cone 05-03 - denser than a talc body -
>>> suitable for both functional work and sculpture. Fire functional work at
>>> least to cone 03 for density and durability. Can fire as high as cone
3 (or
>>> higher?).
>>> OM4 Ball Clay ---------------- 36
>>> Kaolin ---------------------------- 32 (I prefer to use tile-6, but EPK
>>> works fine.
>>> Custer or G200 Feldspar - 10
>>> Flint ------------------------------ 12
>>> Nepheline Syenite ---------- 10
>>
>
>Tony's response:
>>I did see your orginal post but hesitated to comment. It takes about
>>50%
>>feldspar to get a vitreous body at cone 6 and you have only 20% here. I
>>suspect this body would go to cone 10. It certainly would be plastic
>>with 68% clay. I'm not sure how you are not getting crazing since the
>>talc is added to low fire bodies to dramatically increase their thermal
>>expansion to make it easy to fit glazes.
>
>- Vince
>
>Vince Pitelka - vpitelka@DeKalb.net
>Home 615/597-5376, work 615/597-6801, fax 615/597-6803
>Appalachian Center for Crafts
>Tennessee Technological University
>1560 Craft Center Drive, Smithville TN 37166
>
>
Bill Aycock --- Persimmon Hill
Woodville, Alabama, US 35776
(in the N.E. corner of the State)
W4BSG -- Grid EM64vr
baycock@HiWAAY.net
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