Clay on sun 9 mar 97
RED Art?
I don't know it is a true story or not ? Can you tell me?
There is one customer said that red art is unstable . & one time there is a
clay company been using it and come out the result that batch become 2 cones
lower than it use to be.
Thanks god that they leave a notes to all thier customer.
Unfortunatly, my friend got her clay from another distrbuter(that have the
notes which told her that after she find out herself) & she got a whole kiln
of overfiring plate.
Anyway nobody to blame on,but is the clay unstable that's I am interested in.
any body please?
At 08:54 AM 3/7/97 EST, you wrote:
>----------------------------Original message----------------------------
>>They are still quite strong however. Redart, the most well known terra cotta
>>clay in North America, has a porosity of 9% at cone 04 according to the
>>manufacturer. Working in low fire means accepting porous ware, I know of know
>>way to make a workable body from Redart that will come anywhere close to
>>vitrifying at cone 04?
>
>Tony, I didn't mean to imply that the body was vitrified. Perhaps I should
>have qualified "tight at 05". . I've had experience with bodies that are
>mature around 05 and do not easily accept a good glaze coat, expecially in
>thin-walled areas. It isn't vitrified , but the porosity is quite reduced.
>
>Linda
>Linda Arbuckle
>Associate Professor, Graduate Coordinator
>University of Florida, Box 115801, Gainesville, FL 32611-5801
>e-mail: Linda Arbuckle@ufl.edu
>
Tony Hansen on mon 10 mar 97
> There is one customer said that red art is unstable . & one time there is a
> clay company been using it and come out the result that batch become 2 cones
> lower than it use to be.
> Anyway nobody to blame on,but is the clay unstable that's I am interested in.
We've encountered truckloads of kaolin and ball clay in the last two
years with
much more variation than this. The trick is to use a clay recipe that
calls
on multiple sources of each clay type, two or three kaolins, two or
three
feldspars, etc. and monitor the materials and blends closely and
compensate
when changes occur. Another reason for using prepared clays.
If the above recipe had some flux it could be adjusted to compensate for
the change in Redart.
--
=================================================================
Tony Hansen, Plainsman
Ron Roy on mon 10 mar 97
>----------------------------Original message----------------------------
>RED Art?
>I don't know it is a true story or not ? Can you tell me?
>There is one customer said that red art is unstable . & one time there is a
>clay company been using it and come out the result that batch become 2 cones
>lower than it use to be.
>Thanks god that they leave a notes to all thier customer.
>Unfortunatly, my friend got her clay from another distrbuter(that have the
>notes which told her that after she find out herself) & she got a whole kiln
>of overfiring plate.
>Anyway nobody to blame on,but is the clay unstable that's I am interested in.
>
>any body please?
>At 08:54 AM 3/7/97 EST, you wrote:
The clay manufacturer I cunsult to tests each skid of clay that comes in so
we have records going back for at least 10 years. I happen to have the
records here at home from Jan 91 up toMay 96.
Tony said Cedar Hieghts says 9% at 04 which is a good average according to
our testing but - there is a variation and it changes within a shipment and
with each shipment. The highest porosity (cone 04 half down) was 10.8 and
the lowest was 6.5. As Tony was explaining it is imposible to make
vitrified low fired bodies with this type of clay because of the natural
variation in the refractoryness.
Many of the clay we use are variable - well no - let me say that in a
different way - they are all variable - somes are more consistant than
others.
If you are buying your clay or mixing it yourself - try to find a company
that tests their basic clays - even better - find one that tests their
bodies as well.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Kenneth D Westfall on tue 11 mar 97
A potter friend of mine got Red Art in January from Columbus Clay and has
see no ill affects from it. Columbus is not far from were Cedar Heights
is so I doubt they store larger volumes of RED ART. Therefore I would
say the clay was not mined very long ago. If you need more info call
Cedar Heights at (614) 682-7794 I am sure they will answer any question
concerning Red Art.
Kenneth Westfall
Pine Hill Pottery
potter-ken@juno.com
DON'T GET STUCK IN THE MUDPIES--K & T
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