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oven ware

updated thu 26 apr 12

 

Talbott on thu 24 jul 97

What will make stoneware cone 9/10 into true oven ware?

1ST ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summer 1997)
http://fmc.utm.edu/~dmcbeth/cag/naples.htm

Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
WBS Live Chat Room, Sat Nites 10 PM EDT, Private Room: Clayarters
E-MAIL: clupus@ime.net

Ric Swenson on fri 25 jul 97

>----------------------------Original message----------------------------
>What will make stoneware cone 9/10 into true oven ware?
>
> 1ST ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summer 1997)
> http://fmc.utm.edu/~dmcbeth/cag/naples.htm
>
> Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
> Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
> WBS Live Chat Room, Sat Nites 10 PM EDT, Private Room: Clayarters
> E-MAIL: clupus@ime.net


-----------reply---------

Dear Talbotts,

First.......Define "OVEN WARE"......? Oven proof?....Freezer to hot oven
proof?....Flameware....Stove top Safe? Microwaveable?....Oven
resistant?....... There are DEGREES of oven ware and your definition might
not be that used by others?

but....

Some of the possibilities ...(serious and not-so -serious included...) :)

1.) A Lithium based body and matching glaze fired to cone 12 or 14 on a L
O N G fire cycle. (I believe that somewhere on those 5 1/2" disks in the
desk drawer...over there...which I cannot access from my machine, I have a
formula or two for bodies that are pretty good. Colors are VERY limited.
Mental Picture: "Spodumene glazes") Recommend potters make Contact with
makers of low expansion minerals....like: Lithium Carbonate (Li2O3 + $),
Petalite (about 5-6% LiO2). Spodumene, (6% LiO2) or Lepidolite (3% LiO2)
or.....( the ever popular grad school question... what IS the fifth source
of Lithia for ceramics??? ANYONE??? yes folks...it's... ....Amblygonite !
(8% LiO2). The idea is that low expansion is needed.

2.) Read about Flameproof ware in Frank Hamer's book (p. 126 in my old
1975 first ed.) THE POTTER'S DICTIONARY OF MATERIALS AND
TECHNIQUES.....newer ed. may even have more info?
see also "Ovenware" p. 208 ibid. see also Casserole, p. 47-8.

3.) Under-fired terracotta is pretty oven-flame proof. .... a bitch to
clean however....

4.) To make your own body MORE oven resistant, a simple addition of 10% raw
Kyanite will improve MOST bodies...and your same glazes will still fit, for
the most part. (no guarantees on that one !....but I had very good results
at cone 6 and at cone 10)

5.) Pray.

6.) Lengthen your fire cycle and try to develop more Cristobalite from the
silica quartz form which has a higher coe (co-efficient of expansion) and
will take temperture changes better. Alpha/Beta Quartz inversion @ Hamer
p. 265-272 "Silica"...............( Or something like that....I'm quite
sure that will start a whole new discussion of the scientific explanation
of how that works....let the games begin!)

7.) Find a magician, high (or low) priest, or scorcerer to cast a spell on
your pots to make them ovenware.

That's all I can come up with until I unlock the key to all that stuff off
those old disks....

Regards,

Ric

Ric Swenson, Bennington College, Route 67 -A, Bennington, Vermont 05201-6001
802 442-5401 x 262 vox x 237 fax or dedicated fax 802 442-6164
email: rswenson@bennington.edu

Tony Hansen on sat 26 jul 97

> What will make stoneware cone 9/10 into true oven ware?

Low and linear thermal expansion mainly.

--
T o n y H a n s e n, I M C thansen@digitalfire.com

Ron Roy on sun 27 jul 97

One of the suggestions was to try and increase cristobalite in the body -
Exactly the opposite is true - eliminate it - the less the better and none
is best. Cristobalite goes through it's reversible expansion and
contraction at oven temperatures.

Use a clay with as little iron as possible if firing in reduction.

Make sure there is at least 10% spar in the body and enough refactories so
that it is not too tight.

Design your cassarols so that the form is round inside instead of flat
bottomed and straight sided.

If the ware is to be glazed make sure the glaze is just below crazing and
use the same glaze inside and out. If you must use two glazes -make them
have similar expansions. If no glaze is used -inside or out the problems
are much simplified.

I don't believe praying will help but testing will.


The following was one of many suggestions in answer to the question "What
will make stoneware cone 9/10 into true oven ware?"

>6.) Lengthen your fire cycle and try to develop more Cristobalite from the
>silica quartz form which has a higher coe (co-efficient of expansion) and
>will take temperture changes better. Alpha/Beta Quartz inversion @ Hamer
>p. 265-272 "Silica"...............( Or something like that....I'm quite
>sure that will start a whole new discussion of the scientific explanation
>of how that works....let the games begin!)

Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm

John Baymore on sun 27 jul 97

------------------
Ric S. left out one important point in his ......top ten...... list for
making ovenware:

8. Get product liability insurance in large amounts=21 :=7E)


Best,

.......................john


John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA

603-654-2752
JBaymore=40Compuserve.com

Ric Swenson on mon 28 jul 97

John,

Yes I did leave that one out.! .... and there is more....

I did make an error in saying that Cristobalite has a higher Alpha-Beta
inversion temperature than more familiar Quartz forms...(I must have been
thinking about Mullite and use in kiln shelves ..???? .....when in
doubt...keep mouth shut....and fingers OFF keyboard.!) My
apologies.....and thanks to Ron Roy for pointing out the error in a kind
post.

Oven-ware...making your casseroles more likely to survive oven use...I
should say involves a number of items. Shape of the piece curved not flat
sides...low iron content....and others than Ron Roy added are excellent
additions.

IF you advertise that your ware WILL take oven to tabletop use.... It had
better be able to do it. You may need insurance at that point ...(or need
to move because your reputation is in question? ...HA!)

If it was easy to do, everyone would have a body and glazes that did not
expand as heated and contract when cooled.

Corning Glass does an amazing job of standing up to the task....but then
they are NOT studio potters and their wares have their own special look ...
and feel. (I believe they have 6 or 7 lawyers that deal just with issues
of liability concerning oven proof products. I heard that from Herb Dann,
now retired, who was one of their design heads for many years.)

Ric



>----------------------------Original message----------------------------
>------------------
>Ric S. left out one important point in his ......top ten...... list for
>making ovenware:
>
>8. Get product liability insurance in large amounts! :~)
>
>
>Best,
>
>......................john
>
>
>John Baymore
>River Bend Pottery
>22 Riverbend Way
>Wilton, NH 03086 USA
>
>603-654-2752
>JBaymore@Compuserve.com

Ric Swenson, Bennington College, Route 67-A, Bennington, Vermont,
05201-6001 USA. telephone 802 442 - 5401 vox X 262 fax X 237
direct fax line
802 442 - 6164
rswenson@bennington.edu

Tony Hansen on tue 29 jul 97

> So, the average small studio potter, buying their clay premixed, wet from
> their supplier (laguna for me) really can't tell their customer that their
> ceramic ware is safe for oven use unless all of the above is
> tested/interpreted?

It's a tough question. Corning Ware spends millions to make ware
ovenproof,
many potters give no consideration to giving their ovenware any more
resistant
to thermal shock than their candle holders.
As Ron Roy said, there is no substitute for the
basics, ware of even cross section, glazes that fit properly, even
firing,
bodies of adequate maturity to eliminate cristobalite.

> We buy a bag of clay, throw a casserole dish, check
> appropriate firing temp, pick out or mix up a favorite glaze, watch that
> cone bend, cool kiln slowly and it should be ready to use. It is stoneware -
> that in itself leaves the impression that this will be a durable product.

Stoneware means hard and strong, it doesn't mean thermal shock
resistant. In
fact by its very nature, fired clay is one of the least thermal shock
resistant
materials there is.

> I don't think I want to know at
> this point that all the work I done for several years with this clay is
> somehow substandard.

Ware that I made 10 years ago is not as good as I am making now. I am
much more
aware of glaze fit issues, for example. I am downright ashamed of cone
10R iron
ware I made in the past. It is porous and expands with moisture, it is
so
weak I can tear it apart with my bare hands. I wish I could get it all
back
and apologize to the customers but I can't.

> If there is a glaze that doesn't seem to be fitting
> right, then I attempt to alter the glaze.

No way around this one, I agree. But you have to have a good way to test
the
fit to know if your alteration is doing what you want.

> Do I really want to mess with
> changing a premixed clay & shouldn't it already be tested before sale when I
> am buying from a big clay co?

It is not tested for ovenware applications, I am sure of that.
Can your supplier show you an expansion curve of the body fired to
the temperature and atmosphere you work at? A nice smooth line is a good
start.
--
T o n y H a n s e n, I M C thansen@digitalfire.com
=========================================================
INSIGHT5/Magic of Fire II demos at http://digitalfire.com

mel jacobson on wed 14 dec 11


i stopped making that sort of thing
about ten years ago.

it just did not seem worth it.
most modern american folks just do
not make hot dishes, casseroles any longer.

and, many that do, have no clue how to
use ceramics in the oven properly.

so.
i make a lovely shallow bowl and i sell
an aluminum foil cover for two cents,
that helps make it a casserole.
mel
i no longer sit around waiting for some
dork attorney to call me with a sad story
of mrs. nelson's casserole splitting and
sending hot grease on her legs.

hell, i even worry about folks putting
my fine t-pots on the stove to heat water.

my fear of a world being raised with folks
that do not know anything.
`you mean i have to pay for using a credit card?
like pay it back? ```
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html

Deborah Thuman on wed 25 apr 12


My solution is using mica clay. New Mexico Clay (and I assume others) =3D
sells a low-fire red clay with mica in it. In theory, you're supposed to =
=3D
be able to use pots made from mica clay over an open flame. I've never =3D
tested that out.=3D20

What I have done is: put the mica clay casserole in a cold oven and =3D
baked whatever it was. I've put the mica clay pot in a hot oven (425) =3D
and made great bread. The mica clay bean pot makes the best =3D
anti-werewolf potatoes. The only decent rice pudding I've ever made was =3D
in a mica clay pot.=3D20

Personally, I've never found oven ware that cooks as nicely as a mica =3D
clay pot. I glaze the inside so I don't have to worry about bits of food =
=3D
being trapped and also for easier clean up. The outside of the pot stays =
=3D
naked so the sparklies show. I put the mica pots in the dishwasher for =3D
clean up.=3D20

Mica clay makes great teapots. No worries about shocking the pot and =3D
watching it shatter.=3D20

Deb Thuman
http://debthumansblog.blogspot.com
http://www.etsy.com/shop.php?user_ie=3D3D5888059
http://www.facebook.com/pages/Deb-Thumans-Art-Page/167529715986

Robert Harris on wed 25 apr 12


What on earth are anti-werewolf potatoes?

Do you put a silver dime in them (shades of the silver sixpenny bit in
Christmas pudding)?

Robert

On Wed, Apr 25, 2012 at 9:04 AM, Deborah Thuman wrot=
=3D
e:
> My solution is using mica clay. New Mexico Clay (and I assume others) sel=
=3D
ls a low-fire red clay with mica in it. In theory, you're supposed to be ab=
=3D
le to use pots made from mica clay over an open flame. I've never tested th=
=3D
at out.
>
> What I have done is: put the mica clay casserole in a cold oven and baked=
=3D
whatever it was. I've put the mica clay pot in a hot oven (425) and made g=
=3D
reat bread. The mica clay bean pot makes the best anti-werewolf potatoes. T=
=3D
he only decent rice pudding I've ever made was in a mica clay pot.
>
> Personally, I've never found oven ware that cooks as nicely as a mica cla=
=3D
y pot. I glaze the inside so I don't have to worry about bits of food being=
=3D
trapped and also for easier clean up. The outside of the pot stays naked s=
=3D
o the sparklies show. I put the mica pots in the dishwasher for clean up.
>
> Mica clay makes great teapots. No worries about shocking the pot and watc=
=3D
hing it shatter.
>
> Deb Thuman
> http://debthumansblog.blogspot.com
> http://www.etsy.com/shop.php?user_ie=3D3D5888059
> http://www.facebook.com/pages/Deb-Thumans-Art-Page/167529715986



--=3D20
----------------------------------------------------------

Steve Mills on wed 25 apr 12


Maybe they bite back!

Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my iPod


On 25 Apr 2012, at 15:21, Robert Harris wrote:

> What on earth are anti-werewolf potatoes?
>=3D20
> Do you put a silver dime in them (shades of the silver sixpenny bit in
> Christmas pudding)?
>=3D20
> Robert
>=3D20
> On Wed, Apr 25, 2012 at 9:04 AM, Deborah Thuman wr=
o=3D
te:
>> My solution is using mica clay. New Mexico Clay (and I assume others) se=
l=3D
ls a low-fire red clay with mica in it. In theory, you're supposed to be ab=
l=3D
e to use pots made from mica clay over an open flame. I've never tested tha=
t=3D
out.
>>=3D20
>> What I have done is: put the mica clay casserole in a cold oven and bake=
d=3D
whatever it was. I've put the mica clay pot in a hot oven (425) and made g=
r=3D
eat bread. The mica clay bean pot makes the best anti-werewolf potatoes. Th=
e=3D
only decent rice pudding I've ever made was in a mica clay pot.
>>=3D20
>> Personally, I've never found oven ware that cooks as nicely as a mica cl=
a=3D
y pot. I glaze the inside so I don't have to worry about bits of food being=
t=3D
rapped and also for easier clean up. The outside of the pot stays naked so =
t=3D
he sparklies show. I put the mica pots in the dishwasher for clean up.
>>=3D20
>> Mica clay makes great teapots. No worries about shocking the pot and wat=
c=3D
hing it shatter.
>>=3D20
>> Deb Thuman
>> http://debthumansblog.blogspot.com
>> http://www.etsy.com/shop.php?user_ie=3D3D5888059
>> http://www.facebook.com/pages/Deb-Thumans-Art-Page/167529715986
>=3D20
>=3D20
>=3D20
> --=3D20
> ----------------------------------------------------------