Hank Murrow on wed 15 nov 00
>Dawn wrote;
>I found some beautiful clay near my home here in Tennessee. I am new to
>pottery and was wondering how I might determine how hot to fire this clay. I
>have an electric kiln. This clay is golden colored and it threw an nice
>cylinder. I am just afraid I will melt it all over my kiln. Looked in the
>archives and got the name of the book, The Potter's Alternative. Is this a
>good resource or can anyone recommend any other?
Dear Dawn;
Harry's book is a wonderful compendium of tool plans and instructions on
how to build them. However, if you are trying new materials to determine
how they might fit with each other and what they contribute; I reccommend
Ian Currie's book, "Revealing Glazes", available in about a week by credit
card from the author's website:
http://ian.currie.to/
i have found it very useful, especially when dealing with local materials
that lack an empirical formula or an analysis. That said, Wwhy don't you
make some bars of this clay about 12 centimeters long and say 3/8" thick.
mark 10 cms off on a line down the middle, fire one to bisque propped up on
each end by a short kiln post so you can see if it sags. If not(my quess),
then try at C/1, if not, try at C/5. you might have to go even higher; but
probably not. if you are still nervous about your kiln, just do these tests
on a clay platter or plate to protect the shelf.
Good Hunting! Hank in Eugene
Cindy Strnad on wed 15 nov 00
Dawn,
I suggest you make some plates (nothing fancy--just disks) out of a known
clay, and fire small pieces made of your home-dug clay on those plates. Most
of the "wild" clay you find will be low-fire, so start with ^06 or so, and
work up or down from there.
You may also find that adding a bit of sand for temper will improve the
clay. Ancient potters often did this, I'm told. I've tried it with clay from
near here (just sand from my daughter's sand box), and the sand does make it
a lot easier to work with.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Daraburn@AOL.COM on wed 15 nov 00
I found some beautiful clay near my home here in Tennessee. I am new to
pottery and was wondering how I might determine how hot to fire this clay. I
have an electric kiln. This clay is golden colored and it threw an nice
cylinder. I am just afraid I will melt it all over my kiln. Looked in the
archives and got the name of the book, The Potter's Alternative. Is this a
good resource or can anyone recommend any other?
Thanks,
Dawn
Jeff Lawrence on thu 16 nov 00
Dawn was soliciting opinions on local clay testing ...
Hi Dawn,
It's fun stuff and successive tests up the cone chart are probably the most
sensible.
My less-sensible approach was ask a cone 10 potter to fire a sample in his
firings (in an old bowl to protect shelves). I got green-black glass, frozen
in mid-boil. Same thing with cone 6 -- Dali-ville with cup-like shapes
caught as they writhed toward the same melted fate.
I haven't found any local clays that don't behave in firing to cone 04.
Note: Some clays have little granules of gypsum that will reduce the pot to
shards during the month or so after firing. At the time, I was convinced
that one was a bad choice for my son's day-care class project ... but in
retrospect, perhaps those pots were good candidates for self-destructing
pottery.
Jeff Lawrence ph. 505-753-5913
Sun Dagger Design fx. 505-753-8074
18496 US HWY 285/84 jml@sundagger.com
Espanola, NM 87532 www.sundagger.com
ps If you can find the Potters Alternative, grab it.
Ann Brink on thu 16 nov 00
Sometimes people give me bags of clay saying "My son/daughter used to take
ceramics in school and left this years ago, can you use it?". So when I
want to test an unknown clay I make a little "T" shaped figure, and fire it
on a scrap of other clay or old kiln shelf, in my next high glaze firing.
Or sometimes I throw a tiny bowl with a horizontal rim and set it on
something as well. If you glaze at ^5 or so, you'd still not be sure it
would go to ^10, and would have to test.
I've never heard of a clay melting at bisque temperatures, so you could put
your pot in your next bisque load and see how it acts...it may sound and
feel mature at earthenware temp.
Good luck,
Ann Brink in CA
----- Original Message -----
From:
To:
Sent: Wednesday, November 15, 2000 1:58 PM
Subject: How to fire local clay?
> I found some beautiful clay near my home here in Tennessee. I am new to
> pottery and was wondering how I might determine how hot to fire this clay.
I
> have an electric kiln. This clay is golden colored and it threw an nice
> cylinder. I am just afraid I will melt it all over my kiln. Looked in
the
> archives and got the name of the book, The Potter's Alternative. Is this
a
> good resource or can anyone recommend any other?
> Thanks,
> Dawn
>
>
____________________________________________________________________________
__
> 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
melpots@pclink.com.
>
Snail Scott on thu 16 nov 00
Definitely use a scrap shelf or slab of known clay
underneath it, and you might want to start your tests
quite low in temperature. Some native clays turn to
slip-glaze at temps as low as ^06.
-Snail
At 07:01 PM 11/15/00 -0800, you wrote:
>>Dawn wrote;
>
>>I found some beautiful clay near my home here in Tennessee. I am new to
>>pottery and was wondering how I might determine how hot to fire this
clay. I
>>have an electric kiln. This clay is golden colored and it threw an nice
>>cylinder. I am just afraid I will melt it all over my kiln. Looked in the
>>archives and got the name of the book, The Potter's Alternative. Is this a
>>good resource or can anyone recommend any other?
>
>
>Dear Dawn;
>
>Harry's book is a wonderful compendium of tool plans and instructions on
>how to build them. However, if you are trying new materials to determine
>how they might fit with each other and what they contribute; I reccommend
>Ian Currie's book, "Revealing Glazes", available in about a week by credit
>card from the author's website:
>
>http://ian.currie.to/
>
>i have found it very useful, especially when dealing with local materials
>that lack an empirical formula or an analysis. That said, Wwhy don't you
>make some bars of this clay about 12 centimeters long and say 3/8" thick.
>mark 10 cms off on a line down the middle, fire one to bisque propped up on
>each end by a short kiln post so you can see if it sags. If not(my quess),
>then try at C/1, if not, try at C/5. you might have to go even higher; but
>probably not. if you are still nervous about your kiln, just do these tests
>on a clay platter or plate to protect the shelf.
>Good Hunting! Hank in Eugene
>
>___________________________________________________________________________
___
>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
melpots@pclink.com.
>
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