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calcined?

updated tue 30 sep 97

 

The Allens on sun 31 aug 97

Would someone explain how to calcine kaolin? In an open container? At what tem

Thanks for your help,

Carla Allen
ridgerun@scrtc.blue.net

stevemills on mon 1 sep 97

In a biscuitware bowl to 1000oC.
Steve

In message , The Allens writes
>----------------------------Original message----------------------------
>Would someone explain how to calcine kaolin? In an open container? At what te
>
>Thanks for your help,
>
>Carla Allen
>ridgerun@scrtc.blue.net
>

--
Steve Mills
@Bath Potters Supplies
Dorset Close
Bath
BA2 3RF
UK
Tel:(44) (0)1225 337046
Fax:(44) (0)1225 462712

Ric Swenson on sun 7 sep 97

>----------------------------Original message----------------------------
>Would someone explain how to calcine kaolin? In an open container? At
>what tem
>
>Thanks for your help,
>
>Carla Allen
>ridgerun@scrtc.blue.net


Carla,

I have been off the list, when our new fiber-optic phone and data system
was being put in on campus...then got back on...and our modem connections
failed. As a result am now wading through 590 messages....forgive me if I
missed the diffinitive answer to your post, already.

You might try this...

Use a bisque-fired, open bowl, fill it with dry kaolin, put it in cone 06 (
mas o menos) bisque fire along with rest of stuff.

VIOLA! (like magic)

"Calcined" Kaolin !

I believe that you only have to drive off the H2O in physical and
chemically combined forms..to calcine a material. Make sure you are
calcining something that has a PCE ...(Pyrometric Cone Equivalent) well
above the bisque temperature. Most raw materials we work with have melting
temperatures that are pretty high. Like cone 20 or 32.... Don't try to do
this with a really low fire frit, or you will have a big bowl of "glassy
stuff".

Calcining is like "pre-shrinking" the material...like jeans...in a way.

HTH

Ric

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
rswenson@bennington.edu "Standard Disclaimers Apply" "Opinions are my own."
Ric Swenson, Bennington College, Route 67 - A, Bennington, Vermont 05201
- 6001
802 442 - 5401 vox 4621 fax 4582 or direct fax 802 442 - 6164
********************************************************************************
****************

BCTanz on fri 12 sep 97

Calcining clay is very simple...place the material that you need to
calcine in a bisqued pot(it can be an old pot that cracked in a previous
firing) and fire in your next bisque firing. After unloading, transfer the
calcined material to an airtight container...glass works best...and
label/store with your glaze materials. Polyeurethene is not as efficient
since some moisture from the atmosphere can be reabsorbed through some plastics.
Hint: do same with zinc oxide...it will lessen the crawling problems
inherent in glazes containing zinc. Zinc is an oxide that has one of the
highest "coefficient of expansion" factors. Calcining removes the water
molecule from the emperical formula of your material and thus cuts down on
shrinkage.