Don Jung on wed 12 nov 97
Ron,
thanks for checking these glazes...you have a good eye for these
things. I checked and behold, you are correct. The original recipe is
below (I hope it comes out to 100). The one I posted earlier was a
modification which substituted Wollastonite for Whiting and made the
numbers go off by a bit. It's now corrected.
As for the expansion, they are lower than the rest of our glazes, but I
find our clays and slips work best with clears that are lower in
expansion. Clears seem to be more prone to crazing (as well as show
them easier)...I think the extra ingredients in colored glazes also give
them a wider range of 'flexibility'. Expansion around 65 seems to work
for us. The one that shivered was under 60, maybe even under 55.
I also agree with someone else's post that they should try out Tony
Hansen's clear at www.ceramicsoftware.com/education/glaze/cone6.htm.
For those without a web browser I've included the recipe as well. I've
tested it with mixed results (some cloudiness still). I'll test it
again when we do up some more glazes. :)
take care
Don Jung
in sunny Vancouver , yep that's right, sunny.
----------------------------Original message----------------------------
Toni -
I am not enough of a glaze chemist to be able to explain that "clouding"
problem at 5:30 in the morning, but I do know that the following glaze
works very well for me at Cone 6.
Patti's Crystal Clear ^5-7
Gerstley Borate 10.5
Whiting 4.0
Neph Sy 15.0
Kaolin 5.0
Flint 15.5
I got the glaze from CLAYART some time ago. It was posted by Janice
Lipuma from Lexington KY.
--
David McBeth, MFA
Associate Professor of Art and Art Ed
330 C Gooch Hall
University of Tennessee at Martin
Martin, TN 38238
901-587-7416
http://fmc.utm.edu/~dmcbeth/dmcbeth.htm
----------------------- from Tony Hansen's web page
----------------------------
CLEAR 2617
KONA F-4 FELDSPAR 46.00 CaO 0.464*
GERSTLEY BORATE 30.00 MgO 0.002*
EPK KAOLIN 13.00 K2O 0.106*
FLINT 11.00 Na2O 0.427*
======== Fe2O3 0.003
100.00 TiO2 0.002
Si:Al 5.836 B2O3 1.000
SiB:Al 7.486 Al2O3 0.606
Expan 7.611 SiO2 3.537
Ron Roy wrote
-------------------------------------------------------------
Did you see the post by Don Jung? - he mentions having had a shivering
problem with this glaze. I think you are not having a problem because
you
are using it thinly and on porcelain. If you used it thicker on
stoneware
....8< snip
.... I just checked the glazes than Don posted - Patti's Crystal clear
and
Clear 4321
(Don - the total for Patti's is only 96.48 - am I working with a full
deck?)
My limits say they are durable glazes but the expansion is a bit low on
....8< snip
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