Talbott on tue 9 dec 97
From what very little I know about crystalline glazes is that they
must first flow if the glaze is going to produce crystals.. so "no flow"
then "no crystals" so perhaps those temps are needed, as in our personal
glazes, before the glaze will flow... THE BEST GLAZES ARE THOSE THAT FLOW.
Those glazes that don't flow are "HUM DRUM".. we fire in reduction ^9/10 in
coppers, cobalts, chromium and the like... Sometimes just a difference of
45 degrees celsius make all the difference between an glaze that comes out
okay and one that is spectacular. I usually see ^9 half over through the
peep hole before shutting down the kiln. ...Marshall
>----------------------------Original message----------------------------
>I've seen and read about various crystal glaze recipes and all have been
>fired to cone 9 -10 except for one listed in the Answers to Potters
>Question book put out by Ceramics Monthly that lists a cone 5 recipe. Is
>there a reason(s) that crystal glazes are usually fired to cone 9-10 or
>can these recipes be modified to fire at a lower temperature, ie. cone
>5?
>Thanks, Max
101 CLAYART MUGS
2ND ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summer 1998)
E-MAIL ME FOR AN APPLICATION
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)
Clayarters' Live Chat Room, Fri & Sat Nites at 10 PM EDT & Sun at 1 PM EDT
http://webchat12.wbs.net/webchat3.so?Room=PRIVATE_Clayarters
---------------------------------------------------------------------
Rick Sherman on wed 10 dec 97
--------------------------Original message----------------------------
From what very little I know about crystalline glazes is that
they must first flow if the glaze is going to produce crystals.. so "no
flow" then "no crystals" so perhaps those temps are needed, as in our
personal glazes, before the glaze will flow... THE BEST GLAZES ARE
THOSE THAT FLOW. Those glazes that don't flow are "HUM DRUM".. we fire
in reduction ^9/10 in coppers, cobalts, chromium and the like...
Sometimes just a difference of 45 degrees celsius make all the
difference between an glaze that comes out okay and one that is
spectacular. I usually see ^9 half over through the peep hole before
shutting down the kiln. ...Marshall
----------------------response-----------------------------------------
Marshall: The flow factor is not always true. I have a good friend who
made beautiful crystal glazes which never required grinding. It was a
matter of experimentation until he got it right. He believed the
deciding factor was the cooling cycle. Yes, the glaze must be fluid
enough to allow for crystals to develop. However, it need not flow to
the bottom of the pot. It is mostly a matter of experimenting. I
admire those who take the time and effort.
RS
San Jose, CA
Vince Pitelka on wed 10 dec 97
> From what very little I know about crystalline glazes is that they
>must first flow if the glaze is going to produce crystals.. so "no flow"
>then "no crystals" so perhaps those temps are needed, as in our personal
>glazes, before the glaze will flow... THE BEST GLAZES ARE THOSE THAT FLOW.
As I understand it, glazes which are formulated for macrocrystalline effects
must also be quite low in alumina, which of course means lower viscosity,
and therefore a tendency to flow. Lower viscosity means more diffusion of
materials in the melt, and greater potential for recrystallization in the
initial cooling. If the glaze will not flow, the viscosity is too high for
good macrocrystalline effects.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
| |
|
