David Orser on thu 4 nov 99
---------- Forwarded message ----------
Date: Tue, 2 Nov 1999 21:31:03 -0500 (EST)
From: David Orser
To: mudpotter@hotmail.com
Subject: crystal
candace hello,
there was an article in CM a afew years back on crystal
glazes in redution. dont have it here but can check my files and get back
to you about that if you can't find.
i did a number ( 10 ?) of firingsin the 16 and 36 cubic ft olson
updrafts at mudflat studio in somerville ma. where i resided for the past
10 years (now
we're in maine). i was not reducing but firing neutrally, with little or
no flame present. i was also going for oilspot glazes, which worked well
in the bottom of the kiln.
for the crystal glaze, i was using one from the CM article, wait ithink i
have it here be right back: here it is:
BROOKE CRYSTAL #2
FRIT 3110 53.76
FLINT 19.36
ZINC OXIDE 26.88
ALSO: TITANIUM DIOX 8.60
COPPER CARB 2.15
OR
COBALT CARB 1.00
AND OF COURE YOU COULD TRY ANY OTHER COLORANT AND AMOUNTS.........
as for reduction, ive read tthat that can be couterprodutive to
crystal formation, but..... the cm article person was "striking" their
kiln- no no t hitting it.. but firing to temp doing the soak and letting
it cool to 1100 or so and the turning the gas back on and doing a
reduction then. the copper glazes were doing some almost raku luster
effects w/ the crystals still intact....interesting.
when i fired, i went up to temp, cone 9 or so and then brought it
back down by turn ing the gas down to a whisper, closing the damper way
down an monitoring w/ the pyrometer. since i don't really trust the
pyrometer @ high temps i put in a cone 1 (aprox the soaking temp) and
recorded what the pyro said at cone 1 on the way up and use that # on the
soak... i then held it there for 4-6 hours, and then shut down. got some
good results. the best crystals were on plates and bowls or other flat
surfaces. didn't get good results on vertical surfaces, tried very thick
glaze but to no avail.....
there's a great website to check out on this subject:
www.barra.se/stoneware/glasyrer/crystal.htm
good luck, david orser in MA and ME
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