Arkham on sat 13 dec 97
hello mudites... another question (i totally missed the thread on eutectic
slips i posted a while back, if indeed it generated response, but i thank any
of you who did respond anyway sorry i missed it, it just never showed up)
new question: i have thrown a slew of apx 14-16" bowls with depths any where
from 3-6"..( to be christmas gifts). i guess they are on the more shallow
side. i use a raku clay from bennett pottery out of ocoee, florida (miller clay
# 200) i add nothing to the clay (ie: kianite or something) .. my problem is
as alot of people have (i HOPE) is te breakage or severe cracking of the
bowls... i fire to about 1850 + or - dependong on the glaze. i do it rather
slowly 45 min + or - ... i reduce as fast as i can (from kiln to bin) in a
hole in the ground covered by a large lid, air tight as possible ( very, very
little smoke escapes) let it cool anywhere from 25- 45 minites... before
opening (BUT if i dont burp, any glaze with any copper tends to go copper penny
totally and the crackle glazes are not as near as effective... but they they
(the bowl) still tend to crack... uuuuuuuugh.... =(
so if i get a non broken bowl its so copper that it looks like a darn giant
penny or just a crackle-less glaze.... is there a happy medium.. the clay is
very groggy (can hardly wake it... ) finished vessle is just over a .25" thick
at its thinest..... would like any suggestions (besides typing school) any one
might be able to offer..
thanking in advance,
sean clinton
vero beach, florida
//at an opening tonight sold enough to pay co-op rent through march
YES!!!!!!!//
Dannon Rhudy on sun 14 dec 97
----------------------------Original
new question: i have thrown a slew of apx 14-16" bowls with depths
any where
from 3-6".. problem is
.......e breakage or severe cracking of the
bowls...
--------------------------------------
It was difficult to understand from your post whether you are
makking a connection between the cracking of the bowls with the
"burping" of the smoking chamber. It seems unlikely that that
would be a cause of cracking.
What method are you using to lift the pieces from the kiln? Do
you use traditional tongs? This can cause cracking of large
flat-ish forms. Are the bowls footed? If not, and you fire
directly on the kiln shelf, the likelihood of cracking is
increased. Where are the cracks? Could it be that the base
is heating up much faster than the edge(s)?
I have fired many large, shallow bowl forms without cracking
them, and the claybody did not seem to matter - I've used
stoneware, porcelain, raku clays - whatever. I fire wide shallow
pieces supported by a couple of bricks placed on the
shelf; I lift them out with a tool shaped about like a two-
prong pitchfork, so that they can be lifted from beneath and
not by the edge. That method seems to work well.
If your glaze is too coppery, reduce the amount of copper in
the glaze, or change glazes, or fire more quickly, or to a
slightly lower temperature, or take a little more time to get into
the smoke chamber. In short, if what you are doing is failing
or disappointing you on a regular basis, change something.
Continuing to do more of the same, no matter how carefully you
do it, will produce the same unsatisfactory results.
You will no doubt have additional responses to your problem.
Think about what seems logically useful to you, and begin to
make some changes. If one does not work, another or a combination
of changes, likely will.
Dannon Rhudy
potter@koyote.com
| |
|
