Bacia Edelman on fri 24 oct 97
Dear Colleagues:
A very kind potter who is also an area high school art teacher has built a
wood-firing kiln and I am invited to try some of my own work in his firing
next week.
My concern is that two pieces with a cobalt wash, now bisqued, might cause
the cobalt to migrate, even if covered with a glaze, to other work in the
kiln. Details follow.
Since I have become a hand-builder, and a lot of the pieces are
labor-intensive, I have thrown a few items from a white stoneware
recommended by the kind potter and a few from some very old high-fire
porcelain, which incidentally throws beautifully. I have maybe 13 to 15
pieces to offer to the vagaries of the kiln.
Two deeply-textured hand-built porcelain forms invited an oxide wash, and I
decided on cobalt, mixed with some Ball clay and 2% bentonite, which I
applied to the bone-dry work and when dry, rubbed back to the depressions
with steel wool. I fired them with a thrown white stoneware jug in a very
small Paragon test kiln, as that was all the raw ware I had left. The
cobalt made smudges all over the jug and inside the porcelain textured
forms. Since I was wearing rubber gloves when I used the steel wool and may
have still had them on when stacking the little kiln, that may be the reason
for the smudges. The shelf was not affected. I washed the 3 pots hard, but
the plain jug still shows traces of cobalt smudge. That won't bother me,
but what if it bothers all the other folks' works in the vicinity. I have
never seen the kiln; it is not an anagama, but a Western style kiln, and I
think it may be as large as 100 cubic feet. I believe the potter salts a
bit at the end of the firing. My plan for glazing may include some of the
carbon-trap or shino glazes in Jack Troy's book and some flashing washes
from John Baymore.
This invitation is a one-time thing; a dream. It is not within the realm of
possibilities for me to build any sort of kiln, and I don't want to be the
cause of trouble for others. Can anyone give me a guess as to what would
happen if I put glaze on the stained pieces, or don't put any glaze on the
outside and see if a shino or carbon trap on the inside will cause a blush
on the outside?
Also, any suggestions for transporting already glazed work in a car? ( I
mean how to protect the pieces without removing glaze in transit.)
This got pretty long, sorry. Thanks in advance. Bacia Edelman Madison,
Wisconsin (cold and rainy with the tang of winter)
Jennifer Boyer on sat 25 oct 97
Hi Bacia,
I've been using cobalt wash over my glaze in a gas fired kiln firing to a
neutral cone 10 for many many years and have never had the cobalt migrate
to another pot. My guess is that you had smudges that you didnt' know about
which is very easy to do woth cobalt since it's so strong. I wouldn't
worry... you might try waxing over glaze wash, protrusions and rims to
transport the pots, but if you do, don't wrap with bubble wrap, since it
tends to stick to wax and pull away the wax and what's under it when you
unwrap the pot.
Jennifer in VT
>----------------------------Original message----------------------------
>
>Dear Colleagues:
> A very kind potter who is also an area high school art teacher has built a
>wood-firing kiln and I am invited to try some of my own work in his firing
>next week.
>
>My concern is that two pieces with a cobalt wash, now bisqued, might cause
>the cobalt to migrate, even if covered with a glaze, to other work in the
>kiln. Details follow.
>
>Since I have become a hand-builder, and a lot of the pieces are
>labor-intensive, I have thrown a few items from a white stoneware
>recommended by the kind potter and a few from some very old high-fire
>porcelain, which incidentally throws beautifully. I have maybe 13 to 15
>pieces to offer to the vagaries of the kiln.
>
>
>Two deeply-textured hand-built porcelain forms invited an oxide wash, and I
>decided on cobalt, mixed with some Ball clay and 2% bentonite, which I
>applied to the bone-dry work and when dry, rubbed back to the depressions
>with steel wool. I fired them with a thrown white stoneware jug in a very
>small Paragon test kiln, as that was all the raw ware I had left. The
>cobalt made smudges all over the jug and inside the porcelain textured
>forms. Since I was wearing rubber gloves when I used the steel wool and may
>have still had them on when stacking the little kiln, that may be the reason
>for the smudges. The shelf was not affected. I washed the 3 pots hard, but
>the plain jug still shows traces of cobalt smudge. That won't bother me,
>but what if it bothers all the other folks' works in the vicinity. I have
>never seen the kiln; it is not an anagama, but a Western style kiln, and I
>think it may be as large as 100 cubic feet. I believe the potter salts a
>bit at the end of the firing. My plan for glazing may include some of the
>carbon-trap or shino glazes in Jack Troy's book and some flashing washes
>from John Baymore.
>
>This invitation is a one-time thing; a dream. It is not within the realm of
>possibilities for me to build any sort of kiln, and I don't want to be the
>cause of trouble for others. Can anyone give me a guess as to what would
>happen if I put glaze on the stained pieces, or don't put any glaze on the
>outside and see if a shino or carbon trap on the inside will cause a blush
>on the outside?
>
>Also, any suggestions for transporting already glazed work in a car? ( I
>mean how to protect the pieces without removing glaze in transit.)
>
>This got pretty long, sorry. Thanks in advance. Bacia Edelman Madison,
>Wisconsin (cold and rainy with the tang of winter)
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer
Thistle Hill Pottery
Montpelier, Vt. 05602
jboyer@plainfield.bypass.com
ret on sat 25 oct 97
On Fri, 24 Oct 1997, Dannon Rhudy wrote:
> ----------------------------Original message----------------------------
>
> .......Also, any suggestions for transporting already glazed work
> in a car? ( I
> mean how to protect the pieces without removing glaze in transit.)
>
Have you tried adding a bit of Golden Syrup" or other glue to the glaze?>
Elke>
Barbara Lewis on sat 25 oct 97
I have also used dry cleaning bags wrapped around glazed work with no glaze
coming off. Barbara Lewis
blewis@crosslink.net
At 01:01 PM 10/24/97 EDT, you wrote:
>----------------------------Original message----------------------------
>
>.......Also, any suggestions for transporting already glazed work
>in a car? ( I
>mean how to protect the pieces without removing glaze in transit.)
>
>...........
>
>Bacia,
>
>If I need to transport glazed pieces, I usually just wrap them
>in paper towel, pack newspaper around. I have shipped them that
>way, even, and not had difficulties. However, some glazes
>flake off much more easily than others. You can re-bisque the
>pots after glazing, and you should find that the glaze stays on
>quite well for travel to the wood kiln.
>
>Dannon Rhudy
>potter@koyote.com
>
Craig Martell on sat 25 oct 97
Hi:
The unglazed pieces may cause a problem from fuming if salt is introduced
into the kiln. With no flux or silica to bond the cobalt to piece, it can
be transported by the salt vapor. I would suggest placing the pieces close
to the exit flue, and the cobalt should vacate the kiln with little or no
effect on other pieces. I would think that the pieces coated with a glaze
will not cause a problem.
If you can raw glaze your work, you could bisque the piece with the glazes
applied and this would prevent any harm during transport. You could also
bisque fire, glaze, and bisque again to a lower temp. I don't know how far
you have to transport the pots, but you could just pack them really
carefully and take a small amount of glaze with you to touch up any problem
areas. Drive carefully!
regards, Craig Martell-Oregon
Paul Lewing on sat 25 oct 97
Bacia,
A friend and I once had a makeshift studio for 9 months, where we had
no glaze kiln of our own. In fact, we made and bisqued the pots in
one place and took them to another house to glaze them. We glazed the
pots, then dipped the rims and any projections like handles and spouts
in hot wax. We then wrapped them loosely in paper and took them
across town and carried them down a flight of stairs to a friend's
kiln to fire. This kept the glazes from chipping pretty well, but we
also always took small jars of the glazes along to touch up. Oh, the
things we'll do to continue potting and avoid getting a real job!
Paul Lewing, Seattle
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