Kate Johnson on wed 28 nov 01
Oh dear--there's an answer I didn't want to get!>
> Kate,
> I think you answered your own question "He does have me dry things with a
> hair dryer to about leather hard before taking them off the wheel, so I
can
> trim the bottom". I would suggest you at the very least run a wire under
> your pieces before you dry them with a hair dryer.
I'm not sure it would work with the procedure he teaches. We throw the pot
with thicker walls than we intend to finish with, then dry it enough to trim
it with a tool, while still turning. You can get some lovely, precise
effects that way...and I think if I used the wire under before trimming, the
trimming process would throw the pot off on the floor, wouldn't it?
You are drying everything
> but the bottom and are submitting you piece to stress and uneven dryness.
I can see how that could happen...I do try to dry the base to some extent
too, by aiming the dryer at the bottom and down inside the pot, but of
course you can't reach what's in contact with the wheel..
> I'm surprised they haven't cracked too. When you use the hair dryer you
are
> drying the outside while the inside clay has more moisture content. I used
> to use the hair dryer frequently and had quite a bit of warping, s-cracks
> and poor joins.
Well, that may be part of my problem, all right. What confuses me is that I
don't get warping or cracks when using white earthenware or raku clay, only
on the red or black, and I thought those were supposed to be more stable
than white...
I have indeed gotten a few s-cracks, but chalked it up to ineffecient
compression of the base...didn't think of uneven drying...
Now I slide the piece off the bat onto a piece of drywall,
> let it sit overnight uncovered ( living in the Seattle area I can do that)
> and the next morning I am ready for trimming.
>
Do you put it back on the wheel and re-center to trim? Is that the same
kind of trimming I'm referring to?
I'm sure that part of my problem is compounded by working at school--I can o
nly put in a few hours at a time, then have to wait until at LEAST the next
day, if not several days later...the accelerated classroom pace is probably
contributing to the difficulty...
Thank you for your help, I'll try to figure out how I could do that...
Best--Kate
claybair on wed 28 nov 01
Kate,
I think you answered your own question "He does have me dry things with a
hair dryer to about leather hard before taking them off the wheel, so I can
trim the bottom". I would suggest you at the very least run a wire under
your pieces before you dry them with a hair dryer. You are drying everything
but the bottom and are submitting you piece to stress and uneven dryness.
I'm surprised they haven't cracked too. When you use the hair dryer you are
drying the outside while the inside clay has more moisture content. I used
to use the hair dryer frequently and had quite a bit of warping, s-cracks
and poor joins. Now I slide the piece off the bat onto a piece of drywall,
let it sit overnight uncovered ( living in the Seattle area I can do that)
and the next morning I am ready for trimming.
Gayle Bair
Bainbridge Island, WA
http://claybair.com
Cindy Strnad on thu 29 nov 01
Dear Kate,
If you're working with very large pottery, which
is where I've seen this technique used, you can
possibly trim a piece that's been cut off the bat
without fixing it to the wheel. It's heavy enough
to stay of its own accord.
The Raku clay is very groggy. That's probably why
it doesn't crack. Can't tell you about the white
earthenware, but it's likely a difference in
composition. You can try wedging some grog into
the red and the black that have been giving you
the trouble. That does sometimes help.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com
Kate Johnson on thu 29 nov 01
Hi Cindy and list...
> If you're working with very large pottery, which
> is where I've seen this technique used, you can
> possibly trim a piece that's been cut off the bat
> without fixing it to the wheel. It's heavy enough
> to stay of its own accord.
Ah, well, I seem to mostly make bowl or mug-sized things most successfully.
The largest piece was a medium sized punchbowl...not really that heavy...
>
> The Raku clay is very groggy. That's probably why
> it doesn't crack. Can't tell you about the white
> earthenware, but it's likely a difference in
> composition.
Perhaps so, I've read that it's pretty stable, and my experience seems to
bear that out. The white earthenware, on the other hand, is not groggy at
ALL, it's very smooth and soft (feels like of flabby!). Very different
to throw, and hard for me to get used to. I prefer something with more
body...anyway, odd that those two very different clay bodies are the ones
that seem to fire most successfully in the electric kiln. They fire at the
same temp, though, and I'm wondering if that has something to do with it.
You can try wedging some grog into
> the red and the black that have been giving you
> the trouble. That does sometimes help.
They both seem to HAVE quite a bit of grog already. It's visible even when
I smooth the clay, but when I use a sponge on an edge, for instance, it
looks quite sandy--not at all like the white earthenware or the terra cottas
I've seen. They're commercial boxed clays, FWIW.
Oh, yes, another question...is white earthenware supposed to still smell
like wet clay even after it's been biscuit fired? I know since it fires at
a lower temp it doesn't vitrify quite as much as the stonewares, am I right?
I rinsed off a mug before glazing tonight and it really had a wet-clay scent
to it--doesn't seem as though it should smell like that...
Best--
Kate
| |
|
