Paul Herman on sat 8 feb 03
Gene Arnold,
IMHO you gotta wedge that stuff a little bit. About 50-100 shoves on the
wedging table will give you clay that doesn't make as many s-cracks.
Machines are great, and I love my peter Pugger, but some things are best
done by hand. I would not take a pug and try to throw it.
happy wedging,
Paul Herman
Great Basin Pottery
423-725 Scott Road
Doyle, California 96109 US
potter@psln.com
----------
>From: Arnolds Home Improvements
> Hello All!!
>
> I never had an s crack until I purchased a pugmill. I still compress the
> bottoms the way that I always have but still get a few of those (%&$#@!#^) s
> cracks.
>
> Someone told me to put the clay on the wheel with the end down that comes
> out of the pugmill but this hasn't stopped all the cracks.
>
> I bought the pugmill so I wouldn't have to wedge anymore, I hope this isn't
> the answer!!!
>
> Gene Arnold
> mudduck@advi.net
Arnolds Home Improvements on sat 8 feb 03
Hello All!!
I never had an s crack until I purchased a pugmill. I still compress the
bottoms the way that I always have but still get a few of those (%&$#@!#^) s
cracks.
Someone told me to put the clay on the wheel with the end down that comes
out of the pugmill but this hasn't stopped all the cracks.
I bought the pugmill so I wouldn't have to wedge anymore, I hope this isn't
the answer!!!
Gene Arnold
mudduck@advi.net
John Jensen on sat 8 feb 03
I go with the idea that the proper way to orient your pug is
sideways...like a soup can on its side. I always give my clay a bit of
a wedge before I put it on the wheel, even after it comes from the
pugmill.
John Jensen, Mudbug Pottery
mudbug@toadhouse.com , http://www.toadhouse.com
Jennifer F Boyer on sat 8 feb 03
Hi All,
A friend showed me a great way to see what the action of a pug
mill does to the clay. Take a thin slice of a pug and freeze it.
You'll see how the middle of the pug is less dense that the
perimeter. You either have to put a piece of clay on the wheel
on it's side, (the rounded edge, not the cut edge) or wedge it a
bit before throwing. If you put the cut side down on the wheel
head you have the least dense clay in the middle, forming the
inner part of the foot. Not a good thing.
Jennifer
Arnolds Home Improvements wrote:
> Hello All!!
>
> I never had an s crack until I purchased a pugmill. I still compress the
> bottoms the way that I always have but still get a few of those (%&$#@!#^) s
> cracks.
>
> Someone told me to put the clay on the wheel with the end down that comes
> out of the pugmill but this hasn't stopped all the cracks.
>
> I bought the pugmill so I wouldn't have to wedge anymore, I hope this isn't
> the answer!!!
>
> Gene Arnold
> mudduck@advi.net
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
--
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer mailto:jboyer@adelphia.net
Thistle Hill Pottery Montpelier VT USA
http://www.thistlehillpottery.com/
Never pass on an email warning without checking out these sites
for web hoaxes and junk:
http://urbanlegends.about.com/
http://snopes.com
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Vince Pitelka on sun 9 feb 03
For the last six years I did my production studio in Northern California I
used a deairing pugmill, threw the pugs straight out of the mill, and never
had S-crack problems at all. The way I designed my mill there is perhaps
more compression of the clay at the extrusion, and also the end of the shaft
comes to a gentle point, so that the clay closes around the end of the shaft
very tightly. I think a lot of deairing pugmills do not do an adequate job
of deairing, and they leave the clay a little loose around the center of the
mill, and thus the danger of S-cracks. But I don't think it has to be that
way. If your clay tends to s-crack when you use the pugs right off the
pugmill without wedging, then I would make SURE that your vacuum is right up
to specs (make sure the seals on the screen covers and the vacuum chamber
lid are all in good shape, sealing tight), and that the vacuum chamber is
kept very clean. If all that is as it should be, then you will probably
have to just wedge the clay a little as a matter of practice.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
Vince Pitelka on sun 9 feb 03
I should add to my earlier post on this subject by saying that the two
claybodies I used in production had a lot of sand or grog, and that
drastically reduced shrinkage and thus the chance of S-cracks. If I had
been using a gritless claybody I very likely would have been experiencing
S-cracks when using clay straight from the pugmill.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
John Jensen on sun 9 feb 03
Not to be argumentative; but my experience is that as few as half a
dozen turns of wedging will defeat s-cracks. I guess it all depends on
your clay and other considerations; but I was getting s-cracks in about
ten percent of my bowls for a little while because I was throwing my
from pugs without wedging. I began giving each amount 6 to 12 turns and
my problem went away. For what it's worth...this may be irrelevant: I
put my pugs on the wheel point down. I do a spiral wedge which looks
like a little cone when I'm finished and I put the point down on to the
wheel with a little bit of force.
John Jensen, Mudbug Pottery
mudbug@toadhouse.com , http://www.toadhouse.com
David Hendley on sun 9 feb 03
As John Jensen said, not to be argumentative about what works
for other people, but I regularly and routinely throw clay taken
right from my pug mill to the wheelhead. Never an S-crack.
Sometimes the "cut" end is down, sometimes it's sideways,
it doesn't matter, I never get S-cracks
I use the small de-airing Bluebird, but I suspect it has more to
do with the clay than the pugmill.
Throwing off the hump is another matter: I have to be really careful
to compress the clay, no matter how the clay was prepared.
David Hendley
Maydelle, Texas
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
> Not to be argumentative; but my experience is that as few as half a
> dozen turns of wedging will defeat s-cracks. I guess it all depends on
> your clay and other considerations; but I was getting s-cracks in about
> ten percent of my bowls for a little while because I was throwing my
> from pugs without wedging. I began giving each amount 6 to 12 turns and
> my problem went away. For what it's worth...this may be irrelevant: I
> put my pugs on the wheel point down. I do a spiral wedge which looks
> like a little cone when I'm finished and I put the point down on to the
> wheel with a little bit of force.
> John Jensen, Mudbug Pottery
Edge Barnes on mon 10 feb 03
Hello Arnold,
Rather than trying to figure which end of the pug to put down on the wheel,
throw it on it's side. This works for small weights of clay. Over 2# I end
up doing a quick wedge on the wheel head b/4 throwing it.
Edge
----- Original Message -----
From: "Arnolds Home Improvements"
To:
Sent: Saturday, February 08, 2003 5:35 PM
Subject: pugmill S cracks
> Hello All!!
>
> I never had an s crack until I purchased a pugmill. I still compress the
> bottoms the way that I always have but still get a few of those (%&$#@!#^)
s
> cracks.
>
> Someone told me to put the clay on the wheel with the end down that comes
> out of the pugmill but this hasn't stopped all the cracks.
>
> I bought the pugmill so I wouldn't have to wedge anymore, I hope this
isn't
> the answer!!!
>
> Gene Arnold
> mudduck@advi.net
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
Lee Love on mon 10 feb 03
----- Original Message -----
From: "Vince Pitelka"
> I should add to my earlier post on this subject by saying that the two
> claybodies I used in production had a lot of sand or grog,
Recently, I was looking at the analysis for the sand I use for silica and
then I looked at the silica content in Mashiko clay (Namitsuchi.) I was
surprised to see that Mashiko clay has more silica in it than the sand I have
been using. :^) When I get the time, I will try substituting Mashiko clay
for the sand in the recipes I've been developing. Probably help suspend the
glazes that are mostly feldspar.
And too, Mashiko clay doesn't get "S" cracks, even if you don't flip
your work and let it dry lip first, throwing off the hump, with a non-trimmed
bottom.
--
Lee In Mashiko Ikiru@hachiko.com
"First we must overcome the inhibitions of our Western civilization
that cause us to feel knowledge by touch is immature, primitive, and even
illegal. Among many other peoples the hand is a live instrument of experience,
used in daily life to hold, lift, grip and explore. As a tool for living, it
becomes a tool for knowing."
~~ Warren MacKenzie ~~
| |
|
