Wanda Holmes on thu 27 jun 02
I have taken all the great advice from all of you to my posts of a few weeks
ago and now have completed a 2nd round of controlled tests. The thing that
shows the greatest interest is the position of the individual tile within
the slab - that seems to have more impact than body, cutting method, drying
method, and firing method. I plan to do more tests to confirm my results
with a larger sample, but I'd love the perspective of this group on what I'm
seeing. Specifically: I cut nine 3x3 tiles from each slab, 4 slabs per pug
of clay. Eight total slabs were included in this particular test. Working
from top left to bottom right, the positions are 1 through 9 with position 5
being the one in the middle. I generally mark the guidelines for cutting
the tiles with an "L" placed about 1/2" in from the edge of the slab. So,
the left side and top generally have the smallest margin. The margin on the
right and bottom varies but can be as much as a couple of inches depending
on the regularity (square-ness, if that's a word) of the slab. None of the
tiles were warped in drying. After bisqueing, I have 22% warping at
position 5, 29% at position 6, and from 61-88% at all other positions. Is
it possible that the edges of the slab are more prone to warping? If so,
how much margin do you generally leave?
Thanks in advance for your comments,
Wanda
Diane Winters on fri 28 jun 02
Wanda wrote:
>Specifically: I cut nine 3x3 tiles from each slab, 4 slabs per pug
>of clay. Eight total slabs were included in this particular test. Working
>from top left to bottom right, the positions are 1 through 9 with position
5
>being the one in the middle. I generally mark the guidelines for cutting
>the tiles with an "L" placed about 1/2" in from the edge of the slab. So,
>the left side and top generally have the smallest margin. The margin on
the
>right and bottom varies but can be as much as a couple of inches depending
>on the regularity (square-ness, if that's a word) of the slab. None of the
>tiles were warped in drying. After bisqueing, I have 22% warping at
>position 5, 29% at position 6, and from 61-88% at all other positions. Is
>it possible that the edges of the slab are more prone to warping>
Your controlled testing sounds so much like my own, and I'm still doing this
sort of thing off and on after 8 years in business as a tile maker.
Countless of my tiles are out in the world now bearing cryptic little marks
indicating such things I've focussed on as which edge went through the
roller first, how many passes through the rollers, whether the tiles dried
face down, or were flipped over or rotated every day, etc.
If I'm envisioning your numbering system correctly, it's number 3, 6 and 9
that passed through the roller(s) first and numbers 1, 4, and 7 that got
rolled last. I have a Bailey DVD, and have also used a Brent. With both,
the pushing/stretching/spreading effect on the slab is of course mostly
lengthwise (and increases along the length of the slab, i.e., the last end
through gets more stretch that the first). But the there's also lateral
spreading. So, if I've understood your numbering system, your best results
(positions 5 & 6) are the ones that got the least stretching/spreading
effect from the roller relative to the amount of direct compression
downward. That seems to make some sense. However, 22% - 29% warping after
bisque is still too much.
What's the solution? I've kept wanting to find "the secret," the one
elusive thing causing the problem, but have finally had to accept that if
warping were mainly due to any one thing, I'd have figured it out and
stopped it long ago. You obviously can't just roll a nine-tile-sized slab
an then scrap all but two tiles. Some of the things I do in the slab
rolling phase, in the [perhaps only superstitious] belief that I'm improving
my flatness odds are:
> roll the slab reasonlably slowly and evenly
> do it in several, or at the very least two, incrementally thinner
passes, with the semifinal pass nearly as thin as the final one, peeling the
canvas free and flipping the slab, canvasses and all, between passes
> after the final pass, I go over it once or twice with a rolling pin
sideways across the slab.
> I go ahead and cut the tiles right after rolling, but let them rest a
while after cutting before moving them to my drying boards
> and lastly, I put more of my efforts into controlled, even drying, which
I think really does have more influence than the rolling. (am also now
bisquing differently - stacks of horizontal tiles, 4 tiles high, each tile
separated by bits of moist clay)
I wish I could be more help. I know how frustrating it is.
Diane Winters
in Oakland/Berkeley by the Bay, where this afternoon a young delinquent
mocking bird had nothing better to do than come down our chimney and lodge
himself in the flue of the woodburing stove. Took us both more than an hour
to figure out how to find him a way out of the stove and then out of the
living room.
Earl Brunner on fri 28 jun 02
Are you leaving them in position until they finish drying?
Wanda Holmes wrote:
> None of the
> tiles were warped in drying. After bisqueing, I have 22% warping at
> position 5, 29% at position 6, and from 61-88% at all other positions. Is
> it possible that the edges of the slab are more prone to warping? If so,
> how much margin do you generally leave?
> Thanks in advance for your comments,
> Wanda
>
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Ilene Mahler on sat 29 jun 02
This lady is an expert,listen to what she says..She and Rikki Gill took time
out of their day to take me on a pottery tour in Berkley.Very knowledgeable
and wonderful work wanted to buy all of it..Ilene Home in Conn.. still
suffering from the time change but basically wanting to be back there the
tiles are beautiful
----- Original Message -----
From: Diane Winters
To:
Sent: Friday, June 28, 2002 8:17 AM
Subject: Re: Continuing saga of warped tiles - new results
> Wanda wrote:
> >Specifically: I cut nine 3x3 tiles from each slab, 4 slabs per pug
> >of clay. Eight total slabs were included in this particular test.
Working
> >from top left to bottom right, the positions are 1 through 9 with
position
> 5
> >being the one in the middle. I generally mark the guidelines for cutting
> >the tiles with an "L" placed about 1/2" in from the edge of the slab.
So,
> >the left side and top generally have the smallest margin. The margin on
> the
> >right and bottom varies but can be as much as a couple of inches
depending
> >on the regularity (square-ness, if that's a word) of the slab. None of
the
> >tiles were warped in drying. After bisqueing, I have 22% warping at
> >position 5, 29% at position 6, and from 61-88% at all other positions.
Is
> >it possible that the edges of the slab are more prone to warping>
>
>
> Your controlled testing sounds so much like my own, and I'm still doing
this
> sort of thing off and on after 8 years in business as a tile maker.
> Countless of my tiles are out in the world now bearing cryptic little
marks
> indicating such things I've focussed on as which edge went through the
> roller first, how many passes through the rollers, whether the tiles dried
> face down, or were flipped over or rotated every day, etc.
>
> If I'm envisioning your numbering system correctly, it's number 3, 6 and 9
> that passed through the roller(s) first and numbers 1, 4, and 7 that got
> rolled last. I have a Bailey DVD, and have also used a Brent. With both,
> the pushing/stretching/spreading effect on the slab is of course mostly
> lengthwise (and increases along the length of the slab, i.e., the last end
> through gets more stretch that the first). But the there's also lateral
> spreading. So, if I've understood your numbering system, your best
results
> (positions 5 & 6) are the ones that got the least stretching/spreading
> effect from the roller relative to the amount of direct compression
> downward. That seems to make some sense. However, 22% - 29% warping
after
> bisque is still too much.
>
> What's the solution? I've kept wanting to find "the secret," the one
> elusive thing causing the problem, but have finally had to accept that if
> warping were mainly due to any one thing, I'd have figured it out and
> stopped it long ago. You obviously can't just roll a nine-tile-sized slab
> an then scrap all but two tiles. Some of the things I do in the slab
> rolling phase, in the [perhaps only superstitious] belief that I'm
improving
> my flatness odds are:
> > roll the slab reasonlably slowly and evenly
> > do it in several, or at the very least two, incrementally thinner
> passes, with the semifinal pass nearly as thin as the final one, peeling
the
> canvas free and flipping the slab, canvasses and all, between passes
> > after the final pass, I go over it once or twice with a rolling pin
> sideways across the slab.
> > I go ahead and cut the tiles right after rolling, but let them rest a
> while after cutting before moving them to my drying boards
> > and lastly, I put more of my efforts into controlled, even drying,
which
> I think really does have more influence than the rolling. (am also now
> bisquing differently - stacks of horizontal tiles, 4 tiles high, each tile
> separated by bits of moist clay)
>
> I wish I could be more help. I know how frustrating it is.
>
> Diane Winters
> in Oakland/Berkeley by the Bay, where this afternoon a young delinquent
> mocking bird had nothing better to do than come down our chimney and lodge
> himself in the flue of the woodburing stove. Took us both more than an
hour
> to figure out how to find him a way out of the stove and then out of the
> living room.
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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>
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melpots@pclink.com.
Wanda Holmes on mon 1 jul 02
I am, though as they reach the final drying stage they do get rearranged a
bit as the outer ones dry and I consolidate boards. NOW, typing that
sentence just gave me a new idea - is it the center position in the slab
that's significant or the center position in the drying stack?????
Wanda
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Earl Brunner
Sent: Friday, June 28, 2002 9:27 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Continuing saga of warped tiles - new results
Are you leaving them in position until they finish drying?
Wanda Holmes wrote:
> None of the
> tiles were warped in drying. After bisqueing, I have 22% warping at
> position 5, 29% at position 6, and from 61-88% at all other positions. Is
> it possible that the edges of the slab are more prone to warping? If so,
> how much margin do you generally leave?
> Thanks in advance for your comments,
> Wanda
>
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.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.
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