Patrick Logue on fri 24 aug 01
hi
Thanks for responding everyone.
To address things you brought up;
Tiles are dried between two sheets of drywall over 2
to 3 wks.
Tile, design, and everything is pressed.
tiles are a uniform 3/8" with 1/8" relief.
I redesigned one piece with a more shallow relief and
it did the same thing.
The only thing I can think of now is that maybe i'm
not generating enough pressure.
I welcome any suggestions or ideas
Thanks again
Pat
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K. Sam Miller on fri 24 aug 01
Pat,
This may not be relevent to your situation, but I made a series of 4 to 5
bas relief tiles a while back. Every one of them cracked despite
significant drying time under plastic (multiple weeks). The explanation
that my instructor & I finally settled on was that I started sculpting the
tiles from a block of clay cut directly off my bag clay. I did not compress
the block before I started, thus the clay lacked the increased structural
integrity gained by this compression process. I haven't done any more tiles
since then, so haven't had a chance to test this theory.
Sam
----- Original Message -----
From: "Patrick Logue"
To:
Sent: Friday, August 24, 2001 7:40 AM
Subject: cracking tiles/ more specifics
> hi
> Thanks for responding everyone.
> To address things you brought up;
> Tiles are dried between two sheets of drywall over 2
> to 3 wks.
> Tile, design, and everything is pressed.
> tiles are a uniform 3/8" with 1/8" relief.
> I redesigned one piece with a more shallow relief and
> it did the same thing.
> The only thing I can think of now is that maybe i'm
> not generating enough pressure.
> I welcome any suggestions or ideas
> Thanks again
> Pat
>
> __________________________________________________
> Do You Yahoo!?
> Get personalized email addresses from Yahoo! Mail
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>
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>
Diane Winters on sun 26 aug 01
Hi Patrick
For us the crack's the problem, but for the piece it's the solution.
Other folks have offered some very good observations and suggestions. One
thing I learned from the Hamer/Hamer book's outstanding section on crack
analysis is to look for the widest point of the crack as that's where it
began (the epicenter [I live in earthquake country]). You don't mention
when those cracks are showing up - greenware?, bisque? Wherever the widest
point of the crack seems to be when it does show up, look right at that area
on a freshly formed tile, and see if you can see anything unusual or
different from your other tiles, like slight stretch marks for instance, or
an abrupt change in thickness. If the widest point of the crack is at the
edge of the tile, that's another matter and may more likely relate to drying
or readsorption than to forming.
Also, when you say you're pressing them, do you mean pushing clay into the
mold with your hand, or pounding it in with a mallet, or using a mechanical
manual or hydraulic press? I recall you were looking into hydraulic
presses.
By the by, I just seem to have solved (dangerous to say solved, I may regret
that) a particular tile cracking problem I'd been having lately, that I'm
sure is NOT related to what you're having, as it was completely inconsistent
as to which designs or areas of a design were affected. They appeared
following my ^05 bisque firings, involved cracks from the edge, and appears
to have been due to dunting on cooling. My clay body is a stoneware
sculpture body with quite a lot of fine grog. I used to push the cooling a
little at the tail end, I mean once it was below 250 F or so, by first
pulling just the bottom peep, waiting till I could easily hold my hand in
front of the top peep, then pulling the rest of the peeps and waiting til
the temp was down to about 120, then cracking the lid an inch and so on.
Very conservative pushing I thought, and assumed my clay body could handle
it. Well, it turns out if I let the kiln cool COMPLETELY on its own, I
don't get the cracks. As I said though, I don't think this is the same as
what's happening to you.
Hoping you can get it solved. I know it's frustrating.
Diane Winters
diane@winterstileworks.com
-----Original Message-----
From: Patrick Logue
To: CLAYART@LSV.CERAMICS.ORG
Date: Friday, August 24, 2001 8:16 AM
Subject: cracking tiles/ more specifics
>hi
>Thanks for responding everyone.
>To address things you brought up;
>Tiles are dried between two sheets of drywall over 2
>to 3 wks.
>Tile, design, and everything is pressed.
>tiles are a uniform 3/8" with 1/8" relief.
>I redesigned one piece with a more shallow relief and
>it did the same thing.
>The only thing I can think of now is that maybe i'm
>not generating enough pressure.
>I welcome any suggestions or ideas
>Thanks again
>Pat
>
>__________________________________________________
>Do You Yahoo!?
>Get personalized email addresses from Yahoo! Mail
>http://personal.mail.yahoo.com/
>
>___________________________________________________________________________
___
>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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