Joy Holdread on sun 30 aug 98
>Dear Joy,
>
> I can understand your frustration with warping tiles!
> Tiles manufactured in factories are made from compressing virtually dry
> powdered clay under several tonnes of pressure thus there is no warping as
> the
> tiles are already dry enough to be fired straight away.
>
> Your tile warping problem can be aleiviated in a number of ways.
>
> a) Use a harp to cut the tiles. Rolling out the clay will create stresses
> within the clay matrix which will become apparent as the clay dries.
>
> b) Dry the tiles slowly between sheets of plaster board ( no more than 4
> layers ). The weight of the layers will help to keep them flat.
>
> c) Adding grog or molochite can help.
>
> Hope this helps - check out my site http://www.cybase.co.uk/charnock
>
> Regards
>
> Stephen Charnock
> Stephen,
> Thanks for the info. I'm not the original person writing about warping I
> responded to someone else but your #1 Use a harp intrigues me. A What??
> I'll check out your web site Sunday am as a treat. So far my geek has
> developed a web page for my dog as practice but not for me yet.
> Joy in Tucson
I'm sending this via clayart. My response to Stephen came back Return mail
host unknown. I think his solutions are of general interest. Joy in Tucson
Brian Crocker on mon 31 aug 98
------------------
Industrial tiles are made from what is known as dry powder clay which =
includes
4=25 heating oil and is pressed in a tile pressing machine.
Brian Crocker.
4 Erica Street, Tea Tree Gully, S.A. 5091
AUSTRALIA.
=7B e.mail address =7D crocker=40picknowl.com.au
----------
=3E ----------------------------Original message----------------------------
=3E =3EDear Joy,
=3E =3E
=3E =3E I can understand your frustration with warping tiles=21
=3E =3E Tiles manufactured in factories are made from compressing =
virtually dry
=3E =3E powdered clay under several tonnes of pressure thus there is no =
warping as
=3E =3E the
=3E =3E tiles are already dry enough to be fired straight away.
=3E =3E
=3E =3E Your tile warping problem can be aleiviated in a number of ways.
=3E =3E
=3E =3E a) Use a harp to cut the tiles. Rolling out the clay will create =
stresses
=3E =3E within the clay matrix which will become apparent as the clay =
dries.
=3E =3E
=3E =3E b) Dry the tiles slowly between sheets of plaster board ( no more=
than 4
=3E =3E layers ). The weight of the layers will help to keep them flat.
=3E =3E
=3E =3E c) Adding grog or molochite can help.
=3E =3E
=3E =3E Hope this helps - check out my site =
http://www.cybase.co.uk/charnock
=3E =3E
=3E =3E Regards
=3E =3E
=3E =3E Stephen Charnock
=3E
=3E =3E Stephen,
=3E =3E Thanks for the info. I'm not the original person writing about =
warping I
=3E =3E responded to someone else but your =231 Use a harp intrigues me. A=
What??
=3E =3E I'll check out your web site Sunday am as a treat. So far my geek =
has
=3E =3E developed a web page for my dog as practice but not for me yet.
=3E =3E Joy in Tucson
=3E
=3E I'm sending this via clayart. My response to Stephen came back Return =
mail
=3E host unknown. I think his solutions are of general interest. Joy in =
Tucson
Cameron Harman on fri 4 sep 98
HI,
I was sorry to see so many misconceptions about warping of
commercial tile. Let me add just a quick review.
There are three types of commercial tile used today. Firstly there
is split tile which is extruded with about 17% water. It can and
does warp if not dried properly. Second there is red clay tile
that is dry pressed and there is (third) white tile that is dry
pressed.
Dry pressing means about 4 to 6% water in the tile. It must be
prepared carefully so tat the material will flow well into the
press. Both of the pressed tile can and do warp due to a large a
variety of problems including improper die fill and improper
drying.
The white tile used in the US and UK is a mixture very similar to
the white ceramic found in hobby studios. If not dried properly it
can warp! It can be dried quickly, but must be dried right. You
folks will have exactly the same problem with pressed tile. It
must be dried in a controlled atmosphere and must be open all
around.
The idea that 4% oil is mixed in with the clay powders before
pressing is a nutty idea that people have tried from time to time.
It is by no means a standard method of pressing tile. Who would
want to add all that organic matter to burn out? The idea was that
it would save fuel, but is really quite inefficient and causes no
end of problems.
Tiles made from damp clay, for example where the clay is rolled
out and cut to size by the cookie cutter method is a viable
manufacturing method. It requires great care with drying, but can
produce a fine product.
Do not dry your tiles by placing them between flat sheets of
plaster board. You may be lucky and get it to work. I know, lots
of you will write and say "I've been doing it this way for years
with no problem". That merely means you have been lucky. It fights
nature and can cause built in stresses. You can have a tile that
looks flat after drying and then find that it cracks in drying
when those stresses relieve themselves.
A wet tile can be dried flat very quickly in a controlled
atmosphere. If you have ever been in a situation where you felt
that you had to change the body in order to make the tile without
warping or cracking, I submit that it was simply a drying
problem. Generally speaking, if you can form the ceramic in the
first place you can fire it without warping or cracking. You
cannot ignore drying, however, as it is as important as firing for
the final development of a good ceramic.
Please understand that I mean no disrespect to any of those of you
who have been taught and have yourselves taught drying methods
other than controlled atmosphere. You are not alone. A lot of
industrial people have drying problems as well because they do not
understand this important point The science of drying is not hard,
but it is complicated and somewhat time consuming, so many of the
industrial folks think that they can ignore it since it is too
much trouble.
--
**********************************************************
Cameron G. Harman, Jr. 215-245-4040 fax 215-638-1812
e-mail kilns@kilnman.com
Ceramic Services, Inc 1060 Park Ave. Bensalem, PA 19020
get your free ezine: http://www.kilnman.com/ezine/ezine.html
THE place for total kiln and drier support
**********************************************************
Susan Schultz on sat 5 sep 98
I was glad to read your opinions on tile drying, as they reflect my
experiences, but not what I read. I have had little luck with the drywall
drying technique, and wondered if I was just doing something wrong, as
it is mentioned in books and on this list as being the best way to dry tile.
I rarely make flat tile anymore, but have also changed clay bodies in
the past, as you also mentioned, thinking that I could stop warping of
flat tile. My large mural sections dry flat and crack-free (most of the time)
if they are dried very slowly.
Susan Schultz
Stonington, Ct.
Scsclay@AOL.com
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