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cracks in tiles

updated fri 4 aug 00

 

Jean Lutz on tue 1 aug 00


I've had things crack in the past and usually the cracks have been short
and straight. However, recently I made some tiles that were 1/4 inch thick
and between 5 and 6 inches square. Some survived but some cracked. The
crack in one was nearly all the way across the tile and was wavey. Any clue
as to why it was wavey??
Jean Lutz
Scottsdale, AZ

Vicki Katz on tue 1 aug 00


I have had that problem in the past & still don't know exactly what caused
it. I changed the way I make tiles now. I dry them sandwiched between
pieces of sheetrock & handle them as little as possible. That seemed to
resolve the problem. Also, I think I stressed them by bisque firing them in
a tile setter, now I just stack them in the bisque firing, one atop another.
Do you have one of those wonderful tile cutters from GEORGIA by any chance?
They are pricey, but indistructable & really do made nice tiles for small
projects. They will probably outlive me, so I splurged & have 2 now.
By the way, I have done a couple projects, but tile making is not my focus.
Makes ya sick when things like that happen though, I understand.

Paul Lewing on tue 1 aug 00


Jean,
Did you wedge the clay? That'll make them crack every time.
Paul Lewing, Seattle

NCGHandmadeTile@AOL.COM on wed 2 aug 00


Hi Jean, I had to go to the archives to see your post, somehow it missed me.
Everyone elses responses had me wondering. Anyway, I'd be interested to
know how you dried your tiles. Also, 5-6" by 1/4" is a little thin, but I've
seen it done. Were there cracks before you fired? Or did the cracks appear
after bisque? Or after glaze?

Nancy G.

Pancioli on wed 2 aug 00


Please tell us how you made and fired the tiles, temperature, schedule,
loading, etc. Then I can guess at the reason for the cracks.

Thanks.

Diana

Richard Jeffery on wed 2 aug 00


Anyway, I'd be
> >interested to
> >know how you dried your tiles. Also, 5-6" by 1/4" is a
> >little thin, but I've
> >seen it done. Were there cracks before you fired? Or did
> >the cracks appear
> >after bisque? Or after glaze?
> >
> >Nancy G.
> >

I've made clock faces that size, that thin - using paper clay, then rakuing
them, which would sort out most cracks.
Drying is in stacks, newspaper between each layer, then particle board or
kiln shelves on top and at various points to weigh down. I usually turn
them every 12 hours or so. Seems to sort out warping in the drying and the
bisque phases.

I did have a problem firing tiles in a simple raku gas kiln - warped even
during short glaze firing. That turned out to be kiln shelf getting too
hot, so redesign sorted that.

When I have a big clock face - say 8" x 10", I tend to bisque the tile flat
on something mobile like sand - I usually grind up a bit of broken soft
brick - it only takes a teaspoonful. Something that size would definitely
be the first load in the raku kiln and fire up from cold, and might get the
ball bearing treatment too. Anything small - say 6" x 4" probably gets
fired as a stack on their sides.

Hope this helps

Richard
Bournemouth UK
www.TheEleventhHour.co.uk

> >_____________________________________________________________
> >_________________
> >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.
> >

Janet Kaiser on wed 2 aug 00


Forgot to mention cutting tiles straight off a block...
Use a harp with the wire set at the thickness you want.
This eliminates the stresses in the clay created by
rolling. Bronwyn Williams-Ellis told me about this
method. She also uses it successfully on smoother
earthenware clay bodies with little grog. She then
pricks the bottom of the tiles all over with an ancient
large square (hand wrought?) nail. Works for her.

Janet Kaiser
The Chapel of Art . Capel Celfyddyd
HOME OF THE INTERNATIONAL POTTERS' PATH
Criccieth LL52 0EA, GB-Wales Tel: (01766) 523570
E-mail: postbox@the-coa.org.uk
WEBSITE: http://www.the-coa.org.uk

----- Original Message -----

> Hi Jean
>
> No matter what clay you use, I suspect a quarter inch
> thickness on tiles 5 to 6 inches big is just too
thin.
> The commercial tiles this thick are made of highly
> compressed powdered clay, not plastic clay, which is
> why they are OK. I have never seen hand made tiles
this
> thin and size work.
>
> Secondly, tiles are a tricky business, but some of
the
> tricks and tips I have picked up during the course of
> the past three years are:
>
> 1. Use well wedged, heavily grogged clay already on
the
> dry side
> 2. When rolling out the clay, rotate 90 degrees each
> time.
> 3. Dry them slowly
> 4. Turn them over often during drying
>
> Bernard Leach (I think it was) recommended cutting
> tiles into a slab, but not right through until they
> were are least leather hard.
>
> Some people dry tiles in stacks. Others on racks so
> that air is drying top and bottom equally. I know one
> person, who wraps or layers them with newspaper to
dry
> "naturally". Somebody on this list suggested using
that
> plasterboard used for buildings... The stuff with
thick
> paper on both sides and plaster in the middle.
>
> I hope this helps and that when you do go into
> production, at least one is destined for The
> International Potters' Path? But 1 cm / half an inch
> thick please! :-)
>
> Good luck!
>
> Janet Kaiser >
>
> ----- Original Message ----->
> > I've had things crack in the past and usually the
> cracks have been short
> > and straight. However, recently I made some tiles
> that were 1/4 inch thick
> > and between 5 and 6 inches square. Some survived
but
> some cracked. The
> > crack in one was nearly all the way across the tile
> and was wavey. Any clue
> > as to why it was wavey??
> > Jean Lutz
> > Scottsdale, AZ

Janet Kaiser on wed 2 aug 00


Hi Jean

No matter what clay you use, I suspect a quarter inch
thickness on tiles 5 to 6 inches big is just too thin.
The commercial tiles this thick are made of highly
compressed powdered clay, not plastic clay, which is
why they are OK. I have never seen hand made tiles this
thin and size work.

Secondly, tiles are a tricky business, but some of the
tricks and tips I have picked up during the course of
the past three years are:

1. Use well wedged, heavily grogged clay already on the
dry side
2. When rolling out the clay, rotate 90 degrees each
time.
3. Dry them slowly
4. Turn them over often during drying

Bernard Leach (I think it was) recommended cutting
tiles into a slab, but not right through until they
were are least leather hard.

Some people dry tiles in stacks. Others on racks so
that air is drying top and bottom equally. I know one
person, who wraps or layers them with newspaper to dry
"naturally". Somebody on this list suggested using that
plasterboard used for buildings... The stuff with thick
paper on both sides and plaster in the middle.

I hope this helps and that when you do go into
production, at least one is destined for The
International Potters' Path? But 1 cm / half an inch
thick please! :-)

Good luck!

Janet Kaiser - in the land where one and a half inches
of rain fell yesterday and it is blowing a gale
today... But at least the summer exhibition is up and
running... What pots!!! Slobber, slabber!

The Chapel of Art . Capel Celfyddyd
HOME OF THE INTERNATIONAL POTTERS' PATH
Criccieth LL52 0EA, GB-Wales Tel: (01766) 523570
E-mail: postbox@the-coa.org.uk
WEBSITE: http://www.the-coa.org.uk

----- Original Message -----
From: Jean Lutz
To:
Sent: 01 August 2000 16:15
Subject: cracks in tiles


> I've had things crack in the past and usually the
cracks have been short
> and straight. However, recently I made some tiles
that were 1/4 inch thick
> and between 5 and 6 inches square. Some survived but
some cracked. The
> crack in one was nearly all the way across the tile
and was wavey. Any clue
> as to why it was wavey??
> Jean Lutz
> Scottsdale, AZ

Dwiggins, Sandra (NCI) on thu 3 aug 00


Janet,
What is a harp?
Sandy

> -----Original Message-----
> From: Janet Kaiser [SMTP:janet@THE-CHAPEL-OF-ART.FREESERVE.CO.UK]
> Sent: Wednesday, August 02, 2000 7:14 AM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: cracks in tiles
>
> Forgot to mention cutting tiles straight off a block...
> Use a harp with the wire set at the thickness you want.
> This eliminates the stresses in the clay created by
> rolling. Bronwyn Williams-Ellis told me about this
> method. She also uses it successfully on smoother
> earthenware clay bodies with little grog. She then
> pricks the bottom of the tiles all over with an ancient
> large square (hand wrought?) nail. Works for her.
>
> Janet Kaiser
> The Chapel of Art . Capel Celfyddyd
> HOME OF THE INTERNATIONAL POTTERS' PATH
> Criccieth LL52 0EA, GB-Wales Tel: (01766) 523570
> E-mail: postbox@the-coa.org.uk
> WEBSITE: http://www.the-coa.org.uk
>
> ----- Original Message -----
>
> > Hi Jean
> >
> > No matter what clay you use, I suspect a quarter inch
> > thickness on tiles 5 to 6 inches big is just too
> thin.
> > The commercial tiles this thick are made of highly
> > compressed powdered clay, not plastic clay, which is
> > why they are OK. I have never seen hand made tiles
> this
> > thin and size work.
> >
> > Secondly, tiles are a tricky business, but some of
> the
> > tricks and tips I have picked up during the course of
> > the past three years are:
> >
> > 1. Use well wedged, heavily grogged clay already on
> the
> > dry side
> > 2. When rolling out the clay, rotate 90 degrees each
> > time.
> > 3. Dry them slowly
> > 4. Turn them over often during drying
> >
> > Bernard Leach (I think it was) recommended cutting
> > tiles into a slab, but not right through until they
> > were are least leather hard.
> >
> > Some people dry tiles in stacks. Others on racks so
> > that air is drying top and bottom equally. I know one
> > person, who wraps or layers them with newspaper to
> dry
> > "naturally". Somebody on this list suggested using
> that
> > plasterboard used for buildings... The stuff with
> thick
> > paper on both sides and plaster in the middle.
> >
> > I hope this helps and that when you do go into
> > production, at least one is destined for The
> > International Potters' Path? But 1 cm / half an inch
> > thick please! :-)
> >
> > Good luck!
> >
> > Janet Kaiser >
> >
> > ----- Original Message ----->
> > > I've had things crack in the past and usually the
> > cracks have been short
> > > and straight. However, recently I made some tiles
> > that were 1/4 inch thick
> > > and between 5 and 6 inches square. Some survived
> but
> > some cracked. The
> > > crack in one was nearly all the way across the tile
> > and was wavey. Any clue
> > > as to why it was wavey??
> > > Jean Lutz
> > > Scottsdale, AZ
>
> __________________________________________________________________________
> ____
> 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.

Jean Lutz on thu 3 aug 00


Several tiles were made at the same time, same clay, same weather etc.
They had a little carving on them. The were all dried together between dry
wall. They were turned and the drywall changed several times during the
week they dried. They were bisqued at 06. All looked fine. No warping at
this point.
The were then glazed some all over some only in the carving. Then fired to
cone 6. The total firing took 8 1/2 hours.
Only one cracked with the wavey crack. No cracks were evident after the
bisque firing.
If you need more info just holler.
Jean Lutz

Wed, 2 Aug 2000 12:02:40 -0400
>From: Pancioli
>Subject: Cracks in tiles
>>Please tell us how you made and fired the tiles, temperature, schedule,
>loading, etc. Then I can guess at the reason for the cracks.
>>Thanks.>Diana
>