Llewellyn Kouba on tue 7 oct 03
Reader:
I just finished two tile samples. They are stoneware approx 13x20 and
8x13 and are about 3/8 inch thick. This morning someone else walked on the
large one and it broke. Guess it is better to find out on the sample then
on the finished product. I found I need to slip and score the ends of the
wedge pieces on the slab roller because where ever the join is not strong
they can have a tendency to crack here latter in the kiln as it is a stress
point.
I wonder if it might be possible to add some of the fiber to the clay mix?
or more grog? and or probably make them a bit thicker to insure their
safety. I also did not previously level the spot out really perfect. I
really wonder about the addition of fiber? Any suggestions for outdoor
tile bisqued, then glaze fired to cone 9. Thanks.
Llewellyn Kouba
Abbey Pottery
Richard Aerni on tue 7 oct 03
On Tue, 7 Oct 2003 08:24:51 -0600, Llewellyn Kouba
wrote:
>Reader:
>I just finished two tile samples. They are stoneware approx 13x20 and
>8x13 and are about 3/8 inch thick. This morning someone else walked on the
>large one and it broke. Guess it is better to find out on the sample then
>on the finished product. I found I need to slip and score the ends of the
>wedge pieces on the slab roller because where ever the join is not strong
>they can have a tendency to crack here latter in the kiln as it is a stress
>point.
>
>I wonder if it might be possible to add some of the fiber to the clay mix?
>or more grog? and or probably make them a bit thicker to insure their
>safety. I also did not previously level the spot out really perfect. I
>really wonder about the addition of fiber? Any suggestions for outdoor
>tile bisqued, then glaze fired to cone 9. Thanks.
Llewellyn,
First off, you did not set yourself up a fair test of your product. Unless
you have adequately prepared your substrate, any tile you make will break
when enough weight is placed upon it. There is a very long and complicated
discussion of the fired properties of clays that could take place here, but
I've not the time to do it justice at the moment.
At first glance, a thickness of 3/8 of an inch for an outdoor, weight
bearing tile seems low. Check out the relative thickness of pavers, paving
stones, etc, and compare. Also keep in mind that for indoor tile setting,
a proper substrate is essential for a successful application.
Best,
Richard Aerni
Bloomfield, NY
Snail Scott on wed 8 oct 03
At 08:24 AM 10/7/03 -0600, you wrote:
>Reader:
>I just finished two tile samples. They are stoneware approx 13x20 and
>8x13 and are about 3/8 inch thick. This morning someone else walked on the
>large one and it broke...
>I wonder if it might be possible to add some of the fiber to the clay mix?
>or more grog? and or probably make them a bit thicker to insure their
>safety.
Fiber will help their green strength, but will do
nothing to improve their strength after firing.
3/8" is very thin for a 13x20" tile, though. Do
consider going thicker - a lot thicker. And
having sturdy, level support is essential.
-Snail
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