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## how to calculate clay shrinkage for tile works

### Llewellyn Kouba on thu 14 sep 00

I have a large handmade tile commission and have never worked with
calculating shrinkage. I have the book- HANDMADE TILES by Frank Giorgini
and on page 30 there is a formula. If you know two of the variable the
shrinkage can always be found. The problem is I do not understand metric
which is supposed to make it much easier? Can someone translate this
formula and how it works into something that might work on my 12 inch ruler
I would be grateful?

Llewellyn Kouba
ABBEY POTTERY
http://www.assumptionabbey.com/Pottery

### Jim Bozeman on sat 16 sep 00

Llewellen, When I was in art school here's the way we were taught to measure
the clay's shrinkage rate. Roll out a flat slab, or tile in your case, when
leather hard, make an insized line exactly 100 millimeter's long. When at
the bisqued state measure the line again; this gives you the shrinkage at
bisqued temp. Measure again after the high fire. If you end up with a line
90 mm's long then your shrinkage rate is 10%. If your ending number is
87mm's then your shrinkage rate is 13%, etc.... Makes sense to me. Jim
Bozeman
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