Cob: Scientific Ceramics

Sun May 14 11:27:51 CDT 2000

Amazing, has modern cob actually spread around the world?  That is exciting.

You people who are discussing tiles I suggest going to  your local library and
getting a book on pottery and instead of speculating get some basic information
about this ancient of technologies. 
 Adobe is sun dried clay, the same as cob..
Earthenware is very low fired clay, fragile but will not disintegrate in
water.I  saw them fire it in the street in Nicaragua with no kiln, just stuck
in a pile of leaves. In India they fire it in a great pile of dung that burns
for days. There are many primitive ways of making low fired ceramic tiles. 
They use less fuel than high fired tiles like those in your bathroom.  They
last in many kinds of weather but gradually disintegrate.  They can  be made
very colorful by using different chemical glazes, even mineral glazes.made by
just grinding rock.  Potters use a slab roller to make them. A tortilla press
would probably work if it could be adjusted to make the thicker.  They can be
made by pressing the clay into forms which allows any kind of design you carve
into your form.  One interesting idea was pressing leaves onto the surface.
The  leaves burned up in the firing but left an impression of their shape and
veins.

Stoneware is higher fired clay.  Tiles made of it are a lot more durable.  To
fire them you need a specially built kiln and fire and them and to use
different materials for glazing.  Your pottery book will tell you all about
that.

Porcelain is still higher firing. Not something most people would want for
building.  The clay is rarer, the firing higher.

I believe all the fired tiles are sufficiently impermeable to be risky for cob
wall surfaces because of the trapping of moisture under them.  It will be
interesting to learn what happens to the bathroom walls in the long run that
are tiled.  Perhaps a stabilized earth using a silicate mixed with clay, not
just as a surface coating, might make a more durable bathroom wall.  One could
mix Portland cement with the clay or a petroleum product.  The builders have a
secret mixture they use in Arizona for their adobe bricks to stabilize the
clay.  Does anyone know what it is?

Have fun with your tiles but don't burn too much fuel to make them.  Cob
builders are environmentalists and think about their impact on the
environment.  One reason cob is so great is its low environmental impact. You
don't need wind to make a kiln hot, just a lot of fuel.  Some believe the
deserts in eastern China were created by cutting the forests to fire the kilns
for China - porcelain.
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Amazing, has modern cob actually spread around the world?  That is
exciting.<br>
<br>
You people who are discussing tiles I suggest going to  your local
library and getting a book on pottery and instead of speculating get some
basic information about this ancient of technologies. <br>
 <b>Adobe</b> is sun dried clay, the same as cob..<br>
<b>Earthenware</b> is very low fired clay, fragile but will not
disintegrate in water.I  saw them fire it in the street in Nicaragua
with no kiln, just stuck in a pile of leaves. In India they fire it in a
great pile of dung that burns for days. There are many primitive ways of
making low fired ceramic tiles.  They use less fuel than high fired
tiles like those in your bathroom.  They last in many kinds of
weather but gradually disintegrate.  They can  be made very
colorful by using different chemical glazes, even mineral glazes.made by
just grinding rock.  Potters use a slab roller to make them. A
tortilla press would probably work if it could be adjusted to make the
thicker.  They can be made by pressing the clay into forms which
allows any kind of design you carve into your form.  One interesting
idea was pressing leaves onto the surface. The  leaves burned up in
the firing but left an impression of their shape and veins.<br>
<br>
<b>Stoneware </b>is higher fired clay.  Tiles made of it are a lot
more durable.  To fire them you need a specially built kiln and fire
and them and to use different materials for glazing.  Your pottery
book will tell you all about that.<br>
<br>
<b>Porcelain</b> is still higher firing. Not something most people would
want for building.  The clay is rarer, the firing higher.<br>
<br>
I believe all the fired tiles are sufficiently impermeable to be risky
for cob wall surfaces because of the trapping of moisture under
them.  It will be interesting to learn what happens to the bathroom
walls in the long run that are tiled.  Perhaps a stabilized earth
using a silicate mixed with clay, not just as a surface coating, might
make a more durable bathroom wall.  One could mix Portland cement
with the clay or a petroleum product.  The builders have a secret
mixture they use in Arizona for their adobe bricks to stabilize the
clay.  Does anyone know what it is?<br>
<br>
Have fun with your tiles but don't burn too much fuel to make them. 
Cob builders are environmentalists and think about their impact on the
environment.  One reason cob is so great is its low environmental
impact. You don't need wind to make a kiln hot, just a lot of fuel. 
Some believe the deserts in eastern China were created by cutting the
forests to fire the kilns for China - porcelain.<br>
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