ivor & olive lewis on tue 11 aug 09
Dear Ric,
Comments!
To discriminate among these three categories something must be said about
particle size and colloidal properties.
As a Teacher, what are your thoughts?
Best regards,
Ivor Lewis,
Redhill,
South Australia
Karen Sullivan on tue 11 aug 09
The discussion about clay has been interesting...
Today driving home from lunch, I saw some houses
With terra cotta round tile houses that still
Had green moss/mold...
So it is the basis of how I think of the variety
Of clays....in their characteristics...
Porosity....to vitreous ness (is that a word?)
Plasticity....to short ness
Due to particle sizes...flat platelets to cube shaped particles
in porcelain
Color...red...common...secondary clay to white...primary clay
Temp....low to high
These are a few of the considerations I
Think about when I think of clay...
So earthenware...red...plastic...porous....low fire
At one end of the spectrum...
Porcelain....vitreous...short....sort of....
White...primary...high fire...
So the moldy green tile roofs where
Terra cotta clay....porous...able to grow
And sustain mold...as they hold water...
This is August in So...Calif...I would
Think the Sun would bleach...dry the roofs...
But I guess not....
Karen
Who seems to have too much
Free time....
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