Ivor and Olive Lewis on thu 21 feb 08
Dear Kjirsti Jordan,
You face us with an interesting proposition...."Anyone out there have =
some ideas for scientifically expressing the "deck of wet cards" "sheets =
of wet glass" "electromagnetic bonds"; "hexagonally shaped mass like a =
phone book with layers of sheets"; phenomenon of most moist clay =
particles that might intrigue students in middle to high school? (Yeah, =
we have the real thing right there in front of us but many kids don't =
get the analogies.)"
Not all of the models are tenable. For example, Lawrence and West in =
Ceramic Science for the Potter tell us that the electronic forces =
associated with a single crystal of clay surround the edges leaving the =
faces neutral. So the build up of water would be around the crystal. =
This approximates into a Toroidal shape, like a Polo Mint. Given minimal =
lubrication this form permits universal motion in three dimension. But =
it cannot be true.
My suggestion is that you read more widely into the topic of Clay/Water =
relationships.
Ralph E. Grim, "Clay Mineralogy" presents valid information not given =
elsewhere.
W. E. Brownell, "Structural Clay Products". ISBN 3-211-81382-9. This =
presents a scientific view of the nature of water.
If you believe that in plastic clay those "Hexagonal Plates" slide past =
each other lubricated by a thin film of water, how would you reconcile =
this model with the Volumetric rather than the Mass relationship of the =
two main ingredients of a plastic clay ? Assume a clay body with two =
thirds by weight Clay and one third by weight water with density of =
clay as 2.6 and of water a 1.0.
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