This is a bit off your original topic but maybe it will benefit someone...
When I was trying to find a new supplier for air dry clay for use in our
elementary program, I spoke with an owner of an art clay company in our
state who suggested using regular low fire white clay with a coat of
Elmer's Glue. Students just rub it on after they have finished forming the
piece (wet). We have found this to be a much more inexpensive clay than the
("Air Dry") clay that we used in the past and it is having a similar success
rate. The success rate is contingent upon the design of the piece: thin
parts break off so easily in an elementary student's hands. I try to
encourage, for example, no thin legs (perhaps a sitting pose instead),
thicker ears, and tails that lay against the body. We discuss how artists
must work with the qualities (and sometimes the restrictions) of the art
medium....
Mary