Francis,
The macrobiotic expert on natural crocks doen't use Cybermacro Forums so you will need to visit his discussion site:
haroldkulungian
(
http://groups.yahoo.com/group/haroldkulungian/ ) and ask him there.
Is there a particular reason why you choose a crock pot over using a regular pot on, for instance, a gas flame?
Depending on your finances, cooking environment, and such there are a variety of ways that you can cook your food if for some reason you don't have a regular gas stove.
I didn't have access to a gas stove for more than 10 years and I finally started using propane during the warm months and a butane portable stove during the cold ones, until I moved and now my highest priority is access to a gas stove when looking for a new place to live.
Good luck on finding that appropriate crock-pot.
Thank you, very much.
Bruce Paine