My dentists and their staff have told me it's not the enamel they're concerned about with hard brushes, but the gums, which recede. One dentist pointed out that "they" (the American Dental Assoc.?) had urged the toothbrush manufacturers to stop stocking hard toothbrushes, with the result that it's very difficult to find "hard" brushes anymore.

So it's not the glazed surfaces of the ceramics but the softer matrix and overglaze painted designs that should concern us in our diligent scrubbing.

Gwyn Alcock
SRI, Redlands

"Archaeological & Historical Consultants, Inc." <[log in to unmask]> wrote:

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Hard toothbrushes are not supposed to be good for tooth enamel, which is pretty hard stuff. So they are probably not good for ceramics either.

Meli Diamanti
Archaeological and Historical Consultants, Inc.