slumping over real shells?

Depends.  Shells are calcium.  Calcium slowly burns off in the kiln.  Thus shells are not permanent moulds.  The calcium has a tendency to stick to the glass, so needs batt washing.

My view - it is better to make a flexible negative mould, from which a positive can be made.  This can be permanent or one use (you do have a master now)

Stephen Richard

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