Dear M. White;-
I have had excellent results cleaning the outside of shells by putting
the shell in a solution of 75% bleach. Purex, something like that. It
does not damage the shell. It DOES disolve the periostricum and the
hinges on bivalves. It loosens encrustations fairly quickly. Try 15
minutes. I have also (unintentionally) left shells in such a solution
overnight with no bad results. You must wash them off in fresh water.
And you may be sure your hands will smell like bleach for the rest of
the day.
Welcome to the list.
Art