Walnut shell grit blast media

We are conducting some experiments in the construction of leaded
bronze cast bowls employing the lost wax method.  We would like to
clean the surface of the cast bowls without getting rid of any
evidence imparted from the mold material. Upon investigation, we
have found that walnut shell grit might do the trick. Could someone
please recommend an appropriate grit size for walnut shell grit
blast media?   Also, a reputable source for purchase would be
greatly appreciated.

Heather Galli
Graduate Student of Archaeological Studies
Yale University
Department of Anthropology
51 Hillhouse Ave.
New Haven, CT 06520
203-432-3772


                                  ***
                  Conservation DistList Instance 19:36
                Distributed: Wednesday, February 8, 2006
                       Message Id: cdl-19-36-017
                                  ***