Dear Dan,

I also learned to make epoxy casts of small objects using the silicone
rubber technique that Geoff Carver describes, in a conservation class that I
took at Texas A&M University with Dr. Donny Hamilton.  I agree that this
technique works very well for small artifacts such as lithics and can
reproduce a surprising amount of detail.  We painted the finished casts; but
as Mr. Carver describes there is also a method you can use to color the
epoxy to recreate the effect of translucent stone, but it requires
considerable trial and error.  The great thing about this technique is that
once you have the rubber mold, you can produce as many casts as you like.
It is important to “key” the two sides of the mold to each other so that
they will fit correctly back together.  Tuna fish cans with both ends cut
off work well for holding the plaster of Paris when casting small pieces.

Here are some product recommendations from Dr. Hamilton’s website (yes, it
does unfortunately include Dow products, but you may be able to find
substitutes):

“A number of different casting materials from many different manufacturers
can be used. Products that are particularly recommended include Dow silver
chloride (AgCl) silicone rubber, Smooth-On polysulfide rubber, Surgident
Neo-Plex Rubber, Permamold Latex, Hysol Epoxy, plaster of Paris, and Coecal
plaster. Many similar products could be substituted for those recommended here.”

Source: http://nautarch.tamu.edu/class/anth605/File16.htm

(Note that the casting techniques that are described on the above link are
those suitable for casting hollow marine concretions, not for casting the
type of intact objects that you are dealing with, but you may find it
interesting regardless.)

Dr. Hamilton’s bibliography provides the following references regarding
casting techniques (I’m sure there are others).  The article from American
Antiquity should be easy to track down:

Frazier, F. 1974. "Production of Artifact Casts Using Epoxy Resin." The
American Archeologist 1:33-42.

Rigby, J. K., and D. L. Clark. 1965. "Casting and Molding." In Handbook of
Paleontological Techniques, edited by B. Kummel and D. Raup, pp. 390-413. W.
H. Freeman, San Francisco.

Rohner, J. R.  1964. "Techniques for Molding and Casting with Acrylics."
Western Museum Quarterly 3(1):1-6.

Rohner, J. R.  1970. "Technique of Making Plastic Casts of Artifacts from
Permanent Molds." American Antiquity 35(2):223-226.

I hope this is helpful to you.

Best regards,
Erika Laanela
Graduate Student, College of William and Mary
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