For several years I have been using a composite material for the restoration of museum specimens of many kinds. It has proven useful in the repair of a wide variety of substances, including pottery, stone, oxidized metals, bone, and ivory. It may be used wherever a strong substance is needed to fill in missing parts and to make a bond with the original pieces. It is easily prepared and used, and has many advantages over the usual repair materials. The chief of these is that it is very strong, though light; and when dry, very hard, yet completely reconvertible without damage to the specimen. Moreover, it does not shrink in drying.

I refer to this composite material, for want of a better name, as plastic clay. It has two ingredients: polymerised vinyl acetate (a synthetic resin which is described in detail at the end of this article), and powdered clay or muddy sand of 200 mesh fineness.