Describes the re-creation of objects from their concretions, which had formed about the encrusted decomposing objects excavated by the University Museum of the University of Pennsylvania, 1961-4, from a Byzantine ship off Yasor Ada (Lodo). Each was cut in half with a lapidary saw. The concreted mold was thoroughly cleaned of its iron oxide contents. A shim of heavy paper or thin cardboard was glued to its cut surfaces to compensate for the thickness of the saw blade. The casting process experimented with different compounds: Silastic 589 RTV, a silicone rubber manufactured by Dow Corning Corporation, Englewood Cliffs, New Jersey; and Smooth-On Flexible Mold Compounds 100 and 300, polysulphide rubber compounds produced by Smooth-On Manufacturing Co. of Jersey City, New Jersey. It is recommended that the Smooth-On compounds be used in the process of iron replacement. -- AATA