Bracteates are very thin silver coins, struck only on one side, used in Germany between 1130 and 1330 AD. A major collection of these is in Gotha, where a coin treasure was found in 1900. Many of the coins were broken and badly corroded. The corrosion products were analyzed. In order to prevent further corrosion and breakage, a two-layer embedding system was developed, using dental wax and a glass cover. Dental wax was considered better than polyester or paraffin in terms of durability and reversibility. Diagrams, photographs, references.