This article describes results of collaboration among members of the Central Institute for Inorganic Chemistry of the Academy of Sciences of the GDR in Berlin with the Institute for Monument Conservation and craftsmen in the arts, in particular on the stabilization of the came with a reversible wax mixture, application of a silicone adhesive medium, and the restoration of the transparency by means of a reduction of the manganese (IV) compounds with hydrazine hydrate. Direct lamination with organic lacquer is inappropriate; on the other hand isothermic glazing has won international approval.