Characterization of historical gypsum mortars

The investigations, which were initiated as part of a study by the Federal German Association of the Gypsum and Plasterboard Industry, were centred on seven different historical mortar samples. The intention was to discover how far it is possible to record the special features of historical gypsum mortars and then, on the basis of the results obtained, reproduce durable mortars which are as true as possible to the original. The study revealed differences and common factors between the different mortars. The reasons for their durability can only be deduced in conjunction with their origins and by including reference samples. This will form the basis of further work on this subject.