Ancient restorations at Hierapolis: a research on the artificial binders

A preliminary investigation on the artificial materials used in ancient restoration is presented. The knowledge on the physical properties of the ancient binders and their components is limited, due to the difficulty of obtaining good samples from blocks that have remained exposed to atmospheric agents. Some samples, belonging to monuments of the Sanctuary of Apollo, Theatre and Ploutonion, were studied and analyzed. Several analytical methodologies were applied to identify the organic and inorganic components. The mortars of Hierapolis showed the presence of animal glue and a Pinacae resin, in agreement with the recipes described in the historical sources.