A preliminary investigation into the identification of adhesives on archaeological pottery

Abstract

The successful removal of a failing adhesive from archaeological pottery is facilitated by its identification. The aim of the present study was to establish an analytical path for the identification of adhesives commonly found on archaeological pottery, using resources that would be accessible to a conservation laboratory in Australia. Consultation and research of literature established adhesives that were historically used to repair archaeological pottery. Analysis of control samples assessed a spectrum of analysis techniques (visual, chemical and instrumental). It was found that simple analysis methods such as appearance, UV fluorescence and solvent solubility, are useful for identifying natural products, such as shellac and animal glue; chemical spot tests allow identification of animal glues and cellulose nitrate; and Fourier transform infra-red aids with identifying the presence of additives and with differentiating between poly(vinyl acetate) and acrylic formulations. These observations from the control samples were used to develop an analytical path for identifying adhesives associated with archaeological pottery. This path was tested on adhesive samples obtained from three artefacts in the Cypriot Collection at the University of Melbourne. Five adhesive samples were identified to be based on either cellulose nitrate, poly(vinyl acetate) or an acrylic. These identifications showed the usefulness of the analytical path developed and allowed an assessment to be made of adhesive performance. However, this exercise also raised unexpected questions.