Egyptian and Graeco-Roman wall plasters and mortars : a comparative scientific study

• Main Author: Abd El Salam, Safaa A.
• Published: University of Leicester 2001
• Subjects: 932
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.697016

The development of methods of examination and analysis for painted plaster allows us to identify and determine not only the original materials used, but also to define the causes of subsequent alteration, which has affected both the painted layers and the rendering. The aim of this research is to examine and analyse wall plasters and mortars from different sites and periods, in order to identify composition, structure and mineral content, and to define the main forms of deterioration and decay affecting the wall paintings. The strategy of examination of these materials is divided into three stages with the following analytical methods. 1-Preliminary analysis: In the initial examination a microscope was used at 10X magnification and to look at polished cross-sections, to identify the structure of the mortar and the painted layers. 2-Chemical and micro-chemical analysis: Microanalysis (spot tests). Standard methods were used to identify the quantitative and qualitative nature of the composition of plasters and mortars, including the measurement of the calcium carbonate (CaCO3) content, of the layers and in some instances the deposit which covered the painted surface, and the analysis of any water-soluble salts. The analysis of pigments was carried out using micro-chemical tests. 3-Physical methods: X-ray diffraction and X-ray powder diffraction (X-RD & X-RPD) confirmed the mineralogical compounds in the plasters and pigments. Induction coupled plasma spectroscopy (ICP) detected the other metal ions present in the materials. Polarized light microscopy (PLM) revealed internal structures. Scanning electron microscopy and dispersive X-ray microanalysis (SEM & EDS) were used for surface structure and to define deterioration and decay factors.