Characterization of Organic Binding Medium in Historical Wall Paintings of Sukias House in Isfahan by Fourier Transform Infrared Spectroscopy and Chemometrics

Sukias house is located in Tabriziha neighborhood, Isfahan, Iran. Investigators have revealed that this historical house has been built during Shah Abbas II (r. 1632-1666). One of the most important decorations of this building is its historical wall paintings. The paint layer of wall painting is generally composed of pigments, organic binding media and other additives. Characterization of the binding media is a challenging problem in cultural heritage due to the presence of complex materials structure of wall paintings. The principal aim of this work is to overcome the spectral interferences for interpretation of FTIR spectra obtained from wall paintings samples. A set of calibration samples were prepared in a similar way to the strata of a real wall painting from lowest to highest complexity. Sampling from the Sukias house was accomplished as well. Each sample was analyzed by FTIR spectroscopy and spectral data set was processed by chemometrics approaches. Binding medium of Sukias house was identified as egg yolk. Results are promising in the sense that SIMCA could be useful to mine the complex FTIR spectra and characterize binding media in wall paintings which is very time-consuming and challenging by regular methods of analysis.