Spectroscopic and chromatographic investigation of the wall painted surfaces of an 18th century Indian temple, New Delhi

Understanding and building knowledge about color pigments, their history and development have always been a matter of great interest through scientific exploration in the complex system of identification. The characterization of historical works of art is complicated due to the association of several other elements that influence the recorded observations. This entails investigations with multi-analytical techniques to identify the archaeological pigments and confirm their characteristics. The spectroscopic techniques especially Raman spectroscopy and Infrared spectroscopy are very useful for the identification of such materials. In the present communication, the pigments of an historical 18th century wall painting were investigated with micro-Raman spectroscopy, FTIR-ATR & FTIR-KBr, and scanning electron microscopy coupled with energy dispersive x-ray micro-analysis (SEM-EDX). The temple is an exquisite Hindu architecture with valuable artworks still surviving in New Delhi. The results demonstrated the use of red ochre contaminated with carbon for red, yellow ochre for yellow, green ochre for green color and gypsum for the white color in decorations. Lapis lazuli was identified as a pigment for blue probably sourced from Afghanistan through trade on the silk route. The stratigraphy of layers showed the use of lime as a priming layer. FTIR spectroscopy revealed the minor transformation of proteinaceous binding material into calcium oxalate in the paint layer. GC-MS results indicated the possible use of beeswax as a binder for pigments which was further support by FTIR analysis. The analytical data also reveals the trade and resources available in that period.