Technical examination of Wat Sisowath Ratanaram panel painting

The technical examination on the early 20th century panel painting of Wat Sisowath Ratanaram was performed using optical microscopy (OM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), Micro-Raman spectroscopy (μ-RAMAN), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The investigation shows the mixture of minium, cinnabar and baryte in red preparation layer, quartz from the natural earth pigment in the underpaint layer and the pigments mixed with the additives in the paint layer. There are various pigments found in the paint layer ranging from emerald green, chalk, baryte, chrome yellow, ultramarine blue, carbon black and zinc white. Zinc white was widely utilized as the additive of green, yellow and blue paint layer. In addition, minium and carbon black were used to draw fine lines for image details. The degradation products of gypsum in the paint layer were evidenced by SEM-EDS and XRD. While the darkening of red lead in the red preparation layer was observed by OM. The trace of natural plant resin as a binding meium was found in S_Wood and S_Black samples evidencing by ATR-FTIR and Py-GC/MS. The 7 steps of painting technique were proposed by implementing all detailed scientific information.