Investigation of production technique of the gold ground of korin's "red and white plum blossoms" screen, a national treasure, using portable x-ray analytical instruments

Abstract

The production technique of gold ground of a pair of folding screens by Ogata Korin, "Red and White Plum Blossoms," was investigated by using combined on-site analytical methods. In a previous study of this screen, it was pointed out that the gold ground of the screen was produced by the coating of gold paint, not an overlay of gold leaf, based on X-ray fluorescence analysis. However, there was no certain evidence of the presence of gold paint on the screen. The purpose of this study was to reveal the production technique of the gold ground of this screen by introducing new analyzing methods. We especially focused on a preferred orientation of Au crystals in the gold leaf. Since Au crystals are oriented along (100) plane in the gold leaf, X-ray powder diffractometry could be useful to distinguish between gold leaf and gold paint. We brought following three instruments: a digital microscope, a portable X-ray fluorescence spectrometer and a portable X-ray powder diffractometer to the MOA Museum of Art. They were used for nondestructive on-site analysis of the screen. Characteristic membrane-like shape was microscopically observed on the gold ground of the screen. X-ray powder diffraction patterns of the gold ground of the screen showed a strong preferred orientation parallel to the (100) plane. We also analyzed a reference picture painted with gold paint and found a striking difference between the gold paint and the gold ground of the screen. We carried out line analysis by using an X-ray fluorescence spectrometer, while focusing on a checkered pattern on the gold ground of the screen. The intensity of Au-L lines of the checkered area was a few times stronger than that of the ground part. Therefore, it was indicated that the checkered area was produced by overlapping of two gold leaves on the screen. From these observations, we have concluded that the gold ground of the screen could be produced by the gold leaf. © 2011 The Japan Society for Analytical Chemistry.