Background

Japanese paintings consist of pigments and dyes laid down on substrates such as Japanese paper and silk. Deterioration of substrates and the fading and discoloration of pigments occur over time. For renovation and preservation of cultural properties, it is important to understand the deterioration of paintings scientifically. In this report, qualitative analyses of five small pieces (named “Uchi-gi”, “Matsu”, “Nami”, “Kimono”, and “Hakama”) of deteriorated Japanese paintings were performed to identify the pigments remaining on the substrate.  

Crystal phases can be identified by comparing the diffraction angle and absolute intensity of the obtained diffraction pattern with the large number of patterns included in the databases (qualitative analysis). With X-ray diffraction method, it is also possible to distinguish compounds which have the same chemical formula but different crystal packing (polymorphism) thanks to different diffraction patterns.