A great number of mural paintings remain at the Dunhuang Mogao Grottoes. However, those that can be observed today with the naked eye have deteriorated significantly due to the passage of time. Compared with their condition at the time of their creation more than one thousand years ago, these paintings have changed greatly – colors have changed or faded and pigments have become detached and lost. Conservation of these paintings involves the elucidation of the mechanism of their deterioration and the treatment of the paintings to prevent further deterioration. Determining the original methods and materials as well as the factors that led to their present condition is essential in considering the method of their conservation. At the same time, it is also quite important in reviving the value of the paintings. Only when both are fulfilled can it be said that cultural property is truly protected. In the Japan-China joint research project, comprehensive study of these paintings is conducted. This includes observation by normal light, raking light, infrared ray and ultraviolet fluorescence photography; detailed non-destructive analysis using digital microscope, portable x-ray fluorescence and Raman spectroscope; detailed analysis of the techniques and materials as well as the condition of deterioration by micro-sampling; and detailed observation of the condition of deterioration by conservation specialists. Through such a study, the use of a great amount of organic coloring materials and the special condition of the deterioration of the mural paintings of Cave 285 (first half of the 6th century), which were not known until now, are beginning to be clarified. Moreover, radioactive carbon (14C) dating of the stone chamber and provenance study of the lead-based pigment by lead isotope ratio analysis are conducted in an attempt to do research with a large area of the Silk Road in view.
Analysis using portable x-ray fluorescence