Dye analysis of Shosoin textiles using excitation-emission matrix fluorescence and ultraviolet-visible reflectance spectroscopic techniques.

The dyes of 8th century textiles, treasured for more than 1250 years in the Shosoin treasure repository in Japan, were analyzed by nondestructive methods, i.e., excitation-emission matrix (EEM) fluorescence and ultraviolet-visible (UV-vis) reflectance spectrometry, in combination with natural dye references extracted from plants, which have been widely used from ancient times. In this analysis, five dyes were found in the following objects: embroidered shoes dedicated to Great Buddha of the Todaiji temple by the empress of that time, the cloth lining for a case holding a mirror belonging to the emperor of that time, two rolls of yellow and light green plain-weave silks, and a sleeveless coat used for a musical in a Buddhist ceremony in 752 A.D. EEM fluorescence spectrometry distinguished kihada yellow (Amur cork tree), kariyasu yellow (eulalia), and akane red (Japanese madder). UV-vis spectrometry also distinguished kariyasu yellow, ai blue (knotweed), akane red, and shikon purple (murasaki); the characteristic peaks of these dyes were detected by a second derivatization. The results show that although the dyes used easily degrade with age, EEM fluorescence and UV-vis reflectance spectrometry are useful for distinguishing dyes used in the Shosoin textiles, which had been stored for more than 1250 years.