江戸時代後期に輸入された唐棧布(とうざんふ)に使用された黄色の金属化合物染料

抄録

  The metallic compound of the yellow dyestuff used for touzan cotton fabric imported in the late Edo period has been investigated. Cotton threads dyed three colors, indigo blue, shellac dark red and unknown yellow, are used in the specimen. The color is analyzed with a spectrophotometer. The microstructures are observed by SEM. The composition and crystal structure are analyzed by EDX and XRD, respectively. The average diameter and length of the cotton thread used are 20 μm and 27 mm, respectively. From the size, the cotton is thought to be made in a country in Southeast Asia. Many particles 1-2 μm in length and 0.2-0.7 μm in width are observed on the thread surface. The absorption edges at 536 nm (2.3 eV) and 730 nm (1.7 eV) are observed in the reflectance spectrum. The yellow color is determined by the edge at 536 nm, and the dyestuff material is a semiconductor having the band gap of 2.3 eV. Chromium (Cr) and Lead (Pb) species are detected from the surface and the inside of the cotton fiber. The metallic compound, PbCrO₄, is detected by XRD; this compound is called chrome-yellow and was developed in Europe at the beginning of the 19th century.