江戸時代木版本・鼓銅国録（こどうずろく）に使われた鉛丹の微細構造と変色

摘要

鉛化合物を原料とする顔料は古代ギリシャおよび古代中国 などで作られ，わが国には唐の時代に伝わったとされてい る．%The microstructures of red lead (minium) pigment and the behavior of the Pb species used in the wood-block-printed book Kodouzuroku published in the late Edo period have been investigated. A copper refining technique of the late Edo period is described in this book. Although the red lead pigment was used for the color of the flames in the illustration of the refining process, the color has long changed from red to black. A very small specimen is taken from the picture and then thinned by the focused-ion-beam method. The microstructures are observed using a transmission electron microscope. The Pb_3O_4 crystals exhibiting the red-color are detected in the pigment layer. The crystal diameter is 6 ～17 nm. Pb species that diffused from the pigment layer into the glue, which was used as a binding medium, are detected. The diffused Pb species are also detected in the paper fiber. Furthermore, nanosize αPbO particles have precipitated in the paper fiber. The Pb species diffused into the glue and paper fiber cause the blackening of the pigment layer and the paper fiber.