江戸時代後期および明治時代に用いられた真ちゅう箔の腐食と和紙への影響

Abstract

The effects of metallic elements on the degradation of Japanese paper have been investigated. A hand-coloured wooden engraving print from the late Edo era and a Japanese paper decorated with metal foils from the Meiji era are used as naturally aged specimens. Metal tarnishing and paper degradation are observed in both specimens. The metal powder is observed with an optical microscope and SEM. Elements contained in the specimen are measured by means of EDX. Degradation of the paper is examined with a three-dimensional fluorescence spectrometer (TDFS). The metal foils examined with XRD. (1) On the wooden engraving print, the concentration of metal powder is Cu-28 mass%Zn. The results of TDFS and EDX show that the Cu species diffuse from the right to the wrong side of the paper. (2) On the decorated Japanese paper, the metal foil concentration is Cu-16 mass%Zn. Spheroidal grains and plate grains are observed in the tarnished parts of the foil. Cu, Zn, S and Cl are detected in these parts. The compounds Cu2O, CuSO4·2Cu(OH)2 and CuCl are detected by XRD. However, only Cu species diffuses into the cellulose. Therefore, it is thought that the degradation of Japanese paper is due to diffused Cu species.