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EFFECTS OF COPPER ON DEGRADATION OF JAPANESE WOOD-BLOCK PRINTING PAPER OF THE LATE EDO ERA AND MODERN JAPANESE PAPER

Abstract The effect of copper-containing pigments on the deterioration of Japanese paper is investigated. A hand-coloured wood-block print of the late Edo era is used as a naturally aged specimen and modern Japanese papers painted with powdered malachite are used as accelerated ageing specimens. Discolouration of the print is examined with a three-dimensional fluorescence spectrometer and a spectrophotometer. Copper content in the specimen papers is measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS). The copper concentrations of the cross-sections of both types of specimen show a gradient. In addition, the copper concentration at the same depth of the artificially aged specimen paper shows an increase as time at high temperature increases. This results in a diffusion of copper species from the recto to the verso of the paper.