Artificial Ageing of Japanese Lacquerware and Comparison of Conservation Treatments for Photodegraded Japanese Lacquer Surfaces

Abstract

The aim of the work was to devise a methodology to artificially age urushi (Japanese lacquer) samples and to test a series of different treatments, both Western and Japanese, to conserve urushi objects for future generations. The results of this work need to consider the wider implication of cross-cultural objects to obtain the most effective and sympathetic conservation treatment. By comparing the Mazarin chest (an urushi object at the V&A museum) and two other disparate, yet related, cross-cultural conservation and restoration projects, it is demonstrated how the cultural background of an object can affect its value and the consequent effects this can have during conservation. Microcracks form on the surface of urushi as it ages, similar to those seen from desiccation cracking. These microcracks are initiated by the formation of pinholes and light degradation. The pinholes form because of changes in relative humidity. Temperature also plays a role in the formation of pinholes, but oxidation occurs at high temperatures. Different light sources will produce different degradation of urushi surfaces. The effect of solvents used for cleaning and diluting urushi were tested. Polar solvents such as acetone damage the surface of urushi. Solvents that would be suitable for conservation include Solvesso A and Han 8070. Two conservation materials were used to treat aged urushi surfaces: a Western resin (Paraloid B72) and urushi. Both gatame (used dilute to fill the cracks) and suri (used to cover the surface) style treatments were used. The B72 was too dilute to draw any conclusions on its effectiveness. Using urushi, the suri treatment was more effective than gatame. The effect of a coating of shellac, as was often used to ‘restore’ urushi objects in the West, was also investigated. The shellac showed some cracking after ageing, and was very difficult to remove even with aggressive solvents.