Studies on the Conservation of Verdigris on Paper

Abstract

Abstract Verdigris (copper acetate) has been frequently used in manuscripts, early printed books and on maps. Dyes and pigments from plants have been added to modify the colour. Depending on the mode of application, paper quality, size and environmental factors like light and humidity the green colour of verdigris can discolour to brown tones and chemically damage the paper carrier. Treatment options include the application of solutions to stabilize cellulose chemically and mechanical reinforcement of the brittle or broken papers with Japanese paper and adhesives. Samples of copper acetate in gum arabic on rag paper were pre-aged to induce moderate degradation of cellulose. Deacidification, antioxidant and complexing solutions were applied by airbrush or by brush. Japanese tissue papers were coated with different aqueous or non-aqueous adhesives and applied by activation with water, ethanol or heat. The effect of the coated tissue papers was visually and mechanically evaluated before and after ageing. This contribution gives an overview of the project and focuses on mechanical stabilization and the implications of results for conservation.