Surface changes upon high-frequency plasma treatment of heritage photographs

Recent research, concerning the application of high-frequency cold plasma in restoration and preservation of the cultural heritage, has included the objects derived from organic materials, which are highly sensitive to microclimate factors. Historical photographs made on paper base and covered with various emulsions belong to this category of heritage objects, and make the purpose of the present study. Plasma treatment was used to enhance the aesthetic aspect of the photographs by a cleaning treatment involving either physical and/or chemical etching, which did not cause major physicochemical changes on the plasma-treated surface. The photographs before and after plasma treatments were analysed by optical and atomic force microscopy, scanning electron microscopy with energy-dispersive X-ray microanalysis, Fourier transform infrared spectroscopy, colour, gloss and contact angle measurements.