Wet treatment of 19th century albumen photographs with Gellan gum hydrogel: A comparison to water treatment

Abstract In the conservation practice of albumen photographs, wet cleaning techniques were long used to remove pollutions, gluing components, cellulose degradation products, and to reduce highlight yellowing. However, water immersion, as well as surface cleaning, enhances the cracking of the albumen layer surface. These cleaning methods are suitable for paper artworks. Whereas the conventional water treatment may cause irreversible damage of the paper structure, the use of rigid hydrogel of Gellan gum had been proposed as an alternative technique that is less destructive to the paper structure. Two wet treatments, water and Gellan gum hydrogel, were applied to the samples of original 19th century albumen photoprints. Their effect was assessed using instrumental methods, such as Fourier transform infrared spectroscopy, laser confocal microscopy, scanning electron microscopy, atomic force microscopy, and pH measurements. The effect of wet treatments on the albumen photograph surface cracking was quantified. Despite that Gellan hydrogel is very gentle and efficient tool for the restoration of paper artworks, it is as harmful for the albumen photographs surface as the conventional water surface cleaning, and therefore may be applied on the verso of the photographs solely.