Toward an assessment of cleaning treatments onto nineteenth–twentieth-century photographs by using a multi-analytic approach

The application of cleaning treatments for the restoration of nineteenth–twentieth-century photographs represents an innovative and still little explored aspect. In this work, in order to remove the degradation products, two cleaning methods were used for two different photographic techniques: poly(vinyl alcohol)-based hydrogels were applied to clean an albumen-based print, while calcium chlorine was used to remove the silver mirroring effect on a gelatin silver print. The constituent materials and conservation state of the analyzed photographs were characterized using a multi-analytical approach: imaging analyses (UV–VIS-NIR), attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FT-IR) spectroscopy, macro-X-ray fluorescence scanning (MA-XRF) spectroscopy, pH analyses and particle-induced X-ray emission (PIXE) were applied before and after the cleaning treatments. The two treatments have permitted of the recovery the degraded parts of the two photos, especially in the first study case. For the silver mirroring effect, further treatments will be required to obtain a complete removal of the effect.