The vast majority of old photo collections have some hand-coloured prints. The study of these images and their conservation have been the subject of two research projects supported by the MEC and UPV / EHU that have been conducted by researchers and professors of the University of the Basque Country. These projects have evaluated the effect of the most common paper conservation treatments on the selected paintings techniques (watercolours and oil paintings) and on the components of the photographic image, in salted papers, albumen and chemical developed gelatine prints. All this work has lead to a PhD thesis presented at the Department of Painting of the UPV/EHU in 2009.