Salted paper prints - Preservation
Almost, if not all vintage salt prints show some signs of fading, as well as staining. Often there is an overall image fading, accompanied by some spots or areas of more noticeable fading. Many print also show areas of yellowing in the highlights (possibly due to the presence of albumen.)
Prints that were mass-produced – such as those in Talbot's 'Pencil of Nature' often show these effects more strongly than amateur prints. Probably large-scale production led to more over-use of fixing baths and incomplete washing, especially when batches of prints were washed together.
The restoration methods that have proved successful with emulsion-based prints are not suitable for salted paper prints, and when tried have been ruinous. The prints are best left alone and stored under suitable conditions to slow deterioration.
Many older prints were mounted on unsuitable boards with an interior with a high lignin content, and it may be possible to remove these.