Redox Syndrome

Some processed silver gelatine microfilms in storage for two to twenty years have developed small coloured spots or blemishes. The fogged leader at the outside of the roll is most frequently affected by the blemishes, which are generally red or yellow in colour and are smaller in size than the image characters (for example, a typewritten letter reduced 20X) on the microfilm. Other common areas for redox to start are fingerprints and areas where adhesive tape is in contact with the film.

The two sample images above show the early stages were a small number of spots are present and a frame that is well advanced, with considerable image degradation.

Once the deterioration of the microfilm occurs it cannot be reversed. The blemishes result in the permanent obliteration of the affected images. Film duplication, molecular sieves, and Kodak Brown Toner can be used to stabilize the microfilm and prevent or slow degradation of as yet unaffected images.