THE DEVELOPMENT AND EVALUATION OF A SENSORY SYSTEM TO DETECT DEGRADATION IN CELLULOSE TRIACETATE PHOTOGRAPHIC FILM .2. SELECTION OF A SOLIDSUPPORT FOR THE INDICATOR AND FIELD TRIALS ON INDICATOR PERFORMANCE

This study is an extension of previous work where acetic acid emanatin g from degrading photographic films was detected by filter paper impre gnated with cresol red indicator. The test was destructive, requiring the removal of a small disk (hole-punch) of film. Here cresol red has been adsorbed onto a polymeric (acrylic-ester) resin to give a non-inv asive indicator which could be placed in film cans. The performance of the indicator has been assessed by testing 54 films (housed by the No rth West Film Archive al the Manchester Metropolitan University) of va rious conditions when stored at ambient temperature and humidity. The films were tested periodically over a period of 12 months. The trials indicate that the indicator successfully responds to acetic acid withi n the film storage environment, and that it can be used to alert archi vists by identifying the point prior to which films exhibit marked phy sical and chemical property changes.