Blemish Formation in Processed Microfilm II

Gaseous peroxides form blemishes on some processed microfilms. Two procedures are given for testing the blemish susceptibility of processed microfilm, one using peroxide paper and the other zinc powder as a source of peroxide. The susceptibility of microfilm to blemish formation decreased when conditioned at 86 percent relative humidity and 26 °C. Coarse-grain microfilms are less susceptible to blemish formation than fine-grain microfilm. Fine-grain microfilms fixed in ammonium thiosulfate were less susceptible to blemish formation than those fixed in sodium thiosulfate. Oven-aged microfilm storage cartons were found to generate peroxide when wetted. The microfilm base readily absorbed hydrogen peroxide.