The effects of temperature and humidity on the sensitometric characteristics of the photographic emulsion (Eastman Kodak SO-1213 and Plus-X Aerecon aerial film)

Abstract

The high speed of present day and future reconnaissance vehicles brings to the fore the problem of the effect of heat on the components of the reconnaissance system. This thesis presents an investigation of the effect of heat upon the photographic emulsion, considered by some the weakest link in the reconnaissance system in this regard. In addition, the effect of humidity on the photographic emulsion is studied. In order to provide a suitable system for carrying out the experimental work, a thermosensitometric test unit was designed and built. This test unit, coupled with a controlled heat electric oven, made it possible to heat emulsions for any duration of time at elevated temperatures and expose them at specified time intervals on the Eastman IB Sensitometer. The combination of this test unit and the Eastman IB Sensitometer made it possible to make careful determinations of sensitometric properties, in particular, gamma and speed. Two emulsions, Plus-X Aerecon and Eastman SO-1213, were tested at temperatures up to 240° F. at very low humidity levels. Solutions of sulfuric acid were used for humidity control with temperatures up to 150° F. The results of this experiment showed that the speed of Plus-X Aerecon decreases almost linearly with increasing temperature. An increase in humidity caused a greater decrease in speed. On the other hand, SO-1213 showed an increase in speed with higher temperatures and also a slight increase in speed with greater humidities. The use of sulfuric acid solutions for humidity control in open receptacles within the test unit may have been responsible for some questionable results. Other means for humidity control need to be considered. In summation, equipment and techniques are described by means of which the reaction of two aerial photographic emulsions to the heat environment of a reconnaissance system may be predicted.