Emulsion clearing characteristics in the processing of dental radiographic films

Recent problems in the fixation of dental X-ray films during processing have led to a study of the clearing of dental emulsions. A method has been devised to compare the behaviour of different emulsions and fixing chemistry under varying conditions of time and temperature. The ease with which emulsions clear has been shown to relate to the fixer chemistry, temperature and time of fixation and, for D-speed films, to the speed of the emulsion. The density of the residual silver halide is approximately inversely proportional to the time and temperature for the ranges explored. E-speed emulsion was less affected than D-speed by fixer chemistry, time and temperature. Fixation is relatively less influenced by temperature changes than development. A suspected relationship between clearing ability and emulsion thickness has not been demonstrated reliably in this investigation. The evaluation of these variables is of relevance to those concerned with the manufacture of films, processors, and processing chemistry as well as to those who process X-ray films.