Journal of the Society of Motion Picture and Television Engineers (1950-1954)

lamples were then removed and put in k tray containing fixing bath and later Ivere put in a normal wash tank with running water. A number of samples Ivere also developed under condition of rcontinuous agitation." These samples Lvere again fixed in a regular tray and kvashed in a regular bath. The same brocedure was also followed after the Completion of a run of tests and before the particular developer used in the tests was thrown away. These control [tests gave a close check on any small variations in the properties of the developing fluid. All samples were properly marked during the tests so that identification was possible after the samples had been washed and dried. The washing of all samples was done in the regular running water tray bath for a period of at least one hour and the samples were then dried by hanging them up on a line. The densities of the exposed wedges were read on a densitometer. The film used during the entire tests was Super XX Aerographic film which was cut up into small samples approximately 6 in. long and \\ in. wide. These film samples were exposed to a photographic wedge in the sensitometer at Boston University. The film samples were kept in a light-proof box in the darkroom and were usually used for the tests within a day or two after exposure. A number of different channel heights were used in the tests with the different channels as described previously. In addition, for each channel the pump speeds, and consequently the flow rate, through the chamber were varied considerably by means of the variable speed drive contained in the system. The temperature of the operating fluids was accurately maintained by means of an independent temperature control system. This system consisted of separate thermostats for each tank, operating a solenoid valve which introduced cooling water through the cooling coil in the tank. The temperature variations of the fluids as observed were approximately ±J°. The temperature was maintained at 68 F. Turbulent Fixing. Turbulent fixing tests were performed in the following manner: A strong light was mounted behind the turbulent processing chamber and the observer placed himself on the other side of the chamber, so that he could see the sample mounted in the chamber with the light shining through it. Turbulent fixer was then passed through the chamber and the observer noted the time required for the sample to clear completely. As soon as the sample was completely cleared the observer would notify a second observer who noted the exact time elapsed. All the different channels were used in the turbulent fixing tests under different conditions of flow as observed in the flow meter and the pressure gages. "No agitation" fixing and "constant agitation" fixing tests were performed to check on any variations in the fixing bath. The samples used were not developed to eliminate variations introduced by the developer. Turbulent Washing. For the turbulent washing tests a sample was first developed in a tray under conditions of "no agitation," then fixed in a tray under conditions of "no agitation." The wet sample was then mounted in the turbulent developing chamber and turbulent water was passed over the sample. It should be noted here that the water used for turbulent washing was recycled but fresh water was also added continuously during the test. After a fixed period of time, as determined by the electric timer, the water flow over the sample was shut off, the sample was quickly removed from the chamber and mounted in a test tube containing silver nitrate. The sample was then vigorously shaken until a deposit was formed and the amount of deposit was compared with a number Katz and Esthimer: Turbulent Fluid Processing 119