Motion Picture News (Sept-Oct 1918)

1742 Motion Picture N ew i C a^rrt er ei Labor a*tory Pi ct \xv e N/1 ctlc 1 TV ^4 Portable Apparatus for the Development of Motion Picture Film at High Temperatures By J. I. Crabtree Communication No. 74 from the Research Laboratory ok the Eastman Sodas company (Continued from last Keek) The Developing Tanks These are shown in Fig. 4 and consist of three tanks, T-l, T-2 and T-3, T-l being without cover and fitting into T-3, fitted with a cover and removable screw caps S-l, S-2. The tank T-3 in turn fits into T-2, likewise fitted with a cover. The tanks are nickelplated and fitted with turn-up rings at L-l, L-2 and L-3 to facilitate the rocking of the trays when full of solution. The capacity of each tank when containing the reels averages about 8 liters, or 2 gallons. ... . L IV r S' 13 T* Ti Fig. 4 Method of Development The apron enclosing the exposed film is moved from reel B and placed in the tank T-l containing the special developer T-6, lifted up and down once or twice so as to remove air hells, and the tank then rocked in alternate directions for V/2 minutes at 95° F. or 3 minutes at 85° F., or for the required time in a developer containing sodium sulphate. The apron is then drained quickly and immersed for one or two seconds in T-2, containing rinse water, at the same temperature as the developer in T-l, lifted out, drained and then immediately placed in T-3. T-3 contains the fixing bath, at the same temperature as the liquids in T-l and T-2, and is of course kept covered when containing the formalin fixing bath. The following chrome alum bath is used at temperatures up to 85° F. : Avoirdupois Metric Hypo 7 ozs. 200 g. Sodium Sulphite (desiccated) 1 oz. 175 grains 40 g. Chrome Alum 2 ozs. 350 grains 80 g. Acetic Acid (2870 150 minims 10 cc. Water to 32 ozs. 1 liter Dissolve the sulphite and chrome alum together and add to the hypo solution, finally adding the acetic acid. At temperatures up to 95° F. the following formalin bath should be employed : Avoirdupois Metric Hypo 9 ozs. 250 grams Sodium Sulphite (desiccated) 1 oz. 350 grains 50 grams Formalin (formaldehyde 40%) 4K ozs. 125 cc. Water to 32 ozs. 1 liter First dissolve the hypo, then the sulphite, and finally add the formalin. In ordinary practice with large racks and tanks the odor of formalin in most cases prohibits its use, though with the above outfit and using the covered fixing tank (see Fig. 4), the odor of the formalin is negligible. The tank T-3, fitted with a cover and removable screw caps, S-l and S-2, may be filled through S-l and emptied through S-2. The tank should be kept covered, and the lid removed only to allow of the immersion of the apron. It is advisable to wear rubber gloves when working with formalin. Washing After thoroughly fixing, the apron is removed to tank T-2 and thoroughly washed in several changes of water at the same temperature as the/fixing bath. Washing may be carried out with a minimum amount of water by three or four immersions of 3 minutes each, and rocking and draining after each immersion. Drying Several methods of drying film were tried, as follows : (a) The apron was telescoped over a long rod and allowed to dry in the air. In this way the film was dried in contact with the apron and could be separated from the same when dry. However, by this method the first few feet of film are invariably scratched by virtue of pushing out the center of the roll. If a "leader" is used, scratching of the exposed film may be avoided. (b) By blowing air through the spirally wound apron, thus drying the film in a manner similar to that employed for the drying of prints by means of the Majestic print diyer (EKCo.)A The method of procedure was to place the apron within a funnelshaped holder fitted with a rubber sleeve so as to fit tight around the coiled apron and to blow hot or cold air through the aprort by means of a fan. The experiments were not successful because drops of water were invariably left on the film, and these left drying marks oil, the finished film. From this it was considered absolutely neces^i sary to squeegee the film and remove superfluous moisture beforri drying if drying marks were to be eliminated. Attempts were then made to squeegee the film by re-reelingf the apron and film from reel A to reel B (see Fig. 2) and passing the film between squeegeeing rollers affixed to a spring so as to take up the slack formed by expansion. Although after squeegeeing in this manner better results were obtained, it was considered that owing to the bulkiness of the fan required to supply the air this method was not practicable. The method finally adopted for drying was simply to re-reel the apron and to wind the film on to a collapsible rack similar to thei racks used in the tank development of motion picture film. The surface moisture was removed from the film with a chamois before drying, the film being sufficiently hardened to permit of suchtreatment. If the washing was not thorough a little residual hypo was left on the back surface of the film owing to contact of the same with the apron, though this was removed during the usual process of after cleaning. The apron was readily dried by hanging up in the coiled com dition, though it was not found necessary to thoroughly dry the apron before reeling a new length of film for development. Development of Positive Film The apparatus may be used for developing motion picture posi-j tive film in exactly the same way as for negative film. Portability of the Apparatus The apparatus is extremely portable, the reels, apron and tan» fitting into one tank, as shown in Fig. 5, while the base of the reeling apparatus is made in two parts, which fold together. a* illustrated. The diameter of the reels for different lengths of film is follows : Length of Film Diameter 100 feet 14 inches 150 feet 17 inches 200 feet 20 inches An outfit for finishing 200foot rolls would therefore only take up a space of 22 x 9 inches. Summary By an application of the apron method of developing film as adopted in the Kodak Film Tank outfit a portable and compact i