American cinematographer (Jan-Dec 1926)

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Sixteen AMERICAN CINEMATOGRAPHER July, 1926 PROJECTION (Continued from Page 0) on the film holds this dirt and more or less dissolves it. As the film is run through one projector after another, it picks up more dirt and receives more oil until it reaches a point of saturation, resulting in this foreign substance forming a cataract on both the emulsion and celluloid sides of the film. There are none of you but that realize the importance of a reception of lights and shadows on the screen, unmarred by a soiled or dusty screen, dirty or sooty condensor lens, oil or dirt spots on the projection lens, or a hazy reflector in the lamp house. All these are under the control of the projectionist and can be totally eliminated through his efforts, but he is not equipped to remove dirt and oil from the film. As a result the screen presentation is marred in practically all instances where the film used has had five or six prior bookings. Handicap You can visualize some beautiful scene as viewed through a window, or through eye glasses which are covered with a film of oil and dirt. Magnify that condition by the ratio of the motion picture frame to the screen. The apparent results present the handicap that the projectionist attempts to overcome through higher lamp amperage, etc. In the foregoing, I have tried briefly here to outline the cause and effect of dirt and oil on film. Going back to the beginning of my experiments in film cleaning, I will say that I've learned from them that the chemical or wash solution used is of vastly more importance than its application. Requirements In helping to build a proper wash solution, we found first that we wanted one that would remove all oil and dirt fast enough to suit the demands of any vehicle of sufficient capacity. Next, a non-inflammable fluid was necessary, and no inflammable or explosive gasses could be present. It had to be free from all salts and alkalis that would have attacked the silver salts in any way. There could be nothing in it that would attack the emulsion in any manner. It could not give off any gas that would impair the health of the cleaning operator and its cost had to be within a reasonable figure, and above all of these things, it had to revitalize the celluloid stock instead of devitalizing it. We have been able to secure such a solution and are using it today in our department, with satisfactory results in all of these features. After our problems were solved in securing a satisfactory wash solution, we then had its application to consider and were fortunate in getting the manufacturer of the most acceptable machine then on the market, to agree to go through a period of trials and experiments with us. He agreed to any changes in his machine that he and we found would make it more adaptable. As a result of these experiments, we have a machine that does the work satisfactorily, quickly and inexpensively. This cleaning unit consists of one double cleaning machine, described later, and one film splicing machine, and an inspector's work table. Capacity Per Hour The cleaning operator can easily clean twelve to fifteen reels an hour on this double machine. As they come off the cleaning machine, they are handed to the inspector for inspection, the reels bands are placed on the reels and the work is then completed and ready to be placed in the vaults. Thus approximately one hundred reels are cleaned a day with the one machine. How Operated To describe the operation of the machine used, the film is passed first through a bath of the wash solution, about eight inches being submerged at a time. There are felt brushes submerged in the liquid that brush both sides of the film. The film then travels up through the rubber wipers, suspended on a spring at the same angle — very much in the same manner as a window cleaner uses his "sqeegee" in drying the water from a freshly washed window pane. The film then passes through or between flannel strips, slowly driven in an opposite direction to that which the film is traveling. The points of contact with these strips are arranged at offsetting points so that the tension of the film is sufficient to thoroughly polish it on both sides. It then passes through two rubber rollers, wringer-like, which is the only driving power or draught the film has in the entire operation and the film is then wound on a reel by an automatic take-up of the same principle as the take-up on the lower magazine of a projector. The entire operation requires about four and one half minutes to the thousand foot reel of film. (continued on page isj