International projectionist (Jan-Dec 1936)

November 1936 INTERNATIONAL PROJECTIONIST 25 HAZARDOUS PROPERTIES OF MOTION PICTURE FILM (Continued from page 23) combustion, a potential explosion hazard is introduced, inasmuch as these gases may be ignited later when they reach a supply of air (oxygen). Water Serves Double Purpose It is generally believed that fire-extinguishing systems employing water serve only to extinguish or control film fires; but as a matter of fact, the application of water to decomposing film serves a double purpose, inasmuch as the water reacts chemically with the poisonous oxides of nitrogen, reducing them to nitric acid, which is soluble in water. In a well-sprinkled room in which films are stored, the bulk of the poisonous oxides of nitrogen evolved by decomposition of the film would be chemically acted upon and dissolved by the water. Unfortunately, the poisonous carbon monoxide gas is only slightly soluble in water and can not be effectively removed by this means. It is apparent from the foregoing considerations that when cellulose nitrate motion picture film is used, adequate provision should be made for its safe handling and storage, having in mind the low ignition and decomposition temperature of the film, its extremely rapid rate of combustion, and the possibility of its decomposing with the evolution of explosive and poisonous gases. The importance of complying with the regula tions of the National Board can not be overestimated. Film having a cellulose acetate base was first submitted to the Laboratories about 20 years ago; and as a result of an extensive investigation, acetate-base film in the form of ribbon for motion pictures was listed as slow-burning, the fire hazard being somewhat less than that of common newsprint paper in the same form and quantity. This type of film, however, did not come into general use immediately, probably on account of the superior qualities of the cellulose nitrate film for photographic purposes. Recently, however, the manufacturers of acetate film have succeeded in improving its qualities to a marked degree, and this type of film is now quite generally used, particularly in projectors of the non-professional or miniature type, which may be operated in public without a standard booth if the slow-burning acetate film is used. The ignition temperature of cellulose acetate is between 700 and 800 °F, as compared with about 300 °F for cellulose nitrate. A temperature of about 500 °F is required to produce decomposition of cellulose acetate film. In the neighborhood of this temperature the evolution of fumes occurs. Cellulose Acetate Characteristics The decomposition of cellulose acetate film, however, is riot exothermic, as is the case with cellulose nitrate. In other words, the decomposition of cellulose acetate film once started does not continue except under conditions where OF COLOR When you want to give your patrons all of the beauty and attractiveness of the color that the film contains, just any projection lens won't do. The B & L Cinephor, with its superior color correction, is the lens to use. Combine that feature with the evenness of illumination, greater contrast and increased brightness and you have a lens that will project the type of image that makes a tremendous impression on your patrons. For complete details write to BAUSCH & LOMB OPTICAL CO. 616 St. Paul St., Rochester, N. Y. BAUSCH & LOMB SUPER-CINEPHOR Strong Lamps THE STRONG MOGUL marks a distinct advance in projection arc lamp design and construction, providing many fundamental advantages available only in Strong lamps. Designed to deliver a tremendous volume of light — a steady, brilliant light that is distributed uniformly over the complete screen area, projecting a picture full of depth and definition which fairly sparkles, bringing out all the delicate details and possessing a realistic daylight effect. The higher efficiencies attained through the modern Strong lamp result in a greatly increased volume of light without a corresponding increase in operating costs. THE STRONG UTILITY series of reflector-type projection arc lamps has been designed especially for theatres where economical, flawless projection is required, but where financial conditions limit the original investment. This modern, dependable UTILITY series is comprised of the HI — new low-voltage, high-intensity arc; the LO — regular lowintensity of advanced design; and the AC, efficient alternating current arc. THE STRONG ELECTRIC CORP. 2501 Lagrange St., Toledo, Ohio U. S. A. Export Offices: Room 301, 220 W. 42nd St. New York, N. Y.