International projectionist (Jan-Dec 1948)

NITROCELLULOSE FILM "r: {Continued from page 6) ruonia. sulfur dioxide, and hydrogen sulfide, all. of them active poisons. It was stated previously that the camphor content of celluloid prevents actual explosion of the solid. The camphor also renders celluloid somewhat less violently combustible than pyroxylin, its chief constituent. Now, old film has lost some of its camphor, thus it is more brittle and more dangerously inflammable than new film. The picture image itself, because of its selective absorption of radiation, has an appreciable effect upon the combustibility of film. A dark, or "dense," print absorbs heat more readily than a light, or "thin," print. The application of heat therefore ignites a dark film more easily, but after the combustion has started there is little difference in the way the two types of film burn. It happens occasionally that a film breaks between the intermittent sprocket and the aperture, allowing the intense light beam to strike motionless film. Very seldom, however, does an accident of this sort result in widespread film fire. The frame at the aperture is at once burned out, of course, but the comparatively cool gate conducts heat away so rapidly that the rest of the film never attains its ignition temperature. Chief Causes of Film Fires The experienced projectionist knows the value of precaution in the matter of film fires, but in the majority of theatres the entire burden of film fire prevention falls upon him alone. And where incompetent "hacks" are in charge, the burden is not well borne. The average theatre owner flagrantly ignores the prime sources of danger, i.e., antiquated and worn projection equipment manned by "hacks" instead of by skilled projection specialists. Here is a list of causes of film tires for which the exhibitor is responsible. Defective equipment naturally heads the list, for more than 90% of all film fires may be attributed to this cause: 1. Defective and worn projection equipment. Placement of spark-emitting motors or switches near the rewinder. Torn, brittle, or worn film. The use of a high-amperage arc with a front shutter projector, causing dangerous overheating of the gate. Faulty operation of the automatic fire shutter. Now follows a list of hazardous practices (in no special order) not uncommon in "hack" projection. Since it lies in the exhibitor's power to hire competent projectionists, can he not be con 2. 3. 4. 5. sidered responsible also for these causes of fire? 1. Allowing dirt to collect and jam fire-valve rollers and other projector parts. 2. The use of, matches to probe dirt from a loaded projector. .'}. Incorrect or careless threading of projectors. 4. Bringing film in contact with hot parts of projector when threading. 5. Failure to close the dowser after a shutdown. 6. Failure to close the magazine doors. 7. Dropping hot carbon stubs onto film. 8. Throwing carbon stubs into the film waste can. 9. Smoking in the projection room. 10. Permitting film to come in contact with unshielded radiators or heaters. 11. Hasty and careless repair of prints. 12. Laying a hot soldering iron on the rewind bench or near the film cabinets. The projectionist should ponder this list to make doubly certain that he follows none of these dangerous practices. The danger of fire can be greatly mini mized by retraining from unwinding film on the floor. If a projector takeup fails (but why should it?) the projectionist should never allow the film to feed out all over the projection room floor. Loose film burns hundreds of times more fiercely than a compact roll, and, too, scattered film offers an alarming opportunity for chance ignition. Despite every precaution, accidents do happen. It is almost impossible to give specific advice here except on one point: Do not attempt fighting a film fire with inadequate equipment. Shut off the lamps and motors if you have time, rip the port-slide release, and Get Out of the Projection Room! Carbon-Tet Extinguishers Vetoed A film fire can be put out only by cooling the film below its ignition temperature. Ordinary fires can be extinguished by blanketing the blaze with an oxygen-excluding gas such as carbon tetrachloride vapor, but this is not true of burning film. Film contains its own oxygen. A carbon-tet extinguisher may or may not put out a film fire, depending upon the intensity of the blaze. A hot fire will immediately convert the car D ED ICATE D TO SOUND AT ITS BEST FOR EVERY THEATRE ^ r ONE STANDARD OF QUALITY ONLY . . .THE HIGHEST INFORMATION OF VALUE TO THE MOTION PICTURE INDUSTRY "VOICE OF THE THEATRE" SOUND SYSTEM CHOSEN BY THE ACADEMY AWARD THEATRE TO PROVIDE OPTIMUM SOUND PROJECTION HOLLYWOOD— To make it possible for the sound directors of the producing companies to hear and judge the sound quality of their respective products under conditions that meet the stringent requirements set by the Academy for sound reproduction, the Academy has installed an Altec Lansing standard A-2 type "Voice of the Theatre" loudspeaker system in the Academy Award Theatre. The studios use the Academy Theatre as a "proving ground" for new products as they are issued, since the theatre provides optimum conditions of sound projection. The Altec Lansing A-2 and A-2X "Voice of the Theatre" speaker systems are for use with amplifier power up to 80 watts and up to 150 watts respectively. These systems make 100 percent use of the complete frequency range as recorded 1161 N. Vine Street Hollywood 38, Calif. on the sound track. Ask your supply dealer about the right size "Voice of the Theatre" for your theatre. "Voice of the Theatre" sound systems are supplied as regular equipment by most leading manufacturers of theatre systems^ 250 West 57th Street New York 19, N. Y. INTERNATIONAL PROJECTIONIST • February 1948