Business screen magazine (1946)

13ECENT severe fire lu!>ses tu ■*■*■ motion picture film and storage facilities have resulted in investigations which prove that spontaneous ignition of cclluh)se nitrate fihn can occur when such film is in an advanced stage of decomposition. While the business fihn industry has converted to safetv film, it is estimated that some hundreds of nitrate motion picture negatives remain on hand in film libraries and company storage vaults across the country. These old negatives (and some nitrate prints too) constitute a definite fire hazard if they are not carefully checked for signs of advanced decomposition. During the initial inspection of film storage facilities, it is possible that a relatively high proportion of nitrate films may be found in advanced stages of decomposition. When the subject matter is important, the film should be copied and the original destroyed: if the material is not valuable, the film should be destroyed at once. Nitrate Ignites Spontaneously Prior to the recent investigations by the .National Bureau of Standards, it was generally believed that nitrate film would not ignite spontaneously at temperatures ordinarily encountered in a film vault. But tests made by the NBS Fire Protection Laboratory have shown that spontaneous ignition is an inherent hazard of old nitrate film. In the tests, samples of nitrate films in various stages of decomposition were supplied by the National Archives for the purpose of simulating conditions which may have prevailed at the fire locations. These samples were stored in a special chaml>er, the temperature of which was controlled and recorded. Each film was packed in an individual can which was in turn wrapped in mineral wool to retain the heat of the decomposition reaction. The temperature in the chamber was initially 95 degrees and then it was increased slightly at intervals, but always maintained below that of the reacting film. Temperature Kiiild" I p At a chamltcr tem|)erature of 106 degrees, one roll of film in the more advanced stage of decomposition was found to \>c increasing in temperature at an accelerating rate. On the 17th day of storage, with the chamber temperature still at 106 degrees, ignition of the film occurred. Its temperature at the lime had reached 14f) degrees. With the chamIx'r held at 120 degrees, another 42 Old Nitrate Films Present Fire Hazard m KKM OF STANDVKDS ADVISES CHECK OF OI.DEH FILMS case of spontaneous ignition occurred when a roll caught fire after self-healing lo ISO degrees. (^ool Air Kriliices Ha/.ard Because the number of samples investigated was small, it is doubtful whether 100 degrees is the lowest l<'mpcralurc at which a reel of deteriorating film will self-ignite. The results obtained in the .NBS tests indicate that good film does not self-ignite at ordinary storage temperatures. In one of the government film di'positories, large quantities of cellulose nitrate film have been stored in standard vaults in which the temperatures are maintained at about 70 degrees b\ an air conditioning system. Several inspections of film in thi-i^L vaults did not reveal evidence of serious film decomposition. Relatively low temperatures will materially decrease the possibility of a fire by spontaneous ignition and at the same time preserve the film for its intended purpose. Heniovc Deteriorating Film The logical approach to safe storage is the removal of all film showing signs of deterioration. Such film can readily be found by scheduled inspections of stored film stocks. Inspection personnel should be trained to recognize decomposing film by appearance, and to DE FRENES 1909 BUTTONWOOD STREETPHILA. 30, PA. RIttenhouse 6-1686 35 MM-16 MM -COLOR -BLACK & WHITE SOUND SYSTEM ilassify its condition according the following categories. In the first stage of detcrioralio the photographic portion usual shows an and)er discoloration wit fading of the picture image. In ll' second stage, the emulsion lK,'comi adhesive and llie film tends to sti< together during unrolling. Examples of Decomposition Film in the third stage of d lerioration has portions which a. soft, contain gas bubbles and em a distinctive noxious odor. In tl fiiurlli stage, the entire film is sol it ina\ be welded into a single mat and frequently its surface is CO ered with a viscous froth. A stron odor is in evidence. The film ma; degenerates partially or entirel into a brownish acrid powder in tl fifth and final stage. When films in the third, fourt and fifth stages of decompositio are designated for disposal, the should be submerged immediatel in water-filled drums, carried t remote area and destroyed by bun ing. The ground on which the fill is to be burned should be free c brush, grass, leaves or other litte Precautions for Burning Burning should be confined t batches of not more than 25 pound because the heat from large amounts of film creates a stron updraft which may bear fragment of burning film considerable di tances. thus endangering neighbo! ing ])roperties. I nder no circumstances shouli films be burned in an inhabitet area or within a building. The rapii production of gases during th' burning makes it extremelv danger ous. particularly if the film burned in a furnace or confinet space. During test fires in a wdl ventilated vault, engineers record pressures as high as 18 pounds pe; s(]uare inch. No ordinarv furnaci structure could withstand such pres sure; its breeching would fail, thui filling the furnace room with flame and |)oisonous gases. H Passenger Liner Will Feature Two Motion Picture Theaters ♦ I he giant passenger liner. SS I nited States, largest ship ever launched in this countrv. is now licing outfitted with two complete i>uilt-in motion picture theaters which will show manv sponsored films. lU'A motion picture projection and sound reproduction equipment will be installed in time for the ves -el's maiden trans-Atlantic run next spring. BUSINESS SCREEN MAGAZIM