International projectionist (Jan-Dec 1951)

Proper Handling of Safety Film SAFETY motion picture film requires no special precautions in handling or storage as far as its own fire hazard is concerned. Underwriters' Laboratories describe approved acetate film as slow-burning and state that "hazards in use and storage are small, being somewhat less than those presented by common newsprint paper in the same form and quantity." Where safety film is used exclusively, only normal fire precautions are required as in any office or building containing paper, wood, or similar combustible material. Safety films should be stored in individual cans in metal cabinets, but these need not be sprinklered or vented. Where safety and nitrate films are both being used in studios, laboratories, exchanges, theaters, or storage vaults, the same regulations and precautions must be followed as if all the film were nitrate. It is, of course, entirely feasible to segregate the work involving safety film alone in any given studio, laboratory, or exchange, so that certain areas might be operated without the restrictions applying to nitrate film. The only real hazard in acetate film is that its increased use will tend to make people careless, and proper safety precautions may be neglected while some nitrate film is still in circulation. If this happens, a serious accident may result. Combination Safety-Nitrate Prints A roll of film which is acetate base at the outside might contain nitrate film spliced in the interior of the roll. A print released on acetate stock may later have replacements made on nitrate stock and be run on a projector not properly maintained for nitrate film. A laboratory which has been using safety stock for release prints for a period of time may suddenly switch to nitrate stock without announcement or warning. The danger of such practices is obvious. Even when no more nitrate film is being manufactured in the United States, foreign negatives or prints on nitrate stock may be imported. Another hazard is the quantity of nitrate negatives and prints in storage vaults, some of which may be kept for 25 years or more. Any such collection of nitrate films that is to be saved should be stored in a separate approved vault, never in the same vault with safety films. , ■ ■ '■ ■:::■:■.--. \ :,: . ■■■ '■ ,:-, ■■■: y/m . ■■■■:■ ■ ' ■ ■■■■: -yy.ii'y ■ : . : ■:■:■:■ i:. .:■:■ ::' I H H r I *1 « I M H J b : I I 'I NITRATE FILM FIG. 5. The visible frame-line mark on raw Canadian by Eastman Kodak Company is to appby a very small amount of a fluorescent chemical on safety film base used for 35-mm motion picture film. When a 35-mm roll of film so treated is viewed on edge under a suitable ultraviolet lamp in a partially darkened room, a vivid purple fluorescence is visible; whereas untreated film viewed in the same way appears black. In white light fluorescenttreated and untreated films look exactly the same. Extensive tests in both the laboratory and the trade indicate that the fluorescent treatment of the base has no detrimental effect on the film before or after development. This simple and effective method of rapidly distinguishing nitrate and safety film in bulk form is illustrated in Fig. 6 which shows a composite nitrate and safety film roll on an exchange reel. The same roll wound on a core is shown in Fig. 7. The nitrate firm appears black and the fluorescent-treated safety film ap and processed nitrate film manufactured by Kodak. pears white in these reproductions. The contrast between the two films is much more striking in actual practice or in a color photograph where the edge of the safety film appears purple. The ex change reel does not permit as complete an examination as in the case of a roll on a core, but it is still possible to tell quickly whether most of the roll is nitrate or safety. A suitable inexpensive ultraviolet lamp in various table, overhead, portable, spot, or flood-light models may be purchased from several manufacturers complete with transformer and filter ready for use.** A 100-watt bulb is recommended for general use, but smaller or larger, ones may be obtained if desired. The ultraviolet bulbs and other parts may also be purchased separately from electrical supply stores and assembled in standard fixtures. The ultraviolet lamp should be equipped with a hood or reflector, and care should be taken not to expose the eyes for long periods to direct ultraviolet radiation from these lamps. Provided such care is taken, ultraviolet lamps present no personnel hazard. They are in constant use in various other industries. (Continued next page, foot of Col. I) ** For example, Switzer Brothers, Inc., 1220 Huron Road, Cleveland 15, Ohio, Black Light Model 103. Figure 6 Figure 7 In Fig. 6 is shown a mixed roll of fluorescent-treated safety film (white) and untreated nitrate film (dark) on an exchange reel. (Photographed with ultraviolet light.) The edge of the treated safety film is actually colored purple, and the nitrate film black in ultraviolet light. Fig. 7 shows the same roll as in Fig. 6 but on a plastic core. 16 INTERNATIONAL PROJECTIONIST • March 1951