International projectionist (Jan-Dec 1958)

lubrication and tension adjustment. Avoid unwinding film on the floor: clean all lengths of film so mistreated. Short lengths may be cleaned between two soft pads of lintless felt with a volatile, non-toxic, non-inflammable cleaning fluid which does. not soften or curl the film. Carbon tetrachloride, without doubt the most effective filmcleaning fluid, is too dangerous for use in cleaning film by hand. Death has resulted from excessive exposure to carbon tet.* Use a hand-driven rewinding set and draw the film through the moistened pads slowly to give the fluid time to evaporate before the film reaches the reel upon which it is being wound. Keep the pads very moist, and discard them before they have become too dirty and oily. Long reels of film should be refreshed in film-cleaning machines, not by hand methods. Companies specialize in this work for 16-mm users — in addition to cleaning the film, removing all grime and oil-mottle, they are prepared to "scratch-proof" the film with special lacquer treatments. Your Choice Anent Splicing As shown in Fig. 3, the two films to be joined are cut to include a perforation in the overlap area. The emulsion is scraped from the overlap area of the film stub, care being taken to remove the clear gelatine bonding layer next to the celluloid base. If the emulsion is moistened for easy removal, use a sharp razor blade or similar instrument for scraping. A rt^fis^Sr«SSx*!!!sr^^ * See excerpt from Journal of the SMPTE (Sept., 1958, Vol. 67), for exhaustive presentation of film-cleaning agents, tables from which, with explanatory note, appear on page 14. and £S to our Many Friends Everywhere &ss«b»»b!W^ small sandpaper block is used in "dry scraping," a very convenient method. Apply an ample quantity of triacetate safety-film cement to the scraped area in one brush-stroke, then quickly join the two ends of film in registration, pressing them together firmly for 10 or 15 seconds. Be sure that the safety-film cement is formulated for triacetate film, the only kind of film base now manufactured in 16mm size. Older types of cement may not work well. As an alternative to conventional methods, the 16-mm perforated Mylar tape, mentioned earlier, may be used for "butt-splicing" film and repairing torn sections to avoid the necessity for cutting and losing precious frames. Film Care, Splicing Technique On the whole, 16-mm film is an excellent motion-picture medium for all non-theatrical uses, and offers the advantage of great equipment portability, compactness, and light weight. weight only film the 2/llths of the same 16-mm film has of 35-mm nning time.) Much film damage can be prevented IP Cut film as shown Scrape stub Apply cement th**' ■Join and press for 10-15 sec. FIGURE 3 Steps involved in splicing 16-mm film. Note that the film is not cut on a frameline, as ir mm practice. 35 by frequently cleaning the tension gate and sound-drum of the projector. Deposits of hardened emulsion inflict severe scratches on film, and should be scraped from the film-contacting parts with an orangewood fingernail stick or, for the stubborn deposits, a "chisel" of soft copper wire. Do not use steel tools for scraping off emulsion deposits. Steel may scratch the polished surfaces and result in serious damage to the film. Toothed sprockets, sprocket shoes, idlers, and snubber rollers are best cleaned with a toothbrush lightly moistened with kerosene. Lighter fluid (naphtha or gasoline) may also be used if care is taken not to splatter it all over the machine. Guard against getting oil or fluids of any kind on the sound lenses, exciting lamp, or photocell! The perforations of 16-mm film are not as durable as those of 35-mm film; there aren't so many of them! Moreover, the use of claw-intermittent movements contributes to perforation wear. Although claw-shuttles are extremely precise in pulldown action, they have a tendency to become hooked. When a hooked claw disengages from the film, it literally "saws" across the edge of the perforation, tearing it. RCA "400" 16-mm projectors have Stellite steel pulldown claws which do not wear into a hook shape, and never need be replaced because of wear. The Kodascope Pageant projectors employ a claw-tooth of tungsten carbide, one of the hardest substances known. This is also "hook-proof." The art of splicing 16-mm film should be mastered at the outset. A good splicing block should be used, inasmuch as hand-made splices are seldom evenly scraped or perfectly registered. The width of the overlap varies, depending on the make and type of splicer used, but 3/32 inch (2% mm) is customary. 22 INTERNATIONAL PROJECTIONIST DECEMBER 1958