Movie Makers (Jan-Dec 1949)

98 LOOK TO YOUR SPLICING It's more than just mechanical, says this able amateur, listing ten points of fine film care JOSEPH J. HARLEY, FACL IN THE several operations of the editing process, splicing is far too often regarded as the country cousin of the craft — so simple that it need not be taken seriously. It is not, I assure you, the intention here to claim for splicing a complexity which it does not and need not have. But if you are bothered by pictures jumping on the screen, by flashes of white between scenes, by losses of loop or even by the film parting during projection — then you'll want to look to your splicing technique. Here are the points to look for. NATURE OF FILM To begin with, let's examine the materials with which we are working. There is first the strip of film to be spliced. This is composed of a transparent ribbon of cellulose acetate known as the film base. Coated on it in turn are one or more layers of light-sensitive chemicals (one layer for black and white film, three for color) known as the emulsion. Between the base and the emulsion is a binder holding the two together, with additional binders between the color layers. ACTION OF CEMENT The second material involved in the splicing operation is a bottle of viscous liquid known as film cement. This is an inaccurate term, since it suggests a simple sticking or gluing together of the two film ends. Actually, film cement is a chemical solvent, and the bond which it effects between two strips of film is a genuine welding of them together. FUNCTION OF SPLICER It is because of the nature of this action that the third material, or tool, of splicing is required — the splicer. For, in its function as a chemical solvent, film cement will act only on the base or cellulose component of the film. It will not act on the emulsion layer nor on the binder. Thus, the first function of the splicer is to provide a means of removing these materials from a short, predetermined area of one film end. This is done simply by scraping away these unwanted materials, until the pure cellulose of the base is exposed. With this done and the cement applied, the second function of the splicer is to hold the two film ends in accurate alignment and in firm contact until the chemical weld is accomplished. With these basic operations clearly in mind, let us now see how they are carried out. PREPARING FOR SPLICE In preparing the films for splicing, they are clamped in the splicer and cut to the correct length of overlap. The film which will be positioned on the bottom of the splice (the left hand strip) will have its emulsion side up ; it is this emulsion which must be removed to a width equaling the overlap. The underside of the right hand film is clear base and can be cemented readily, provided it is free from oil or dirt that may have adhered in projection or in handling. If it has become so soiled, it may be cleaned with a commercial film cleaner or chemically pure carbon tetrachloride. Another method is to spread a bit of film cement on the underside of the film and then wipe it off quickly. But the scraping is the most important operation. Every trace of emulsion and binder should be removed clear down to the film base. USE OF MOISTURE An application of moisture to the emulsion surface will aid greatly in softening it; but care should be exercised to apply this moisture [Continued on page 117] FIG. 1: The multi-layered structure of movie film is shown above. Thick bottom layer is cellulose acetate base, top layer the sensitized emulsion, middle layer the binder. Emulsion and binder must be removed in splicing so thai cement can act on clear base. □ □ □ □ □ □ □ □ □ □ □ □ □ □ iS s □ □ □ □ FIG 2: A sharp scraper blade and controlled use of moisture will give you clean emulsion line at left. Excess moistening leads to jagged scraped edge. FIG. 3: Well aligned splicer pins will superimpose perforations as at left. Splice at right will jump.