Journal of the Society of Motion Picture and Television Engineers (1950-1954)

banking edges of the film. The edgeflow plates must be slightly thicker than the film to prevent the flow from going over the top of the plates. Locking clamps (Fig. 1 (9)), to lock the edgeflow plates to the heater block, are also used. Splicing of Magnetic Film When splicing magnetic film, it is necessary to replace the stationary and movable knife blades with nonmagnetic materials, Fig. 5. The same procedure is followed for splicing magnetic film as that used for 16mm or 35mm motion picture film. One of the advantages of magnetic film over motion picture film is that the oxide coating does not tend to roll back the few thousandths of an inch which ordinarily seems to be characteristic in splicing motion picture film. When a machine is to be used strictly for 16mm magnetic film, it is advisable to change the location of the index pin so as to splice between sprocket holes rather than through them, as this eliminates the reperforating process. Obviously, there are very few users who could afford to tie up a splicing machine for work on magnetic film only. Therefore, this change is never incorporated unless specifically requested. Frequency tests run on magnetic film disclose the following: A film with no modulation was spliced every 20 ft and recorded on without any wiping or de-magnetizing of the film. No audible noises were noted. An additional film, having a frequency range of from 30 to 15,000 cycles recorded on it, was spliced in each of the various fixed frequencies. This was checked on RCA equipment with the following results: Frequencies from 1,000 to 15,000 cycles — splice was inaudible or at the same level as that of the normal noise of the material. Frequencies from 700 to 1 ,000 cycles — slightly noticeable when the magnetic film was run backward or forward in this range. Frequencies below 700 cycles — inaudible. Strength tests indicated that the splic,ed area was equal to 90% of the tensile strength of the film itself. When 16mm or 35mm standard print stock with a stripe of magnetic material on the side opposite to that of the emulsion is used, it is necessary to change the stainless-steel heater platen (Fig. 1 (7)), to a special stainless-steel, Tefloncoated platen. This prevents the oxide coating from sticking to the heater platen. Splicing of Color Film A number of companies are using this splicer for splicing color raw stock and, again, this Teflon-coated platen had to be used to prevent the antihalation coating present on coated raw stock from sticking. When splicing color prints, it was found that replacing the Teflon tape with a cellophane tape was advantageous. Splicing of Negative Film Splicing of negative 16mm or 35mm film gives exceptionally gratifying results. When prints are made from spliced areas, no indication as to where the splice was made can be noted. No out-of-focus frames are introduced and perfect registration of the picture is achieved without the side shift normally observed as a result of the cement method of splicing. Splicing of Raw Stock By removing the viewing lights or placing a Wratten filter over them, it is possible to splice raw stock in the dark. Previously, splicing of raw stock entailed using the "hit-or-miss" method as to whether the emulsion was completely scraped off, and, therefore, the splicing of raw stock was rarely attempted. Because in the butt-weld 186 February 1953 Journal of the SMPTE VoL 60