Journal of the Society of Motion Picture Engineers (1930-1949)

Record Details:

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March, 1930] BLOCKING OUT SPLICES IN SOUND FlLM 351 and a very irregular edge was produced. This effect did not occur when a thick lacquer was used, or when very small quantities of the thin lacquer were applied repeatedly, but this procedure was so slow as to be of no advantage. It was then considered that an opaque sticker or patch of suitable material and design could be applied rapidly enough for this purpose. A gummed paper patch was first tried. This could be applied readily and eliminated the splice noise, but became brittle and sometimes peeled off after the film had been projected a few times. Decalcomania transfers were also tried but found unsuitable. These transfers as purchased consist of a sheet of material, 0.001 inch thick, attached to a thick paper. They are soaked in water and the transfer then floated off onto the gelatin coated side of the film. This type of patch dries too slowly and does nbt become intimately attached to the film in the region of the splice, because there is no fusing together as with a cemented patch. An opaque film was then made by incorporating dye and pigment in motion picture film base, but when the cement was applied to patches made from such film they curled excessively. A critical thickness of four-thousandths of an inch was necessary in order to prevent curling. This thickness was considered excessive. If the film base was coated with a gelatin layer, this materially reduced the curling tendency. The film patch material finally adopted consisted of clear film base, emulsion-coated, and rendered opaque by exposure and development. A film of minimum thickness (0.003 inch) was chosen so as to conform readily to the irregular surface of the splice and prevent the splice from becoming too thick and stiff. This type of splice (Fig. 2) was very successful. The patches were tested by applying them over splices in a positive film which was then run through a projection machine until the film broke down completely. The patches were intact up to the time when the perforations commenced to fracture at the corners. The Splicing Operation. — The patch is applied with the aid of a registration block shown in Fig. 3. This consists of a bed plate fitted with registration pins and a pressure platen fitted with a rubber pressure plate. The platen is hinged to the bed and the rubber pressure surface is cut out so that it fits closely around the pins. The motion picture film is placed on the registration block with the support side up and that side of the strip which bears the sound record