International projectionist (Jan-Dec 1952)

mnmmamMMmmmmmmmnmmmnaunm • j ]";y ~\J-'\J"""L.[."-LFT T^LPLr^F^ r*" Safety film identification: In addition to the words "Safety Film" there are horizontal identifying marks located every fourth sprocket hole within the row of sprocket holes along the non-sound edge of the film. those raised by projectionists who still prefer nitrate to the latest high-acetyl safety film. "Safety film becomes brittle and shrinks much more rapidly than nitrate film with repeated projections," volunteered a surprisingly large number of projectionists whom the writer considers as spokesmen for thousands of brother projectionists. These men added, in effect: "When safety film is accidentally pleated or crimped, the resulting creases can seldom be unfolded without breaking the film. Not so with nitrate film, which is sufficiently tough to withstand such misuse." The writer could have gone all the way with these complaints had only the earlier types of safety film been meant. But having projected many reels of all types of film on many makes and models of projection machines, and recalling clearly the extreme brittleness encountered countless times with nitrate film, some of it fairly fresh stock, he began to wonder if projectionists who complained of shrinkage and brittleness had not subconsciously confused the properties of diacetate and acetopropionate safety film — (the earlier types) — with modern high-acetyl safety film. Because, actually, the new safety film shrinks very much less than the best nitrate film, and the new safety film does not become brittle in normal use. The old diacetate (or "low-acetyl") safety film, by the way, was the first type of safety base manufactured by Eastman Kodak. Although acetylated to a slightly higher degree than the "normal" cellulose diacetate (about 34% acetyl) low-acetyl base (38.0% to 39.5% acetyl) is commonly called "diacetate" safety, base. It was introduced by Eastman on a large scale in 1923 for 16-mm home-movie films. Although it was occasionally used for non-professional 35-mm prints, diacetate film was definitely unsuitable for projection by powerful arcs in theatres. It shrank and buckled excessively and became frame-embossed and brittle after only a few runs. Not only that, but it also gave trouble when machine-processed because it swelled rapidly in contact with water, resulting in slack loops, and quickly shrank as it passed over the rollers of the drying cabinets, re sulting in tautness and subsequent permanent deformation of the film. Only the acetates, propionates, and butyrates of cellulose are of practical use as plastics — and these and other kinds of relatively non-inflammable plastics have almost completely replaced the cellulose nitrates (cellulose esters of nitric acid) from which the dangerous nitrate motion-picture films and other "celluloid" articles of yesteryear were made. Cellulose acetate is a cellulose ester of acetic acid alone, and cellulose propionate is a cellulose ester of propionic acid alone; but cellulose acetopropionate is a mixed cellulose ester of both acetic and propionic acids. Acetopropionate safety film was found to be much superior to the older diacetate film. In fact, it was about midway between diacetate and nitrate film in most of its physical properties. Although used successfully during the second world war for service showings, and for all 16 and 8-mm subjects, the few short subjects on acetopropionate base released to the theatres proved that it was unsatisfactory for professional use. It shrank, became brittle, the perforations tore out easily; buckling, focus-drift, and other in-and-out of focus effects were of a large magnitude. So acetopropionate was out for 35-mm filming. But continued research in the safety-film field resulted in a number of experimental films. Of these Eastman chose the high-acetyl (triacetate) film as being best suited for professional use at the present time, and the most like nitrate in physical properties. Modern (High-Acetyl) Safety Stock High-acetyl film was introduced to the trade on an exploratory basis in 1946; and in 1947 it began to be used extensively as a replacement for standard 35-mm release positive stock. The "du Nitrate film identification: In addition to the words "Nitrate Film" there are vertical identifying marks located every fourth sprocket hole in the region between the sprocket holes and film edge. plitized" Trucolor prints released by Republic Pictures were noteworthy as the trade tests which "sold" the industry on the new safety base as soon as its performance-characteristics, first determined by extensive laboratory testing, were verified in the field. The Trucolor trade tests were especially severe, since Trucolor, like other double-coated color positives, nearly doubles the difficulty of splicing. Not only must the blue emulsion on the normal emulsion side of the film be scraped off one stub, but the red-orange emulsion on the reverse side must be scraped from the other stub in order to obtain two film-base surfaces which face each other in making the splice. Projectionist resentment against the new film was immediately evident. Some complained they could not focus it clearly, blaming this defect on the film base, when actually the duplitized nature of the photographic images was at fault. If a good focus cannot be obtained with Trucolor, Cinecolor, Supercinecolor, Magnacolor, etc., it is simply because it is impossible to bring both sides of the film to a focus on the screen. The best that can be done with 2-color duplitized prints is to bring the blue or cyan image to a focus; with 3-color duplitized prints, the magenta image. Especially annoying, however, were the black-and-white "sneak" tests, wherein black-and-white films were handed to the projectionist without adequate instructions for splicing them, or even furnishing cements which would "take" on high-acetyl base. For example, one of the earliest trade tests consisted of features, the first two reels of which were printed on one kind of stock, the next two on the other, etc. While tests such as these verified the serviceability of high-acetyl film, they also gave the projectionist a slap in the face which he could hardly be expected to appreciate. From the raw-stock manufacturer's point of view, "sneak" tests were nevertheless necessary to reveal any defects which might turn up under actual theatre usage. Happily, safety film held up remarkably well in comparison with nitrate stock, and was even superior to the latter in several important respects. But breaks in the show, due to safety INTERNATIONAL PROJECTIONIST December 1952