International projectionist (Jan-Dec 1939)

Film Preservative Tests AN ABSTRACT OF A REPORT BY RELEASE PRINT QUALITY COMMITTEE RESEARCH COUNCIL, ACADEMY OF M. P. ARTS & SCIENCES TREATMENT given to release print film after it has been printed, developed and dried is commonly called "film preserving," and the processes by which this treatment is given are known as "film preservative" processes. The gelatin of freshly developed film carries a high percentage of moisture in its pores, and as long as this condition prevails is known as a "green" emulsion. A so-called "green" emulsion is quite soft and the slightest abrasion will cause a scratch. These scratches widen out as the gelatin dries, and cause the "rainy" effects seen on the screen in the theatre. As film with "green" or soft, emulsion passes through a projector, it leaves small deposits of emulsion on the tension shoes at either the aperture plate or the sound gate,, unless the tension shoes are Tcept thoroughly lubricated. Such deposits build up resistance to a free passage of the film over them, and scratch the film during projection. When the moisture in a "green" emulsion is withdrawn too quickly, the gelatin shrinks and the film warps or buckles. If too great an amount of moisture is -withdrawn from the gelatin, the film becomes brittle, loses its pliability and is easily torn while being projected. Any treatment offering a preventative of the above conditions must be applied to the film after it has been printed, developed and dried. A film preservative treatment for release prints should: (1) Prevent scratches in new or green emulsion. .'..'.' •', (2) Thoroughly lubricate the emulsion so that it will not adhere to any part of the projector. (3) Impregnate the gelatin with a fixed chemical which will not be dissipated by the intense heat of the projection lamp, but will take the place of the moisture that is withdrawn to thus prevent warping and buckling. (4) Retain the film's pliability indefinitely. • The Test Procedure It was decided that a comparative test of the commercially available preservatives could best be made by including in one reel a sample of release print treated by each of these processes, and subsequently subjecting this test reel to release print film projection under actual theatre conditions. A 2000-foot reel of film was secured from a regular release, cut into 200-foot samples and each sample subsequently treated by one of the following preservative processes: Consolidated edge waxing. Eastman cold waxing. Gage process. Metro-Goldwyn-Mayer edge waxing. Paramount process. Peerless process. Perfexit process. The reel also included one 200-foot sample of unprocessed release print*. This test reel was then subjected to approximately ten months actual theatre use. The reel was projected in all types of theatres, — first, second, third run city theatres, and subsequent run neighborhood houses, so selected that the reel would be projected in theatres equipped with all types and makes of projection equipment. This film was mounted on a standard commercial 2000-foot reel and was transported from theatre to theatre in a regulation I.C.C. shipping case by various available commercial transportation facilities. It was received and handled by the theatre projectionist in exactly the same manner as an ordinary release print and was projected in each theatre from two to six times (depending upon the time available in each particular theatre for this test), upon each of the projectors installed in each theatre. In other words, the reel was subjected as closely as possible to the conditions *It should be noted that the above listing of processes tested is alphabetical and bears no relation to the order of listing in Table A. to which an ordinary exchange release print is subjected. Under these conditions, the reel was projected a total of 439 times. The film was then examined (1) being inspected by projection (2) cleaned and reprojected (3) inspected by hand (4) measured for shrinkage and (5) tested for surface hardness. • The Analysis Procedure This analysis indicated the following conclusions: The first inspection by projection showed the film to be filled with dirt, scratches and oil, and each of the samples appeared to be in very poor condition. The first and last samples on the reel were in the worst condition, as would be expected, due to the handling of the film in threading and rewinding. After the Test Reel had been cleaned several times and reprojected, the conclusions from the first observation were revised because of the fact that the true condition of the film was obscured by dirt and oil. The film was in much better condition than was first indicated. The amount of oil on the film was more objectionable than the scratches remaining on the film after cleaning. The tabulation in Table A shows the results of the various observations in a fairly concise form. Shrinkage measurements were made with the Paramount Film Gauge. This gauge is accurate to within .001" in 3', and has been calibrated against both the Eastman and Dupont gauges. The hardness test was made by drawing the film between a flat surface and a steel point with adjustable weights, set to provide various pressures. A certain pressure is applied on the steel point and increased until the steel point starts abraiding the film. The good samples, with 3 pounds of weight on the steel TABLE A. Ret tilts of various observations on test reel Process Projection Before Cleaning Projection After Cleanina Hand Inspection Hardness Center Edge Shrinkage in 1 Foot Sample No. 1 Dirty and pitted, particularly at beginning. Fairly free of abrasions, except beginning. Beginning badly pitted and short scratches. Fair. Good. .062" Sample No. 2 Fairly clean. Fairly free of any noticeable abrasions. Less scratches than No.l. Poor. Good. .066" Sample No. 3 Fairly clean. Fairly free of any noticeable abrasions. Long scratches in center of film. Poor. Good. 066" Sample No. 4 Dirty and pitted. Fairly free of any noticeable abrasions. Long scratches in center of film. Poor. Good. .067" Sample No. 5 Dirty and pitted. A few long scratches in center. Better than No. 3 and No. 4, but some short scratches. Good. Good. .065" Sample No. 6 Fairly clean. Fairly free of abrasions. Some long scratches Fair. Good. .066" Sample No. 7 (Unpreserved) Dirty and pitted. Long, heavy scratches. Long scratches heaviest on this sample. Poor. Good. .065" Sample No. 8 Beginning good, end full of short abrasions. Beginning quite free of abrasions. Fair. Good. .057" 20 INTERNATIONAL PROJECTIONIST