Society of Motion Picture Engineers : incorporation and by-laws (1927)

536 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 the preliminary tests. Since carbon tetrachloride is non-inflammable and when pure has no harmful effect on the film, this solvent was used exclusively in the later tests. Properties of Motion Picture Film With a Coating of Wax over the Entire Gelatin Surface 1 . The Projection Life as Compared unth Edge Waxed Film Comparative measurements were made on the projection life of the various samples of waxed film as follows: The ends of a 6-foot length of each sample of film were spliced together so as to form a loop, and this was run continuously through a Powers projector maintained as nearly as possible under standardized conditions. The gate spring tensions were checked at regular intervals, and the machine otherwise maintained in first class condition. If any incrustation tended to form in the gate, this was indicated by a distinctive noise and the incrustation was at once removed. The number of times which the film passed through the machine was recorded by a counting device, and projection of the film was continued until perforations became torn to such* an extent that the film would no longer pass successfully through the machine. Assuming a basis of 100% projection life for normally processed film which was not treated in any way before projection, the results of tests with films lubricated over the entire surface with various waxes were as follows: Nature of Wax or Oil Solution in Carhon Tetrachloride Projection Life Plain film (untreated) 100% Montan 1 % 77 Montan 5% 94 Turpentine 100 Carnauba 5% 125 Johnson's floor wax 6% 185 Beeswax 260 Paraffin 1% (M. P. 130° -140°r.) 310 Paraffin 2 partsl ^^^ Carnauba 1 part/ ° 380 Paraffin 2 parts\ ^ Carnauba 1 part/ 480 Paraffin 5% 850 Eastman edge waxed film 950