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

Chemical Corner Edited by Irving M. Ewig for the Society's Laboratory Practice Committee. Suggestions should be sent to Society headquarters marked for the attention of Mr. Ewig. Neither the Society nor the Editor assumes any responsibility for the validity of the statements contained in this column. They are intended as suggestions for further investigation by interested persons. Foam Prevention Tributyl phosphate has good antifoaming properties and in addition is colorless and odorless. This product is marketed by Apex Division of Food Machinery and Chemical Corp., Niro, W. Va. Substitute British Kinematography has an for Metol article in the February 1952 issue (vol. 20, no. 2) describing a substitute for metol. It is 1-phenyl 3-pyrazolidene. It is white and odorless; and persons sensitive to metol poisoning are reported unaffected by this so-called Phenidone. Like metol it is sensitive to pH and is soft working when used alone. In combination with hydroquinone it gives a more rapid, less grainy image and produces less fog. It also yields a high contrast with hydroquinone and has a lower exhaustion rate. It is possible to match a metol-hydroquinone developer with a phenidone-hydroquinone developer. Construction of An interesting article, Water Purifier "Pure water for your darkroom," in American Photography, (vol. 45, 341-346, June 1951), by H. F. Walton, describes a method for constructing a water-purification, ionexchange unit. All that is required is some laboratory glassware and commercial resins. Try It Before A method for rapid You Buy It identification of nickel alloys, stainless steels, etc., might be of value in the motion picture laboratory where the question of materials of construction of processing equipment often comes up. Such a quick test procedure has been described in a pamphlet by Henry B. Lee of Eastman Kodak and published as Special Technical Bulletin #98 by the American Society for Testing Materials, 1916 Race St., Philadelphia 3, Pa. The metals or groups of metals for which methods of testing are described are nickel, monel metal, inconel, stainless steel #316, other chrome nickel, nickel stainless steels, straight chromium stainless steels as a class, etc. All the requirements for testing are seven common chemicals, a stirring rod, a medicine dropper, a porcelain spot plate and an abrasive cloth. Tank Cleaning Advice L. B. Russell Chemicals, Inc., of 60 Orange St., Bloomfield, N.J., markets a chemical preparation called "Wizz" which is used for cleaning developing tanks. Reported safe to handle, noncorrosive and useful with any type of material, it is dissolved in water. The solution is kept overnight in the developer tank which is then washed out thoroughly to leave the tank free of chemical deposit and crustation. Periodic treatment of developer tanks will add to uniformity of the developer and lengthen its life, eliminate dirt problems and generally improve processing. Film Processing A series of articles by Chemistry various authorities deal ing with some fundamental chemistry of film processing appeared in British Kinematography, vol. 20, no. 2, Feb. 1952. One of these articles discusses the various chemical constituents of a developer and their roles; the chemical reactions of a developer and the products formed . The matter of the dependence of the rate of replenishment on the amount of bromide that can be tolerated in the developer is discussed. It is also pointed out that the work of development is performed by metol while hydroquinone serves to reverse the oxidized metol back to its original functional state and thereby becomes oxidized itself. Therefore, the maintenance of the metol concentration in the developer is easy compared to that of hydroquinone. Some suggestions about electrolytic recovery of silver and the regeneration of hypo are also discussed. 548