The international photographer (Jan-Dec 1933)

Fourteen The INTERNATIONAL PHOTOGRAPHER April, 1933 Report of the Committee on the Care and Development of Film (Reprinted by request from the Journal of the Society of Motion Picture Engineers, No. 3, Vol. 20, March, 1933) Sub-Committee On Laboratory Practice The following report, reviewing the conditions as actually found at present in the field, is intended as an introduction to a more detailed and technical study of laboratory practice, to be reported on later. All the phases of handling and treating both unexposed and exposed film in laboratories are discussed, beginning with the testing of the raw stock as received by the laboratory, passing through the exposing, developing, fixing, washing, and drying of the film and concluding ivith duplicating and several subsidiary operations. Following the initial xvork of the sub-committee represented by the studies of existing conditons described in this report, the sub-committee /in, pases in the future to report separately on each of the above named phases. Outline A, Testing; B, Exposing; C, Developing; D, Fixing; E, Washing; F, Drying; G, Conditioning; H, Cutting; /, Printing; J, Duplicating; K, Seasoning. Summary Testing. When producers of motion pictures began to record sound on film in addition to the scenes, the problems of processing became more involved. Factors that had been allowed to vary with impunity had to be maintained constant, and sensitometric equipment, requiring for its operation trained men, had to be installed. New emulsions were prepared in the attempt to obtain a higher quality of picture and sound records. Exposing. The theory of sensitometry is quite explicit in defining the proper exposure of the negative. However, no standard rules of exposure can be strictly adhered to in producing motion pictures owing to the numerous variations in working conditions and the many special effects desired. The greatest degree of coordination is required between the cameramen and the laboratory technicians if the best quality pictures are to be obtained. Developing. In order to increase the quantity of film processed and improve the quality of the product, machines are now used in all large laboratories for developing film. Three methods of controlling the process, or various combinations of these three methods, are usually employed: (1) sampling, (2) time and temperature, and (3) sensitometric. Each of these methods has its own advantages. Fixing. Alum fixing baths are most commonly used, as they require very little attention. The motion of the film through the bath usually causes sufficient agitation of the solution to assure sufficiently complete fixing. Washing. In most instances the tap water runs directly through the washing tanks to the drain. In some few locations it may be necessary to cool the water during the warm season. Drying. Conditioned air of the proper temperature and humidity is circulated through the drying cabinets. The curl of the film usually provides an index of the proper conduct of the drying procedure. Conditioning. To prevent the accumulating of dust and dirt on the film, only conditioned air is admitted into the developing, printing, and assembling rooms. The improvement in the quality of the film, due to guarding it against dirt and scratches, has more than offset the cost of the conditioning equipment. Cutting. The introduction of the sound negative demanded a new technic in cutting and assembling. The addition of music and other kinds of sounds requires thorough technical training of the cutter. Printing. Several types of mechanical devices are now used to determine the proper printing exposure. The uniformity of development that occurs in developing machines is an important factor that assists in properly determining the exposure of the negatives. Trained technicians maintain the exposure scales of the printers constant and uniform. Duplicating. Special emulsions and printers are used in attempting to match the quality of the duplicate print and that of the original print. The contrast can be matched by appropriately developing the film, although graininess may increase and loss of definition occur. Seasoning. Many patented methods are in vogue to protect the film and lengthen its useful life. The most common method of seasoning consists in applying about the perforations a small quantity of wax, which decreases the friction and the tendency to tear during the process of projecting the picture. It is here purposed merely to describe briefly the methods generally employed by the industry in the development and care of film. Thus, the committee submits this report to the Society with the desire that it be considered as an introduction to the reports to follow, in which the respective operations in this field will be studied individually, both from the standpoint of actual practice and from the existing literature. At the completion of such a survey of each operation of the producers in converting an emulsion into a finished print, and distributing the print to the exhibitors, the Committee will be in a position to attempt to make recommendations for the standardization of laboratory and exchange practice. On examining the bibliography in this field, it was found to be extremely lengthy. Thus, rather than attempt to present a general bibliography in this report, it has appeared advisable to subdivide and list the literature in later reports with the respective operation to which it pertains. In this general discussion, it may frequently appear that the report includes subjects outside the purview of this sub-committee. However, it was concluded that any factor such as the characteristic of the emulsion or the nature of the exposure that might affect the quality of the finished print should be considered. The quality of the laboratory work is judged by the release print. A. Testing The proper processing of sound film, when introduced into the laboratories, necessitated an increase of personnel. The requirements of the sound engineers could be correctly interpreted and properly fulfilled only by those familiar with the theory of sensitometry. Some laboratories realized this fact, and either engaged additional help, or properly trained some of their own employees. Various types of sensitometers were installed, and sensitometric practice soon became a part of laboratory practice. The film manufacturing companies were particularly helpful in supplying and calibrating equipment and in training the personnel. After the practice of continually checking and maintaining developers and printers had been instituted, it became apparent that frequently variations were introduced by new emulsions. Checking new emulsions for speed and contrast then became an additional function of the new department. Various types of equipment were tried, with more or less moderate success. Photocell densitometers were developed for the rapid reading of sound track densities. In most instances, operators have returned to such standard equipment as a calibrated wedge or Nicol prism densitometers. Densities are usually read with the emulsion facing a diffused light. Sensitometric exposures are usually made in variable time steps with a high-intensity light. Unless otherwise stated, all reference made in this