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DO YOUR OWN DEVELOPING: 2
Step by easy step, here are the exact
solutions and procedures to be used in successful home processing . . . Part 2
HERBERT D. SHUMWAY, ACL
WITH the simple homemade equipment described last month in Part 1 of this article, movie developing at home becomes an easy-to-do reality. Before discussing the actual step-by-step procedure, let's first examine the theory behind the particular process used for developing home movies. It differs from the conventional negative-positive system used theatrically.
THE REVERSAL PROCESS
That particular process, known as the "reversal process," is so called because in developing home movie film we seemingly reverse a negative image into a positive image. What we actually do is to form a negative image first by developing the movie film in a specially compounded developer. Then, since we do not want a negative picture for projection, we next remove all the developed silver grains which form the negative by placing the film in a bleaching solution.
After removal of the film from the bleach, all that remains of the emulsion is the unexposed — and consequently undeveloped — silver bromide. This silver bromide, which is still light sensitive, varies in density according to the gradations of light and shadow in the subject photographed. If we now re-expose the film to any bright white light and then redevelop the film, a positive image of the original subject will result. Briefly stated, this forms
FIG. 9: Exact temperature of the developer, critically important in first run-through, is determined by thermometer.
the basic principle upon which the reversal process works.
THE SOLUTIONS USED With this outline of the reversal process fixed in your mind, let's turn now to a study of the five solutions required for reversal developing. Fortunately nearly all the necessary chemicals are available in ready-mixed, prepackaged form, so that all you need do is to dissolve each chemical in water according to the directions on its package. Moreover, all the solutions have excellent keeping qualities, so that they will need replacing only once in every two or three months unless, of course, they are
MOVIE DEVELOPMENT TIME-TEMPERATURE CHART
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DEVELOPMENT (MINUTES)
FIG. 10: Time of development in minutes is found by running across correct horizontal temperature line to point of its intersection by the diagonal.
FIG. 11: Winding stand speeds film loading on rack, an operation which must be done in dark.