Made in 1948 by the De Frenes Company, this U.S. Navy training movie breaks down the steps that must be taken for proper film processing and shows each of the chemicals used and what they do. It opens with a photographer using a Speed Graphic type camera, checking his exposed film for satisfaction after taking a picture (:43). A diagram then points to the image which was thrown by the camera lens that has left an invisible record of itself on the film (:51). This record cannot be used until it is made permanent and visible through the processing procedure. It is too sensitive to light and would be ruined if any light touched it (1:05). The sensitivity of light has to be cancelled out (1:14). A combination of chemicals removes this sensitivity and the film will demonstrate this process in step by step form (1:26). The image on the film is shown as a jet (1:38) and a cartoon demonstration follows of the silver salt particle’s activating to form the latent image (1:46). The first step of the process is to use a chemical to blacken the latent image (1:56). The chemical used is known as a reducer (2:03). Types of reducers include metol, hydroquinone, and pyro (2:08). The reducer is added to water (2:18) though once the negative is thrown in, it does not work as the solution is without alkaline (2:32). An accelerator of sodium carbonate is added (2:46). When both the reducer and the accelerator are combined the process still does not work (3:14) as it is too active and the reducer ends up working on unexposed silver particles. The action must then be restrained (3:19) and protection is needed for the silver salt particles. A restrainer of potassium bromide is added (3:24) which prevents the reducer from darkening the entire film while allowing the latent image to develop (3:32). When all three chemicals are added (3:42) the negative is still not developed properly (4:01) and now it is because of the oxygen in the water that quickly burns everything up. Sodium sulfite works as a preservative protecting the chemicals in the process (4:24). Now when all of the chemicals are added, the latent image is developed properly and this solution could be used multiple times (4:45). From here, the film is transferred to the short stop bath (5:08) which immediately halts all developing actions (5:08). Acetic acid is the active ingredient in the short stop bath (5:11). The film is still sensitive to light however, (5:26) and the underdeveloped silver salt particles must be removed in a fixing bath (5:46). This bath is made up on sodium thiosulfate that eats away at the underdeveloped silver salt particles (5:52). The film is sufficiently insensitive to light now, but the active fixing agent must be rinsed out (6:21) so it does not cause the image to fade. Water is enough for rinsing, though too much can cause the silver particles to clump (6:42) and this results in an image without fine details. After the rinse, the film must be dried on both sides (6:53) and hung out to dry. If it is dried too slowly, the silver particles again tend to clump up and quick drying methods without any direct contact with heat are necessary (7:02). The film begins to wrap up with the information that each step must be precise and it helps to know what each chemical in the steps do (7:48). It was presented by the US Navy Department (7:31).

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This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD and 2k. For more information visit http://www.PeriscopeFilm.com