Murder on the Screen 1958 Eastman Kodak; Preventing Film Damage

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A detective tracks down the murderers of motion picture film.

Originally a public domain film, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/Film_stock

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

Film stock is an analog medium that is used for recording motion pictures or animation. It is a strip or sheet of transparent plastic film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determine the sensitivity, contrast and resolution of the film. The emulsion will gradually darken if left exposed to light, but the process is too slow and incomplete to be of any practical use. Instead, a very short exposure to the image formed by a camera lens is used to produce only a very slight chemical change, proportional to the amount of light absorbed by each crystal. This creates an invisible latent image in the emulsion, which can be chemically developed into a visible photograph. In addition to visible light, all films are sensitive to X-rays and high-energy particles. Most are at least slightly sensitive to invisible ultraviolet (UV) light. Some special-purpose films are sensitive into the infrared (IR) region of the spectrum.

In black-and-white photographic film there is usually one layer of silver salts. When the exposed grains are developed, the silver salts are converted to metallic silver, which blocks light and appears as the black part of the film negative. Color film has at least three sensitive layers. Dyes, which adsorb to the surface of the silver salts, make the crystals sensitive to different colors. Typically the blue-sensitive layer is on top, followed by the green and red layers. During development, the exposed silver salts are converted to metallic silver, just as with black-and-white film. But in a color film, the by-products of the development reaction simultaneously combine with chemicals known as color couplers that are included either in the film itself or in the developer solution to form colored dyes. Because the by-products are created in direct proportion to the amount of exposure and development, the dye clouds formed are also in proportion to the exposure and development. Following development, the silver is converted back to silver salts in the bleach step. It is removed from the film in the fix step. Fixing leaves behind only the formed color dyes, which combine to make up the colored visible image. Later color films, like Kodacolor II, have as many as 12 emulsion layers,[citation needed] with upwards of 20 different chemicals in each layer...

Deterioration

All plastic is subject to deterioration through physical or chemical means, and thus, motion picture film is subject to the same deterioration. Films deteriorate over time, which can damage individual frames or even lead to the entire film being destroyed... In the final stages of celluloid decomposition, the film turns into a rust-like powder. Likewise, tri-acetate stock is also vulnerable to deterioration. Because of the small gauge of the film, owners of home-made films often find that their film can become shrunken and brittle to the point where the film is unwatchable in the space of a few years. In general, decaying acetate film breaks down into acetic acid, and similar to celluloid decomposition, leads to an auto-catylictic breakdown of the base that cannot be reversed. The result of the acetic acid released is a strong odor of vinegar, which is why the decay process in the archival community is known as "vinegar syndrome". Modern polyester-based stocks are far more stable by comparison and are rated to last hundreds of years if stored properly...

The distinction between camera stocks and print stocks involves a difference in the recording process...

Due to the specialized nature of the exposure and the higher degree of control afforded by the film lab equipment, these intermediate and release stocks are specially designed solely for these applications and are generally not feasible for camera shooting. Because intermediates only function to maintain the image information accurately across duplication, each manufacturer tends to only produce one or two different intermediate stocks. Similarly, release print stocks usually are available only in two varieties: a "normal" print or a deluxe print (on more-costly print film like Kodak Vision Premiere) with slightly greater saturation and contrast...