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OIL SPOTS ON MOTION PICTURE FILM
G. E. Matthews and J. I. Crabtree*
MOTION picture film may become spotted with mineral oil in one or more of the following ways: (1) in the camera during exposure; (2) during passage of the film through a printer or processing machine ; (3) when squeegeeing with a pneumatic squeegee previous to drying; and (4) during drying with compressed air containing atomized oil. If the film becomes spotted with oil previous to processing, the oil acts as a resist and causes uneven development. If the oil has access to the film during drying, the drying of the gelatin is locally retarded and spots similar to moisture markings are produced.^
Oil spots are also usually present on film after projection, but the nature of these spots is too well known to require elaboration.
The literature contains practically no information relative to spots caused by oil on the surface of film or plate emulsions, although Russell has shown that vapors from mineral oils do not produce any deleterious effects. ^
This investigation was undertaken in order to determine the precise nature of the spots produced by mineral oil on various motion picture film emulsions previous to or during processing, to classify typical markings, and to find means for their prevention.
Effect of Oil on Unprocessed Film
The effects of the following factors were studied: (1) the nature of the film emulsion ; (2) the nature of the oil ; (3) method of application of the oil; (4) order of application of the oil in relation to the exposure; (5) the time elapsing between application of the oil and processing of the film; (6) manipulative treatment of the film after application of the oil; (7) miscellaneous factors such as the quantity of oil applied, the nature of the developer, the method of removal of the excess water before drying, and the time and temperature of drying.
* Communication No. 325 from the Kodak Research Laboratories.
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