We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
THE LUBRICATION OF MOTION PICTURE FILM
By J. I. Crabtkee and C. E. Ives*
WHEN freshly developed or so-called "green" motion picture film is passed through a projector, there is a tendency for an incrustation to accumulate on the aperture plate or tension springs which retards the free passage of the film through the machine. Chemical analysis has shown that this incrustation consists largely of gelatin with more or less silver, dirt, and oil, but it contains usually only a trace of the metal or alloy of which the gate is composed.
The effect of the incrustation is to increase the friction between the metal parts of the gate and the gelatin coated surface of the film. This causes excessive strains on the edges of the perforations at the pull-down sprocket which ultimately results in torn perforations and therefore a diminished projection life of the film.
It is possible to reduce considerably the tendency for the formation of the gate incrustation by suitable lubrication of the film surface. This is accomplished usually by the application to the edge of the film of a thin line of paraffin wax which melts under the heat of the projector and forms an effective lubricant. However, the wax tends to wander over the picture area if applied in excess, and particularly in the case of sound record films this is very objectionable.
It is the object of this paper to discuss the various methods of lubrication employed to date and to indicate a new method which is equally satisfactory for sound record and ordinary motion picture films.
Factors Affecting the Ease of Passage of Motion Picture Film through
a Projector
The facility with which the film passes under the pressure springs in the projector gate depends on:
1. The physical condition of the gelatin coating of the film.
2. The conditions to which the film is subjected in the projector.
1. If motion picture film is examined under a microscope by reflected light, it is seen that the gelatin surface, even in the region which is relatively free from silver, is covered with innumerable extrusions (see Fig. 1, magnification 540). The roughness of the
* Communication No. 330 from the Kodak Research Laboratories.
522