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1952 Theatre Catalog, 10th Edition, Page 301 (265)

1952 Theatre Catalog, 10th Edition
1952 Theatre Catalog
1952 Theatre Catalog, 10th Edition, Page 301
Page 301

1952 Theatre Catalog, 10th Edition, Page 301

referred to as "idler cramping," can be especially harmful in the case of film which is somewhat brittle and when the bending is against the emulsion side, since long edge sections may be broken off completely. This particular type of mutilation has been known to occur repeatedly at the first pad roller following the intermittent loop. The trouble usually starts at an edge break or at a loosened corner of a splice. It might also result from careless threading. If no attention is given to this trouble, this bending may continue to the stiffened area of the following splice before the film properly reseats itself.

Safety Film

Numerous misleading reports have been circulated concerning the general performance of safety film. Many projectionists are under the impression that the present high acetyl type safety film now being manufactured is the same material which they may have encountered in the years past. As has been pointed out in an earlier section, present day safety material now replacing all nitrate film has properties which are fully suited to the requirements of commercial use. The projected screen image obtained from the new safety film is equivalent to that obtained from the former nitrate base materials. In many respects, the new safety material superior to the nitrate film formerly supplied. Splicing should not be any more difficult with the new film than with nitrate base materials if the following splicing suggestions are kept in mind. A splicing unit of some kind, however, is definitely recommended. Hand splicing, still popular with many projectionists, will not give dependable results.


Splicing has such a direct bearing on the life of film as to call for special and constant attention.

FIG. 29. Edge bending or creasing.


FIG. 30. Buckled splices caused by excessive scraping of film and too liberal application of cement.

Much film is ruined by poor splicing. Splices that are wide, stiff, buckled or out of line might cause the film to jump the sprockets so that torn perforations or breaks result. Perforations in the vicinity of :1 splice of this kind are always strained or broken. Buckled or bumpy splices such as illustrated in Figure 30 result from excessive scraping, which weakens the base, and too liberal application of cement. Excess cement not only distorts the weakened area when it has dried but squeezes out under pressure and attacks the base at either side of the splice, thereby increas ing the possibility of distortion. On the other hand, the applicator used'must be capable of carrying sufficient cement so as to completely cover the scraped area in one stroke.

While the full-hole join is standard in most exchanges, some automatic equipment is also in service which makes a curved between-perforation splice. The small bench-top splicer is the most widely used in both the film exchange and theatre. The pressure springs on this type of splicer should be kept free of hardened cement and scrapings and the springs should also be kept properly spaced so as to insure satisfactory contact across the full length and width of the splice. The scraping blade should be kept sharp in order that it will remove the binder coating beneath the emulsion, since this is necessary to obtain a good splice. Scraping blades are often kept in service long after they have become ineffective in their ability to remove the binder. During the scraping operation, contact with the metal bar will quickly dull the blade. It is necessary therefore, to change the position of the blade in the holder frequently or to replace it so as to have the best possible working edge. Safety razor blades are very efficient in their scraping action but they can easily score the base and are therefore not recommended.

Sandpaper or emery cloth, while admittedly very effective, should not be used for scraping, because the grit particles will be picked up by oily film and carried into the roll. Such particles not only cause serious surface abrasion but may also find their way into projector bearings. The fine wire brush (Figure 31) recently introduced for use with the bench-top spliCer has proved very helpful. This device may

be ordered through various supply houses. A few sweeping strokes of this brush, after scraping, will give the desired dull surface even though the blade has not been too effective. The proper. use of this brush is illustrated in a leafiet furnished by the manufacturer with each unit.

Satisfactory splices demand careful scraping, which means complete removal of the emulsion and binder coatings. On certain types of color films where these coatings are on both sides of the film, scraping of each of the surfaces to be joined is required. In any case, the surface on the back of the section to be joined should be thoroughly clean. If the back surface contains only a slight film of oil, some difiiculty may be encountered in obtaining successful splices. In many cases, this factor is overlooked and poor splices are falsely attributed

FIG. 31. Fine wire brush for bench-lop splicer available through supply houses.

to the particular cement usesthe splicing equipment, or to the film base itself. Sometimes, it is helpful to roughen the back surface slightly where certain films seem to resist satisfactory splicing. Another effective technique is to apply a very small amount of cement to the back surface and to wipe it off immediately. This acts as a primer coating preliminary to the actual splicing operation, and aids in obtaining thorough adhesion of the two surfaces to be joined.

The proper type of cement must be used and care should be taken to' avoid a great excess but sufficient to cover the entire area of the scraped surface. It is important to allow suflicientdhblding

1952 Theatre Catalog, 10th Edition, Page 301