International projectionist (Jan-Dec 1955)

roughened and nicked edges, torn perforation margins, and damaged splices. Curved diagonal abrasions are sometimes produced when the film is held manually against a reel flange during rewinding. Even-Tension Winding Necessary Rolls of film having convolutions with protruding edges are readily damaged when forced into shipping cases. The edges of the film may become bent or entirely broken, necessitating costly replacements. This is why exchanges prefer return of prints as they wind up in the projectors at the last showing. The lower sprocket of a projector insures smooth, even winding, provided that the take-up tension be properly adjusted. Many projectionists, nevertheless, dislike to use shipping reels in the lower magazines, but accidents seldom occur if the reel flanges are "spread" and the magazines are wide enough to accommodate such reels without scraping or binding. Film should wind up in the projectors with sufficient tightness to prevent undue sidewise movement of the film layers during shipment. Lateral abrasions usually result from movements of the film layers during shipment, abetted by the uneven transit of the film through the gate. THE ACE CUE MARKER The World's Best One push to left or right and all cues are finished. Marker made in 2 sizes for 16 or 35-mm for Standard, Tv, or CinemaScope. Price $29.50 SEE YOUR DEALER OR WRITE TO ACE ELECTRIC MFG. COMPANY 1458 Shakespeare Avenue New York -52, N. Y. UNITED COMMUNITY CAMPAIGNS Most commercial motor-driven rewinders have automatic shut-off switches to prevent violent slapping of the end of the film with damage to the leader. Many projectionists have devised excellent shut-off switches, some having seen more than 30 years of service with no signs of serious wear. Dimensional Deformations of Film Motion picture prints are subject to a number of dimensional defects. "Curl" is the most common dimensional deformation of film. Some degree of curl is present in all film and is seldom deleterious to projection quality. Curl is due to dimensional differences between the emulsion layer and its support, or film base, and is caused by changes in the moisture-content of the emulsion and solvent-content of the support. Air constantly changes in relative humidity and temperature and the emulsion absorbs and releases moisture in accordance with these atmospheric changes. A flat piece of film held close to an ordinary light bulb will immediately curl with the emulsion side of the film concave. This is caused by loss of moisture from the gelatine emulsion. The fact that the film base retains much of the curl imparted to it, even after all the emulsion has been removed, indicates that the structural strain of curl may become a more or less permanent characteristic of the film. Curl is said to be "normal", or positive, when the emulsion side is concave; negative when the emulsion side is convex. Most film curl is positive. It will be noted that positive curl is induced in a flat piece of film no matter which side is presented to the warmth of a light bulb. "Spoking" is the term applied to the wavy appearance of the convolu tions of a loosely-wound roll of film having either a high degree of curl or a permanent "twist." Edge-Weaving of Film "Twist" is a weaving of the film produced when the edges are longer than the center section, caused by loose winding of freshly processed rolls of film under adverse atmospheric conditions. When fresh film is wound loosely with the emulsion side "in", and stored under excessively dry atmospheric conditions, the undulations alternate from one edge to the other. If the film be wound emulsion-side out and stored under the same conditions, the undulations are directly opposite each other. When the edge-waves do not extend to the center of the film, but affect only one or both of the margins, twist is called "film-flute." Twist is usually s PUCES ^ not y HOLDING Film breaks are costly. Play safe by using JEFRONA All-purpose CEMENT Has greater adhesive qualities. Don't take our word for it. Send for FREE sample and judge for yourself. CAMERA EQUIPMENT CO. DEFT. J-7-8 1600 Broadway New York 19, N. Y. Clayton Ball -Bearing Even Tension Take-Ups For all Projectors and Sound Equipments ALl TAKE-UPS WIND FILM ON 2, 4 AND 5 INCH HUB REELS. SILENT CHAIN DRIVE THE CLAYTON REWINDER FOR PERFECT REWINDING ON 2000-FOOT REELS. CLAYTON PRODUCTS CO. WE GIVE INTERNATIONAL PROJECTIONIST • JULY 1955 31-45 Tibbett Avenue New York 63, N. Y. 29