International projectionist (Oct 1931-Sept 1933)

I FACTORS AFFECTING THE USEFUL LIFE OF CREENS ONE cubic inch of air contains 150,000 particles of dust. In cities a large part of the dust is coal and soot. The burning of one ton of coal releases 20 pounds of soot and dust containing sulphuric and hydrochloric acid. Dust and soot destroys everything it comeg in contact with. A sound screen is porous. The air goes through the screen, the dust and dirt stays on the surface. As time goes on the density of the dust accumulation is increased to a point where it becomes conspicuous as black streaks, smudges and discolorations. In the winter, the stage or platform is generally colder than the auditorium. The screen becomes chilled, resulting in a slight condensation of moisture on the surface. Although the condensation may not be perceptible to the eye or the touch, it is sufficient to cause the dust in the air to adhere to the screen. Dust forms a film on the surface of the screen, and each day this film gets thicker until it is a dark gray in color. As the dust gets thicker the projection light gets dimmer, the picture becomes dull and hazy, and it becomes increasingly difficult to get the picture in sharp focus. The! gradual loss of light brilliancy due to dust makes it necessary to gradually increase the amperage at the arc. This means shorter life to the carbons, and a greater current consumption. Dust also filters into the tiny sound holes, gradually closing up or at least reducing their size. This means a loss of sound volume in direct proportion to the extent to which the holes are clogged up. As the dust gradually clogs up the holes, it becomes necessary to increase the volume at the speakers. This causes added strain on the tubes and batteries, shortening their life. When more current is applied to the tubes in order to force the sound through the clogged up sound holes, overloading of the tubes is bound to occur, resulting in unnatural, distorted sound quality. Sound screens can be cleaned, but it is a process that requires skilled help to make it successful. The Walker Screen Corp. has said all there is to say in the following statement : "There is no satisfactory way of cleaning a screen despite many claims of manufacturers that screens can be washed. From the purely technical angle it is impossible to wash a screen. The fabric itself is washable and can be cleaned very easily, but it is almost humanly impossible to remove all of the dirt from so large an area as that of a motion picture screen, evenly and uniformly, without leaving streaks. Remove Dust Uniformly "The question of cleaning resolves itself down to the ability of an individual tb remove the dirt uniformly from a large area. The particular cleanser used has very little bearing upon the subject as a screen can be washed with equal results with any reliable soap dissolved in warm water, the solution applied with a sponge and the screen rinsed off with clean water. Good results apply only to small areas, however. "Every major circuit has devoted a great deal of time to cleaning of screens. Up to date the most satisfactory means found is to brush off the screen with a fine goat's hair brush at Hollywood and New York Papers Please Copy The Spio Commission, in which all branches of the German film industry and the German government are represented, has announced its firm decision to bring about an extensive cut of all star salaries and to bring down the wages for even the bearers of the bestknown names to a basis which is tolerable to the producer, the renter and the exhibitor. If the stars should turn a deaf ear to the appeal for a voluntary reduction, there is no doubt that their names and salaries they demand, which have been running up to 70-80,000 marks for a film of about four weeks' production, will be made public in the press. These stars, no matter how strong their drawing power, will find themselves excluded from forthcoming German productions. [19] least once a week from the time it is installed. In this way the surface can be kept fairly free of dust. In case a vacuum cleaner is available, excellent results can be obtained by reversing the action of the cleaner and blowing the dust and dirt off the screen from an angle." Rate of Discoloration While opinions vary as to the life of a sound screen, it has been definitely established that discoloration caused by age, dust and dirt reduces the reflection value an average of 10% every three months. This makes a total of 40% in a year. In cities and manufacturing centers the loss in reflection value is even greater. The importance of this loss can well be understood if it is considered that the average perforated screen has when new a reflection value averaging. 75%. Under extremely favorable conditions, this represents 10 F.C. (foot-candles) in each sq. ft. of the screen. A 40% loss in reflection value means reducing the screen illumination to 6 F.C. per sq. ft., or practically cutting the brilliancy of the picture in half. The projectionist and the house staff become so accustomed to the appearance of the screen that they do not realize the gradual loss of light that is taking place day after day. Loss of light on the screen begins as soon as it has been installed, and the loss continues to accrue as long as the screen is in use. Maximum Useful Life The conditions obtaining at the theatre with respect to the care given the screen, the dust in the house, chemical conditions of the atmosphere, etc., all control the useful life of the screen. It is safe to say, therefore, that the maximum useful life is from 18 months to two years, though it can be readily proven that the majority of theatres would save considerable money in current and carbon consumption if the screen were replaced at least once a year.