The art of sound pictures (1930)

2 56 THE ART OF SOUND PICTURES veloped, and, at the present time, both films are printed on opposite sides of a double-coated film. We now have a single film with a latent blue-green picture on one side and a latent red-orange picture exactly opposite it on the other side of the film. These pictures are now treated with chemicals in such a way that the pictures on one side of the film turn red-orange, and the pictures on the other side of the film turn blue-green. This is a chemical conversion process, in contrast to the dye process used by Technicolor. In the chemical conversion process, the actual chemicals which make the picture record on the film are converted into other colored chemicals, leaving the picture on the film in the actual color desired. When the prints are finished, they constitute what is called a double-coated film, that is, a film with color picture records on both sides. In the early days of this double-coated film technique, many practical objections to its use arose. The chief objections were based upon the fact that the double-coated film scratched, cracked, and wore out quickly when run through an ordinary projector designed for film with a picture image on one side only. Technicians, however, have developed a special type of shellac which protects this film, so that these practical difficulties are largely overcome. Multicolor has recently announced, however, that they have perfected a single-coated film process which they are about to put on the market. One of the chief advantages in the use of the conversion process in printing the colored object on film is the fact that chemical conversion proceeds definitely to completion and therefore does not vary from print to