The handbook of motion picture photography (1927)

i II E HANDBOOK 0 F M OTION cates that the solution is too strong. Rinse the film and place it in this solution. The pink color will turn to muddy brown. Rinse the film and place in fresh, weak permanganate. With each change of solution the time required for the color change will increase. The solution will be turned to straw yellow instead of brown after a time. Continue alternating water and weak permanganate until the watery permanganate remains pink for two minutes after the film is immersed in it. With each change make the permanganate slightly weaker until at the last it is but of a slight pinkish tinge. When this color persists for two minutes, practically all hypo has been removed. The film is now rinsed in five changes of water and dried. With this method it is quite possible to thoroughly wash the film in five minutes. When the film has been washed, it is placed upon the drying rack. The film is wound directly from the developing rack to the drying rack or drum. When the film is all upon the dry rack, the rack is slowly rotated until the film is dry. This gives a uniform density throughout the film. The rack or drum may be turned by connecting a suitable electric motor to it. The pulleys used should be of such size that the rack turns not less than thirty nor more than one hundred and fifty times per minute. One revolution per second is a good speed for small racks and drums. When the film is dry, it should be polished. It is inevitable that some water marks will be left upon the celluloid side of the film. A pad of absorbent cotton or even better, of chamois skin, is thoroughly wet with alcohol. It should not drip, but should be quite damp. This is passed beneath 156