The ingredients must be mixed in the order indicated. All the chemicals are readily and cheaply obtainable at any photographic chemists and drug stores. After preparation the developer will keep for a long period so long as the bottle is well stoppered and kept in a cool place. Only the highest grade chemicals of a reputable brand should be used. A slight saving in the purchase of these essentials is false economy, because a film costing one hundred or more times the money saved in the outlay upon chemicals may thus be ruined.
In cases of over-exposure, perhaps the most common fault of the beginner who does not understand the stopping down of the lens, a restrainer is necessary. This is composed of the following:—
| Avoirdupois. | Metric. | |
| Potassium bromide | 1 oz. | 30 grammes |
| Water | 10 oz. | 300 cubic centimetres |
The process of development is as follows. First, the film is transferred from the dark film-box of the camera to the frame. The latter, if it is of the wooden type, can be spun round freely when mounted on its stand. It is not advisable for the beginner to withdraw the coil of film bodily from the box until he is expert in winding the frame, otherwise, to his surprise and disgust, the spool may fall out and the film be precipitated to the floor in an inextricable tangle. He should let it remain in the dark box until it is removed by being drawn slowly through the velvet-lined slot. The free end of the film should be fixed with a drawing pin to one end-bar of the frame, and contained between two guide pins, with the emulsion side outermost. The emulsion side can be recognized even in the subdued light of the dark room because it has a matt surface, while the other side is glossy. The difference between the two sides can also be detected by the touch. When the end of the film has been attached to one end-bar the frame is turned, the film meanwhile being permitted to slide out of the dark box, until the opposite end of the frame comes up. The film is passed over this bar, also between the first pair of guide pins, and once more, with a half-turn to the frame, the film passes along the second side of the frame back to the first bar, between the succeeding pair of guide pins, over the top and back again to the opposite bar, this process being continued until the coil of film is unrolled, when the second extremity is likewise fixed to the bar by means of a drawing pin. The film while being wound must not be drawn too tightly; at the same time it must not be too slack. When winding has been completed, the frame and film will have the appearance shown in the illustration facing p. 65. The guide pins in the end-bars prevent the edges from overlapping or touching. The result is the presentation of two emulsion faces on either side of the frame and each face resembles the sensitized side of a dry plate.
The Film transferred from the Developing Frame to the Drying Drum.
For amateur use a small drum can be used.
By permission of Williamson Kine. Co., Ltd.
The Film Wound on Frame and placed in The Developing Tray.