High Temperature Processing

The high-temperature processing is possible to all materials should preferably be processed at the temperature recommended by the manufacturer. Where ambient temperatures are high, processing should be delayed until the cooler evening or night hours or ice packs or other methods of cooling should be employed. When none of these methods is practicable high temperature processing is the only alternative. The twin dangers of high-temperature processing are chemical fog and damage to the emulsion from excessive swelling. They can be combated to some extent by restricting the alkalinity of the developer and adding sodium sulphate to reduce the swelling tendency. At temperatures up to 35°C, normal developers such as D76 can be adapted to high-temperature processing simply by the addition of a specified quantity of sodium sulphate. The Silver less monochrome images on conventional monochrome film is composed of minute grains of metallic silver suspended in a gelatin compound. It has been a satisfactory method of producing high quality images almost since photography began, but it does have its disadvantages. The function of the metallic grains is to stop light passing through certain image parts. This color film technology has now been extended to monochrome film and the 1980s will see the rapid introduction of totally new types of film such as Il ford’s XP1400 and Agfa’s Agfa pan Vario-XL Professional. Development time is the same, whatever the speed rating. Il ford’s recommended basic speed for XPI 400 is ISO 400/27°, with push processing possible for ISO 800/30° and 1600/33°.