Dye-transfer process

Relief printing (short relief) is in the photograph is a collective term for those precious printing process, with the help of gelatin reliefs produced on the one hand and on the other hand they are used for photomechanical copies in the form of motion picture films, paper prints or slides.

There are two groups of relief method: wash- reliefs and source - reliefs.

Pressure principle

The printing principle is with the gelatin on a Matrizenfilm or a matrix ( light- sensitive coated glass plate ) correspondingly receiving the proper ink and let this vacuum of the gelatin film on a target or a target plate. Historically, the technique is based on the Ölumdruck.

The various relief procedures had until the introduction of photographic color films of acceptable quality in 1935 ( Kodachrome, Agfa Color - New) great economic importance because they could be used to produce colored paper prints and slides. Some methods retained their significance beyond this turn, because they have advantages for specific applications, such as the Großdia projection or to the presence of artistic interest.

Wash- reliefs

They use the property of some photochemical developers to harden the gelatin silver halide emulsion to varying degrees according to their respective exposure. The unhardened gelatin can be washed subsequently with a solvent, water-based at a certain temperature; remaining on the die, gelatin is used to capture the ink.

The group of wash- relief methods include, for example, the Uvatypie and Technicolor 4

Although the concept of dye-transfer ( dye transfer ) can be used in substance for both relief process, but is with him because of the 20th century for decades and widely established practice generally one or the other form of wash-off relief meant. The prints produced in this way are called dye-transfer prints.

Source - reliefs

In contrast to the washout reliefs Matrizenfilme and plates are held with silver salts with chromium salts, usually potassium or ammonium bichromate sensitized with source reliefs. During development, the gelatin swells to different degrees according to their exposure and then displays a proportionally longer exposure or less pronounced ability to take on color, which is then in turn extracted by the gelatin of the film target or the target disk. Similar techniques are the light pressure and the photogravure.

The group of source - relief methods include, for example, the Pinatypie and Erwinotypie.