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Gasparcolor OR Gaspar Color

Description

Gasparcolor was the first three-color multi-layer monopack film available for practical use. It was a double-coated print film with a cyan layer on one side and two layers dyed magenta and yellow on the other side (see illustrations). As a consequence of this arrangement the process required b/w separation records of the red, blue and green light, either produced by a beam-splitter camera or by successive photographs taken through the corresponding filters. Thus most of the films produced with Gasparcolor were animation films. Gaspar’s process was chemically and optically very sophisticated and elegant. It produced brilliant and very stable colors.

The basic idea of the silver dye-bleach process was the controlled destruction of dyes in relation to the amount of developed silver present at a specific locus. Therefore the gelatin emulsions were dyed before exposure. After development the dyes were bleached by acid thiourea with the silver serving as a local catalyst for the reaction. Since the dyes are destroyed in the exposed areas Gasparcolor is a reversal process.

Although the chromolytic principle was proposed very early, many obstacles had to be resolved for a practical solution. For instance, as Gaspar pointed out, for optical reasons it was not possible to sensitize the layers to the complementary spectrum of the dyes. Therefore Gaspar chose an arbitrary connection between the colored light for exposure and the corresponding dyes such that the green separation was exposed by blue filtered light on the magenta dyed layer and subsequently the blue separation by the use of red filtered light on the yellow layer. The cyan dyed emulsion on the opposite side of the film was exposed by blue filtered light through the red separation print (see illustrations). The yellow layer acted as a filter to block out the blue light from both sides.

For political reasons Gaspar had to flee from Germany before the Second World War. While he established a plant in London, he could not convince the producers in the US to adopt his process. In the late 1950s, however, the principle was revived by Ciba-Geigy and distributed as Cibachrome (later Ilfochrome) for photographic paper prints.

Gasparcolor prints can be identified by the emulsion layers on both sides of the film. In case of scratches or cuts the colors of the layers become visible (see illustration). In addition, the sound track is often printed in color.











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