Separation methods from coloured originals - three-colour subtractive films.

In the Colour Duplication chapter the procedure for making separation positives from colour negatives is described, and the procedure is similar when making separation negatives from positives. The same sensitometric control calculations apply. The technique can be adapted to a wide range of restorations provided the original characters of the colour process are known.

The usual reason for making any separation during a restoration process is in order to correct for fading. If fading has not occurred or a copy of a film image is required in its present condition separations are an unnecessary process.

Separations are still however considered the best method of preserving a coloured image, because the black and white image has a longer life than any colour image. However, most laboratories, when asked to reconstruct a positive film image from archive stored separation negatives or positives find that the quality of their production was not very high. Contrast often does not match, registration is not good and storage sometimes results in separations having different shrinkages.