Light Fastness Evaluation of Colour Photographs

Abstract

AbstractThe light fastness on the British Standard (B.S.) scale of a variety of examples of colour photographs, both transparencies and prints, has been determined and the possible lifetimes under normal conditions, before fading is noticeable, have been estimated.In transparencies from reversal films there appears to be a correlation between emulsion speed and speed of fading: the slowest film gives the best fastness, its colours are graded about 4 (on the B.S. scale of J to 8) in medium shade depths. This is probably adequate for occasional projection, though poor by textile standards, corresponding with a possible useful life of about 4 hours under continuous exposure in a modern projector. The fastest reversal films (l00 ASA and above) are very poor indeed and are graded about J on the scale, corresponding with a possible useful life of only about 0.5 hours in a projector.Colour-developed paper prints are graded between J and 2, and estimated to have a useful life of between 4 and 12 months under cont...