Autochromes Lumière



In order to produce a positive image, the exposed plate was submitted to a "reversal" development process (comparable to contemporary slide treatments). The formulas and prescriptions for this were contained in detailed manuals published by the Lumière factories and the Lumière annual report would take regular account of all the operational modifications in the treatment of the plates. Operators might also sometimes experiment with variants of the official recommendations, which were often the origin of animated exchanges at meetings and shared with other practitioners in specialised journals.

This treatment, which was hardly more complicated than that of an ordinary photographic plate, allowed the operators to develop their Autochromes near to where they took their pictures. This helped to assure good results, especially for those who had adjustments to make concerning the exposure. The only materials necessary for this operation were some basins and bottles that could be easily transported in a suitably arranged trunk. Outside the usual variables of photographic development (duration, temperature, agitation), the two major constraints of Autochrome development were that the solutions had to be kept relatively cool (15° to 18°C), so not to weaken the thin layer of emulsion, and that handling the wet plate had to be done with particular care, so to be sure not to damage the surface.

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