Identifying the colour system.

There have been a great many colour film systems since 1900 and such is the variety of techniques used, their restoration cannot be carried out by a single coherent duplication technique. Successful restoration usually requires identification of the original colour process as the first step, but there are, undoubtedly, many pieces of film in archives that have not been identified, and many specialists believe that just as many are incorrectly identified.

A major problem is that the literature on colour film systems is now generally in patents, which requires time, great patience and application to both locate and interpret. Some systems were never completely patented and many systems changed with time, sometimes quite abruptly, without good records. Some systems were used for just a single film production before being lost or altered, and in the case of Technicolor in the early 1930's the technology changed repeatedly from film to film but the name of the process stayed the same, as it was the name of the operating company!

Edge data is sometimes of great value in identifying the system, but although much data can be acquired from the edge of a film it is not easy to refer this back to a system. Many archives have extensive knowledge of systems local to them but find it difficult to identify unfamiliar film. No doubt, an eventual sharing of information will overcome this problem.

Restoring archive colour film by photographic duplication is not a single procedure that can be described and defined. The number of different processes and procedures used in old colour systems is considerable and each requires a different restoration process. The element available in the archive may be a black and white intermediate or a colour intermediate consisting of dyes, and each will require a different route.