f a person has never visited a motion picture laboratory and been given a comprehensive tour of its operations, what happens to his film at the lab takes on an air of mystery, and, in the minds of some, even a kind of black magic. Although it is sometimes flattering to have a customer say "my lab can do anything", it is much better for all concerned when a filmmaker takes the time to learn about the laboratory and to find out exactly what it can do before she sends in her film. We hope that this will be one step toward solving "the mysteries" of laboratory practices.