Carol Galbraith, the motion picture laboratory specialist in film inspection at the Library of Congress, took me on a tour through the film preparation area. This section of the Library of Congress complex is responsible for the inspection, cleaning and repair of film. Films are carefully inspected over light-boxes on work benches and any damage is noted and repaired. The repairs can vary from a single perforation replacement to a major repair of missing frame sections. The repaired film is then cleaned in an ultrasonic film cleaner and then goes to the timing/grading area.
The term timing and grading refers to the process of determining exposure values for film to be printed so as to produce a final result of good density.