Definitions for "Colour key"
Proofs used to show entire flats of a job. Produced in layers of coloured acetate to match the process or spot colours, colour keys are tacked to the mounting paper on one edge only. This allows individual layers to be lifted for inspection. This kind of proof is not as colour-accurate as matchprints or cromalins. Also called colour proof.
Off-press transparent proofing system, specifically used for CMYK projects.
A printer's proof. It is four sheets of coloured acetate for examining the quality of process colour separations. This process is normally used when printing on a press capable of fewer than four colours at once. All AAs and corrections should have been made prior to seeing a colour key.
Keywords:  films, match, check, finished, range
A range of coloured films used as a standard by which to check the match and consistancy, during the run, of colours used to create the finished image.