proof

A proof is a trial impression pulled from type, plates, or digital files before committing to a full production run. It shows how the final printed piece will actually look, catching errors in text, color, registration, and layout that exist only in physical form, not on screen. For letterpress and offset work, proofs are essential because corrections made at this stage cost minutes and small money; corrections discovered mid-run cost hours and real money.

The printing trades recognize several proof stages. A galley proof shows text alone, typically on a long strip, used by editors and typesetters to catch typos and spacing issues before page assembly. A page proof or composite proof shows the finished layout with images and text in position. In offset and digital printing, color proofs (contract proofs, press proofs) simulate the final color output, allowing approval before the press runs thousands of sheets. Larger printers may pull bluelines or Matchprints specifically for color checking.

Proofs are pulled using the same materials and methods as production runs, scaled to the job at hand. A single sheet from a platesetter, or a short run of 10 to 50 copies, is far cheaper than discovering registration misalignment, dot gain surprises, or ink color drift after 100,000 impressions. The proof is approved by the client or in-house quality team, marked up with corrections, and returned to the production floor before the official press start.

The term proof carries historical weight. In the era of hot metal and photographic plates, a proof was a physical object: ink on paper, impossible to fake or argue about. The shop kept a file proof in the job jacket as a legal record of what was approved. Even in today's digital workflows, many shops still pull a press proof from the production press itself, running at reduced speed on the actual paper stock, because nothing compares to seeing the inks and the substrate interact under real conditions.

Common failure modes: proofs approved too quickly without close inspection; proofs pulled on different paper than the final job, masking substrate-dependent color shifts; proofs that do not reflect the correct screen ruling or halftone angle; proofs signed off by the wrong person or without written sign-off at all. Disputes over whether a finished job matches an old proof are common in contract work; this is why proofs are filed and dated.