Proofing & Preflight

Every print job passes through a critical window between the designer's screen and the press sheet, and the tools that fill it — preflight, soft proofing, hard proofing, and press checks — exist to catch problems while they are still cheap to fix. Approving a proof without working through it is not a time-saver; it is a cost transfer from the printer to the buyer.

What Preflight Is

Preflight is the automated or manual inspection of a print-ready file before it reaches production — the name borrows from aviation's pre-takeoff walkaround. A standard check looks for missing or unembedded fonts, images below the resolution threshold (typically 300 ppi at final size), color-mode mismatches (RGB in a CMYK document, or spot colors that should be process), insufficient bleed, incorrect trim size, missing or wrong-scale die lines, and overprint settings that could make objects disappear or knock out unexpectedly. It also flags transparency-flattening issues and ink coverage beyond press limits. Behind the scenes the file is interpreted by a raster image processor, described at https://en.wikipedia.org/wiki/Raster_image_processor, which turns the page into the data the output device actually images. Most professional workflows run preflight automatically; designers can and should run the same checks first, because finding a missing font on your own machine costs nothing.

Why It Saves Money

Problems found in preflight are corrected with a file revision. Problems found after press is running are corrected with reprints, buybacks, or negotiated settlements — and the cost gap can be enormous on long runs or specialty substrates. Preflight is not a guarantee the file looks as intended; it confirms the file is structurally sound for output. Color appearance, layout judgment, and content accuracy require proofing.

Soft Proofing

A soft proof is an on-screen preview through a color-managed workflow — a calibrated PDF preview or a color-management application on a profiled monitor. It is fast and costs nothing once set up, and it is genuinely useful for reviewing layout, image placement, body copy, page order, and obvious color errors. Its limitation is physical: a monitor emits light while a sheet reflects it, so even a calibrated display cannot fully simulate ink on an uncoated sheet, a metallic ink, or a near-neutral gray. For color-critical work, a physical proof is the responsible standard.

Hard Proofing and Contract Proofing

A hard proof is a physical print on a calibrated device — typically a high-quality inkjet proofer running color management with an ICC profile matched to the intended press and stock. A contract proof is a hard proof made to a documented, verified standard, carrying a certification strip confirming the device was within tolerance. The contract proof is the reliable reference for color-critical work: once approved, both parties share a physical object that defines an acceptable press sheet, and operators set ink densities to match it. Short-run digital, where the output is essentially the proof, may not need one; high-value offset — packaging, annual reports, catalogs — almost always does.

What to Check on a Proof

Work through a proof in sequence, not at a glance. Check copy and spelling first — the eye skips familiar text when color and images compete for attention. Then image quality: sharp at print size, believable color, no banding or compression artifacts. Review color against references — brand standards, prior approved samples, or the contract proof. Confirm trim position and that critical content clears the safety zone. Check bleed on all four sides. If the job folds, die-cuts, or scores, verify those lines fall where they should. Finally, confirm page sequence, especially on multi-page jobs where signatures can reorder in imposition.

The Press Check

A press check is an on-site visit while the job runs: the buyer reviews pull sheets as the operator brings the job up to color and confirms the sheet matches the contract proof. It is standard for brand-sensitive, high-volume, or high-value offset work where a reprint would be costly, and not typically feasible for digital short runs.

Sign-Off and Responsibility

Approving a proof — signing a sheet or clicking approval online — transfers responsibility for the job's appearance from printer to buyer. After sign-off, if the press sheet matches the approved proof, the printer has met their obligation. Review carefully, involve the right stakeholders, and do not approve under time pressure. Before signing, work through: read all copy and headlines; verify proper nouns, phone numbers, URLs, and addresses; check every image for sharpness, cast, and placement; confirm brand colors; measure bleed on all edges; verify trim size; check fold and die lines; confirm page count and sequence; and submit any changes as a single consolidated round.