Most jobs that stall in prepress stall for one of seven reasons. None
of them are hard to avoid, and all of them are cheaper to fix in your file than on a
plate.
Not sure it is right? Send it anyway and say so. Prepress would rather
look at a file before it is plated than after.
FormatSend a press-ready PDF. Export to PDF/X‑1a or PDF/X‑4 if your software offers it. Those presets exist precisely to stop the things that go wrong: they force fonts to embed, flatten or preserve transparency predictably, and carry the trim and bleed boxes with the file. A PDF is also the only format that looks the same on our screen as it did on yours.
FontsEmbed or outline the fonts. A font that is not embedded gets substituted, and substituted type re-flows — lines break in new places and a two-line heading becomes three. Embedding keeps the type you set. Outlining converts it to artwork, which is safe but no longer editable, so outline last and keep your working file.
ImagesImages at 300 ppi at final size. The resolution that matters is the resolution at the size the image is printed, not the number in the file. A 300 ppi photo scaled to 200% is a 150 ppi photo. Web images are usually 72 ppi and will not hold up on paper, however good they look on a screen. Line art and logos are better supplied as vector, where resolution stops mattering at all.
ColorCMYK, not RGB. A screen makes color with light and a press makes it with four inks — cyan, magenta, yellow and black. Convert to CMYK yourself and you decide what happens to the bright blues and greens a press cannot reach. Leave it in RGB and the conversion happens without you. If a specific brand color has to be exact, ask about a spot ink instead: it is mixed to a number rather than built from four screens.
Bleed1/8 inch of bleed where art runs off the edge. Bleed is artwork extended past the trim line — 0.125 in on every edge the ink runs off. Sheets are trimmed in stacks and the knife moves a hair through the lift, so without bleed a white sliver shows on some copies and not others. Extending the background is the whole fix.
TrimKeep live matter clear of the trim. The same knife movement works inwards. Keep type, logos, page numbers and anything else that must not be clipped at least 1/8 inch inside the trim — more on a thick saddle-stitched booklet, where the inner pages creep outwards as the spine gets fatter and get trimmed harder.
NamingName the file so a human can read it. acme-spring-catalog-v3-2026-04-12.pdf tells us what it is and which version it is. final_FINAL2.pdf tells us nothing, and two of them in one folder is how the wrong version gets printed. Supply multi-page work as single pages in reading order rather than as reader spreads — imposition is our job, and pages pre-paired into spreads have to be taken apart again.
Then look at the proof. Proofs come back as an emailed PDF or as a hard
copy. Read the spelling, the phone numbers, the web addresses, the page order and
the folds. A PDF on an uncalibrated monitor will not tell you the truth about color
— ask for a hard copy when the color is the thing that matters.
More on how files become plates on the prepress page.