A print file can open perfectly on your screen and still be unprintable. The five problems below account for most of the delays we see between “artwork sent” and “proof approved” — and all five are visible before the file leaves your desk.
1. No bleed, or a critical element inside it
Cutting is not exact to a tenth of a millimetre. The guillotine or the die lands within a tolerance, and the artwork has to extend past the trim line so that a small shift does not leave a white sliver at the edge. Three millimetres is the working standard.
The second half of this error is worse than the first: a logo or a line of text set within those three millimetres looks fine on screen and gets trimmed off. Text near the edge should be at least 3 mm inside the trim, not merely outside it.
2. RGB colour sent to a CMYK press
A press prints in four inks. A bright RGB orange has no direct equivalent — it will convert to something duller, and the conversion happens either in your file or in ours, silently, with a different result each time. Convert to CMYK yourself so you see what you are approving.
The related mistake: converting a Pantone reference to CMYK in the file. If a brand colour is specified as Pantone, keep it as a named spot colour. Converting it to CMYK and then asking for Pantone matching gives the printer nothing to match against.
3. Raster images at screen resolution
An image at 72 dpi is fine on a monitor and unacceptable on a box. At 300 dpi the same image is roughly one-sixth the physical size. There is no recovering detail that was never in the file — upsampling invents pixels rather than restoring them.
This arrives most often from logos pulled off a website, or a product photo saved from a social platform. If the only version available is low resolution, that is a fact to state early, not something to discover at proof stage.
4. Fonts not outlined
A font that is not embedded and not outlined gets substituted on the machine that opens the file. The substitute has different metrics, so line breaks move, a headline reflows onto two lines, and a layout that was checked is no longer the layout being printed.
Outline the text, or send the font files with a licence that permits it. Both work; neither is optional.
5. Structural and dieline errors
- Dieline on a printing layer. It should sit on its own layer, set as a spot colour, marked non-printing. Otherwise the cutter lines appear on the box.
- Artwork not placed on the actual dieline. Guessed margins on a template that does not match the real die produce a panel that runs onto a fold.
- Barcode rescaled to fit. A barcode has a specified magnification range. Shrinking one to make room in a layout is how a pack ends up failing at the scanner — the quiet zone around it also cannot be filled with graphics.
- Four-colour black for body text. Small text set as 100% K prints crisply; rich black on four plates misregisters and looks soft or fringed.
The check that takes five minutes
Export a PDF/X-4 at 300 dpi with 3 mm bleed, then reopen it and zoom to 200% on the smallest text and the barcode. If the text is an image rather than vector, or the barcode has graphics inside its quiet zone, you have found the problem before it cost a week.
The full checklist we apply on receipt is on the downloads page. Running it first usually removes one round trip from the schedule.