Ninefold PrintA file that looks right on screen can still be wrong for press, and the gap between the two causes more delay than anything else in a print job. None of it is difficult once somebody tells you.
Bleed, and why a quarter inch matters
Trimming has tolerance. Sheets shift by small amounts as they are cut, so a design built exactly to finished size will show a white sliver on some copies where the blade landed a hair outside the artwork.
The fix is bleed: extend anything that runs off the edge past the trim line, conventionally by an eighth of an inch on each side. The extra gets cut away.
Its counterpart is the safe margin: keep anything important, particularly text, an eighth to a quarter inch inside the trim, so nothing critical gets clipped when the cut goes the other way. On signage the safe margin is much larger, because grommets and frame rails cross the edge.
Three numbers, then: bleed outside the trim, trim, and safe inside it.
Resolution is about final size, not pixels
Print wants roughly 300 pixels per inch at the size the image is printed. A 2000 pixel wide photograph is ample for a business card and thin for a poster.
Two things follow. Enlarging a small image does not add detail, so a logo pulled off a website will not improve by being scaled up. And a vector logo has no resolution at all: it is math, and it stays sharp at any size, which is why print people ask for one.
Large format is the exception. A billboard viewed from a distance is often produced well below 300ppi, because nobody stands close enough to tell.
CMYK, RGB and what happens in between
Screens emit light and mix red, green and blue. Presses lay ink and mix cyan, magenta, yellow and black. Some colors a screen can display, notably the bright saturated ones, simply do not exist in ink.
Files supplied in RGB get converted, and the conversion happens with or without you. Supplying CMYK means you have seen the converted version. Supplying RGB means the first time anyone sees it is on the proof.
Blacks are worth a specific note. Large solid areas set in 100% black alone can look washed out. A rich black, black plus some cyan, magenta and yellow, prints deeper. Small text should stay 100% black only, because rich black on fine type causes registration fringing.
Fonts, and the reason to outline or embed
If a font is not embedded in the file, the press cannot set the type, and whatever is substituted has different metrics. The layout reflows and nobody notices until it is printed.
Two safe approaches: export a PDF with fonts embedded, or convert type to outlines so it becomes artwork. Outlines cannot be edited or spellchecked afterwards, so it is best done at the end.
This is not theoretical. A file that silently drops to a fallback face is one of the most common reasons a job comes back looking subtly wrong.
Finishes need their own layers
Foil, embossing, debossing and spot gloss are not colors. Each wants a separate layer or a separate page in the file, drawn as solid black vector, showing exactly where the effect goes.
A note in an email saying "foil the logo" is how the wrong element gets foiled. More on how these work in foil stamping and specialty finishes.
Die lines
Anything cut to a shape needs a die line: a vector outline, on its own layer, marking cut and crease. Cut and crease are usually distinguished by color and marked as non printing.
Cartons and folders are designed around the die line rather than the other way around. Getting the structure drawn first, then designing into it, avoids the redraw that happens when a finished design meets a die that does not match. That order is the single most useful habit in carton work.
A short checklist
- Bleed added, and important content inside the safe margin
- Images at roughly 300ppi at final size
- Logos vector wherever possible
- CMYK, with any spot colors named and used consistently
- Fonts embedded or outlined
- Finishes on their own labelled layers
- Die line included, on its own layer, marked non printing
- Exported as a print ready PDF, not a screen or web preset
If artwork is not your job
Plenty of people managing print did not choose to and do not have a designer on hand. Saying "artwork is not ready" in a brief is useful information rather than an admission, and it changes what a shop quotes.
It is also a normal thing to hand over along with the rest. That is worth a conversation.