Preparing artwork for print — bleed, safe area, colour and resolution

Most delays in a print job are not caused by the press. They are caused by a file that has to go back to whoever made it, and the reasons repeat: no bleed, text too close to the trim, the wrong colour mode, images at screen resolution, fonts that did not travel with the file.

None of this is difficult. It is just specific, and it is easier to get right before the file is sent than after it has been rejected.

Bleed: background past the edge of the page

Paper is printed on a larger sheet and then cut down. Cutting is mechanically accurate, not perfect, and a stack of sheets shifts slightly as the blade goes through. If your background stops exactly where the cut should be, some copies in the run will show a thin white line along one edge.

Bleed is the fix: extend every background colour, image or panel past the trim line so the blade always cuts through ink.

• Small commercial print — visiting cards, flyers, brochures, letterheads — conventionally takes 3 mm of bleed on every side.
• Large format and outdoor takes considerably more, and how much depends on how the piece is finished. A banner with a welded pocket or a stretched frame needs enough material to wrap. Ask for the figure for your specific job.

A design with a plain white background technically needs no bleed, because white paper cut slightly off still gives white. Everything else does.

Safe area: keeping content away from the edge

The other side of the same tolerance. If bleed protects the background, safe area protects the content.

Keep text, logos and anything that must not be clipped at least 3–5 mm inside the trim line on small print, and considerably more on anything that is folded, bound, drilled or fixed into a frame.

Three cases that need more room than people expect:

• Bound documents. A perfect-bound or saddle-stitched booklet loses part of the inner margin into the spine. The thicker the book, the more it loses.
• Folded pieces. On a roll-fold leaflet the panels are not equal widths — the panel that folds innermost is deliberately narrower. A design drawn as three equal thirds will not fold correctly.
• Anything with a hole in it. Eyelets, drilled tags and hanging holes all need clear space around them.

Colour: RGB, CMYK and the colours that cannot be printed

Screens make colour by emitting red, green and blue light. Presses make colour by laying down cyan, magenta, yellow and black ink, which absorbs light. The two ranges overlap, but they are not the same, and the screen's is larger.

That means some colours you can see on your monitor cannot be printed at all. The usual casualties are bright saturated blues, vivid oranges, and anything neon or fluorescent. They do not fail dramatically; they come back slightly duller and slightly shifted, which is more annoying than an obvious error.

What to do about it:

• Supply artwork in CMYK for anything printed by a normal process, so the conversion happens under your control rather than silently at the press.
• If a colour must be exact, identify it by a spot colour reference rather than describing it. A brand blue is a reference, not "the blue in the logo".
• Black text should be plain black, not a mix of all four inks. Four-colour black on small type produces fuzzy edges wherever the plates are a hair out of register. A large solid black panel is the opposite case and often does want a richer mix — worth asking about rather than assuming.
• Do not judge colour on an office printer or a phone screen. Neither is calibrated, and both will mislead you in different directions.

Resolution: pixels at the finished size

Resolution only means something in combination with a physical size. A 2000-pixel-wide image is generous on a visiting card and hopeless on a banner.

The convention for paper printing is 300 dpi at the final printed size. Large format is read from further away, so it tolerates much less — often 100–150 dpi at size, and sometimes less again for a hoarding read from a road. The principle is the same: work out the finished dimensions first, then check whether the image has enough pixels for them.

Two things worth knowing:

• Enlarging does not add detail. Software can invent pixels, and modern tools do it well, but it cannot recover information that was never captured.
• Images taken from a website are almost always too small. They are sized for a screen, which needs a fraction of the data print does. Find the original.

Logos are the exception, and should be vector. A vector logo is stored as shapes rather than pixels and can be scaled to any size with no loss at all. If you only have a logo as a small image file, having it redrawn as vector once is worth doing — it removes the problem permanently, for every job afterwards.

Fonts: outline them, or send them

A print file that references a font the press does not have will substitute something else, and the substitution will not be reported to you — it will just be there in the printed job.

Two reliable ways to avoid it:

• Convert text to outlines before exporting. The text becomes shapes and can no longer be edited or spell-checked, which is why you should do it on a copy and keep the editable original.
• Embed the fonts in the export, which most PDF export settings will do if the licence permits.

Either is fine. What is not fine is sending a file with live text and hoping.

How to supply the file

A print-ready PDF is the most portable format, and the one least likely to change on its way to a press. When you export it:

• include bleed and crop marks;
• embed or outline all fonts;
• embed images at full resolution rather than linking to them;
• flatten transparency if the job is going to an older workflow — worth asking which is expected.

If you are sending working files instead, send everything the file depends on: linked images, fonts, and any placed logos. A layout file on its own, with links to images on your own computer, will not open correctly anywhere else.

A short checklist before you send

• The document is set up at the final trim size, not a scaled version of it.
• Bleed is present on every side that has background running to the edge.
• Nothing important sits inside the safe margin, including on folds and spines.
• The colour mode is CMYK, and any colour that must match is identified by a reference.
• Images are large enough for the finished size, and the logo is vector.
• Fonts are outlined or embedded.
• Every phone number, email address and URL has been read aloud and checked against the source — by someone who does not already know them by heart.

The last one is not a prepress issue, but it is the reason more print is reprinted than all the others put together.