Packaging Artwork File Preparation: The Complete Print-Ready Checklist

1. Colour Mode: CMYK, and When to Convert

Screens emit light and mix red, green and blue. Presses lay ink and mix cyan, magenta, yellow and black. The two describe different ranges of colour, and RGB describes a considerably wider one. This means a colour can exist on your monitor that no combination of process inks can reproduce, and when the file is converted the press will substitute the nearest achievable colour. That substitution is where the disappointment happens: a vivid RGB green becomes a duller, greyer green, and if the whole design was balanced around that green, everything around it now looks wrong. Working in CMYK from the outset means you are designing within what the press can actually deliver, so there is no unpleasant surprise at conversion. If a brand colour genuinely cannot be reached in CMYK, that is an argument for specifying it as a spot colour rather than accepting the substitution.

2. Resolution: 300 PPI at Final Size

The standard for commercial print is 300 pixels per inch, and the phrase that matters is at final printed size. Resolution is not a property an image carries independently of scale. A photograph that reports 300 PPI in its metadata and is then enlarged to double its dimensions on the page is delivering 150 PPI to the press. The reverse also holds: an image scaled down gains effective resolution. Check the effective PPI in your layout application rather than trusting the source file, since that figure accounts for the scaling you have applied. Vector artwork — logos, type, rules, shapes — has no resolution and scales without limit, which is why logos should always be supplied as vector rather than as a placed image.

3. Bleed and Safe Zone: Two Different Problems

Cutting and folding are mechanical operations with real tolerance. Sheets shift by fractions of a millimetre, and across a stack that variance accumulates. Bleed and safe zone are the two independent protections against it, guarding against opposite failures. Bleed means any background, image or colour that is meant to run to the edge must actually extend 3mm beyond the trim line, so that if the cut lands slightly inside the intended position there is still artwork there rather than bare paper. Safe zone means text, logos and anything else that must not be clipped are kept 3–5mm inside the trim line, so that if the cut lands slightly outside, nothing important is lost. Designers who understand bleed frequently forget safe zone, and the result is a beautifully bled background with a phone number sitting 1mm from the edge that gets shaved on a third of the run. On folding cartons and rigid box wraps, keep clear of creases as well as trims — content crossing a crease will distort.

• 3mm bleed on every edge that carries artwork to the trim.
• 3–5mm safe zone inside the trim for all critical content.
• Extra clearance either side of a crease or fold line.
• On rigid box wraps, allow for the turn-in around the board edge.

4. Fonts: Outline or Package

A font that is not present on the machine opening the file will be substituted, silently, and the substitution will reflow the layout. There are two reliable solutions. Outlining converts every character into vector shapes, so the type is no longer text and cannot be substituted — this is the safest option and the one to use when the artwork is final. The trade-off is that outlined text cannot be edited or spell-checked afterwards, so always keep an un-outlined master copy for yourself. The alternative is packaging the fonts alongside the file, which preserves editability but depends on the licence permitting redistribution. If a job goes to press with live fonts and no packaging, a substitution can pass unnoticed through proofing and appear on the finished run.

5. The Dieline Layer

For any die-cut item the dieline is the master template, and how it is supplied in the file matters as much as the artwork itself. It should sit on a dedicated layer named unambiguously, drawn in a spot colour created for the purpose — conventionally separate spot colours for cut, crease, perforation and glue area, so the toolmaker can read them apart. Every dieline element must be set to overprint so it does not knock out the artwork beneath it, and it must be excluded from output so it never appears on the printed piece. The most common error is a dieline drawn in a process colour, which then separates onto the printing plates and appears as visible keylines on the finished box. The second most common is artwork built to a dieline that was subsequently modified, so the two no longer correspond — always confirm you are working to the current version.

6. Rich Black and Small Text

Black is not one thing in print. Single-channel black, written as 100% K, is one ink. Rich black adds percentages of cyan, magenta and yellow beneath it to produce a visibly deeper, denser black. Each has a correct use and swapping them causes visible problems. Large solid black areas printed in 100% K alone look weak and washed out, sometimes almost charcoal, because a single ink film cannot achieve full density across a broad area — those need rich black. Small text and fine lines printed in rich black require four inks to register perfectly against each other, and any registration variance produces coloured fringing that makes the text look blurred — those need 100% K alone. The working rule is rich black for large fills, single K for anything small or fine.

7. Spot Colours, Varnish and Foil Layers

Anything that is not process ink needs its own defined spot colour so it can be separated correctly. Pantone brand colours should be applied as the actual Pantone swatch rather than as a CMYK approximation, so the press knows to mix the ink. Spot UV, foil and embossing each need a separate layer showing the exact shape of the effect, drawn in a distinct spot colour named for what it is, set to overprint. These layers are instructions rather than artwork — they tell the finishing equipment where to apply the effect. Two details cause most of the trouble here. First, unused spot colours left in the swatch palette can generate phantom separations, so delete any that are not in use. Second, a spot varnish or foil shape should be pulled very slightly inside the printed element it sits on, so that normal registration tolerance does not push it past the edge and create a visible halo.

8. Overprint and Knockout

By default, an object printed over another knocks out the area beneath it so the inks do not mix. Overprint disables that, letting the upper ink print directly on top of the lower one. Both behaviours are needed, and both cause problems when applied by accident. The classic error is white text accidentally set to overprint: white ink does not exist in standard process printing, so overprinting white produces nothing at all and the text vanishes from the finished piece while appearing perfectly on screen. The opposite error is a dieline or varnish layer left on knockout, which punches a hole through the artwork beneath. Turn on overprint preview in your layout application before you export, because it is the only way to see what the press will actually do.

9. Exporting and Packaging the Files

A PDF written to a print-ready specification is the standard deliverable, because it flattens the uncertainty of application versions, missing links and font availability into a single self-contained file. Export with bleed included, crop marks on, images uncompressed or minimally compressed, and fonts embedded. Do not export at screen or smallest-size settings, which downsample images destructively. Alongside the PDF, supply the packaged native file — layout document, linked images and fonts collected into one folder — because if a late correction is needed it can be made properly rather than patched into the PDF. Name files so they identify themselves without needing the email they arrived in: the item, the dimensions, the version and the date.

• Print-ready PDF with 3mm bleed and crop marks.
• Fonts embedded in the PDF, and outlined in the artwork where final.
• Native layout file with all links and fonts packaged.
• Dieline supplied both within the artwork and as a separate file.
• Clear file naming that survives being downloaded out of context.

10. A Pre-Flight Checklist

Run through this before sending. Most of it takes a few minutes and each item corresponds to a failure that is expensive to discover after plates are made.