Print guides · 4 min read
Preparing artwork for the press: bleed, margins and colour
Most print delays are not caused by presses. They are caused by files. A design that looks perfect on screen can be unprintable as supplied, and every round of file correction pushes your delivery date back. Here is what a press actually needs, and the mistakes pre-press departments see every week.
Bleed: design past the edge
Printed sheets are cut to size after printing, and cutting is accurate to a small tolerance, not to a hair. Bleed is the answer: any colour or image that touches the edge of the design must extend about 3mm beyond the trim line, so a fractional drift in the cut never exposes a white sliver.
No bleed is the single most common file fault. It cannot be fixed by the printer without stretching or rebuilding your artwork, so build it in from the first day of design.
Safety margins: keep content off the knife
The same cutting tolerance works in the other direction. Text, logos and anything that must not be clipped should sit at least 3mm to 5mm inside the trim line, and on cartons, clear of crease lines too, since type folded over an edge becomes unreadable.
Be especially careful with borders. A thin frame running close to the trim will show every fraction of cutting drift as an uneven margin. Either pull borders well inside or drop them.
Images: 300dpi at final size
Print needs image resolution of 300dpi at the size the image will actually appear. A photo that fills a screen can still be far too small for a carton panel; enlarging it does not add detail, only blur. Check effective resolution after placement, not the file's label.
Images pulled from websites are almost never usable: they are low-resolution and RGB. Source originals from the photographer or brand library, and keep logos and diagrams as vector files wherever possible, since vectors scale to any size without losing sharpness.
Colour: CMYK, not RGB
Screens work in RGB light; presses print in CMYK ink, plus any Pantone spot colours you have specified. Supply files in CMYK. RGB files will be converted before printing, and conversion shifts colour, usually dulling the vivid blues, greens and oranges that look brightest on screen.
Do the conversion yourself, in your design application, so you see and approve the shift before the printer does. Define brand colours by their CMYK build or Pantone number rather than trusting an on-screen match, and name any spot colours correctly in the file so they separate onto their own plate.
Fonts and final files
If the printer opens your file without your fonts installed, the type reflows or substitutes silently. Avoid it by converting text to outlines in the final press file, or by embedding all fonts in a press-ready PDF. Keep an editable master for yourself; send the press a locked version.
A press-ready PDF with bleed, crop marks, embedded images and outlined or embedded fonts is the format every pre-press department prefers. For packaging work, include the dieline on its own clearly named non-printing layer, and never flatten it into the artwork.
Let pre-press check before you approve
Every serious printer runs a pre-press check on incoming files: bleed, resolution, colour mode, fonts, overprint settings and the dieline fit. Treat it as a service, not an obstacle, and build a day for it into your schedule. At PrintVision, pre-press review is a standard stage before any plate is made, because a fault caught in the file costs minutes, and the same fault caught on press costs a run.
The best insurance of all is a proof you actually read. Check the proof word by word against your approved text, because once you sign it, what is on that sheet is the job.
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