Every week, our pre-press team flags artwork from clients who are experienced, intelligent business people, but who have made one of a handful of entirely avoidable technical errors. These mistakes delay projects, inflate costs and occasionally result in printed work that has to be reprinted entirely. This article documents the ten most common ones, so you never have to make them.
1. Resolution Below 300 DPI
Screen resolution is 72-96 DPI. Print requires a minimum of 300 DPI at the output size. An image that looks sharp on your monitor will print visibly blurry. The critical mistake is not the original image quality, it's scaling a low-resolution image up in your layout software. A 300 DPI image at 10cm will not remain 300 DPI if you scale it to 30cm. Always check effective resolution in your layout application.
2. Artwork Supplied in RGB Instead of CMYK
RGB is the colour model of screens; it uses light to create colour. CMYK is the colour model of print; it uses ink. Converting RGB to CMYK at the press causes unpredictable colour shifts. Bright digital blues frequently become dull greys. Vibrant greens shift toward yellow. Set your document to CMYK from the very first moment you create it, and proof all colours against a printed CMYK swatch, not a screen.
3. No Bleed or Insufficient Bleed
Bleed is the extension of your background colour and imagery beyond the trim line of the document, typically 3mm on all sides for standard print, and up to 5mm for large-format work. When print sheets are trimmed, there is always a small margin of cutting tolerance. Without bleed, that tolerance produces a white edge on your finished piece. Background colour, patterns and images that touch the edge of the document must extend to the bleed boundary.
Other Critical Mistakes to Avoid
- Fonts not embedded or outlined, text reflows to a default font on machines without your typeface installed
- Text placed inside the safe margin (5mm from trim), text at the edge risks being cut off during finishing
- Using black text that is set to 4-colour black (C60 M40 Y40 K100), causes registration misalignment and blurry text; use pure K100 for all body text
- Transparent elements in files supplied as PDF/JPEG, flatten all transparency before export
- Supplying JPEG files at quality 8 or lower, JPEG compression artefacts are visible in large-format printing
- Incorrect document size, always set up your document at the actual final size, not proportionally scaled
- Missing linked images, always package or embed all linked assets before supplying artwork
The best creative idea in the world is undermined by a technical error at pre-press. File preparation is not an afterthought; it is part of the design process.
Ama Boateng, Senior Designer
