A sales rep puts the new catalogue next to the product. The navy casing has come out purple in the photo, and the customer asks which colour is the real one. The whole run is already sitting in the warehouse. A proof is there to catch this before the press starts.
An ordinary monitor won’t show it. Every screen has different settings, and none of them knows what paper and inks the job will be printed with.
Types of proof
- Certified proof. Printed on a calibrated device and special paper so that it simulates specific print conditions, such as offset on coated paper. It has a measurable control strip and a note of the profile used. The printer compares the sheets on press against it.
- Soft proof. A PDF viewed on a calibrated monitor with print simulation. Quick and cheap, but only as good as the monitor and the eye of the person looking at it.
- Test print. In digital printing this is often the simplest route, because the sample comes off the same machine, on the same paper, as the run.
A print from an office printer is not a proof. It knows nothing about the inks or paper the job will use, so it says very little about colour.
When to order a proof
A proof costs money and adds time. It pays off where colour sells or is part of the brand: product photos in a catalogue, a brand colour on packaging, a large offset run. For a few dozen digitally printed leaflets, a test print is usually enough.
Once signed off, the proof becomes the reference. The run is later checked against it, not against a monitor in the office. What a proof can’t show are finishes such as spot varnish or foil, or the texture of a speciality paper.