A proof is your last opportunity to catch problems before a job goes to press. It is also the point at which responsibility for the final result shifts from the printer to the client. Understanding what proofs can and cannot tell you — and knowing how to evaluate them properly — is one of the most practical skills in managing print production.
What is a proof?
A proof is a representation of how the finished printed piece will look, produced before the full print run begins. Its purpose is to allow you to check the content, layout, colour and overall appearance of the job, and to identify any errors or issues that need to be corrected before production. Proofs serve two functions: quality control and approval. A signed-off proof is a contractual document: it confirms that you have reviewed and accepted the artwork, and it defines the standard against which the finished job will be measured.
Types of proof
Digital soft proof (PDF proof): the most common type. Your artwork is processed through the printer's prepress workflow and output as a PDF that you view on screen. Fast and economical, but cannot accurately predict the exact printed colour. Digital hard proof (inkjet proof): a physical print produced on a calibrated inkjet printer. A reasonably accurate representation of the final printed result. Contract proof: a physical proof produced on calibrated equipment to a recognised colour standard (typically ISO 12647-7). The most accurate colour reference available before going to press. Press proof: a proof produced on the actual production press — the most accurate proof possible, but also the most expensive.
Why printed colour differs from screen colour
Screens create colour by emitting light (RGB). Printed materials create colour by absorbing light (CMYK). These are different physical processes with different colour gamuts. The RGB gamut is significantly wider than the CMYK gamut, which means there are colours that a screen can display that simply cannot be reproduced in print. Additionally, screens are backlit and viewed in a range of ambient lighting conditions. Printed materials are viewed under reflected light, which varies enormously depending on the light source. Paper also affects colour — the same ink on a gloss coated stock will look more vibrant and saturated than on an uncoated stock.
How to evaluate a proof effectively
Check the content first: read every word, every phone number, email address, web address, date and price. Check the layout: are all elements in the correct position? Check the images: are all images present and correctly positioned? Check the bleed and margins: does the artwork extend to the bleed line? Is all important content within the safe zone? Check the colours: do the colours match your expectations? Check for technical issues: are there any visible artefacts, banding, or moiré patterns?
Approving a proof
When you approve a proof, you are confirming that the content and layout are correct and that you accept the colour representation shown. Once a proof is approved, the printer will proceed to production based on that approval. Read the approval confirmation carefully. Most printers include language that limits their liability for errors that were present in the approved proof. At Astro Graphics, we issue a digital PDF proof for every job and require written approval before proceeding to production. For colour-critical work, we recommend a physical proof and are happy to discuss the options when you request your quote.