How to Check a Printer's Proof
The main purpose of checking a printer's proof, is to make sure that what you get back from the printers is what you sent them. At this stage you should be checking for errors in output only. Things such as proofreading and checking the layout for the desired elements should have already been done by this stage. The proof should be checked against the final laid out draft for correctness.
Colour
Colours should be checked at this stage, although if the document contains spot colours, and the proof is a digital proof, printed in 4 colour process, the colours may not be exact. Please check this with your printer.
Image placement
Check the images are actually in place and in the correct place. Check the text inside images. In complex diagrams, check all of the elements.
Text
Check the beginning and end of each paragraph for position. Check these are in the same place on the printer's proof as on the signed off draft. If they are not it could be that something is missing, text has reflowed, or fonts may not be exactly the same. If the printer uses a different version of the font, it could cause reflow as subtle as one word dropping off in every 100 pages, but the word could be critical. Also remember to check special characters if used. If a font has been substituted special characters may not be the same.
Hyphenation could accidentally be turned on or off by the prepress studio. Check it is correct.
Check typeface visually to make sure the font is right.
Page order
If possible get an imposed mock-up from the printer and check the page order, or give the printer a properly imposed mock-up with the files.
Things that cannot be checked on a digital inkjet proof. Most printers today produce digital inkjet proofs of your page layout files via a postscript RIP (Raster Image Processor). Postscript files which contain a mixture of raster data, or pixels, and vector data, or lines, are processed in a RIP, and sent as pixels to output media such as laser printers, inket printers or plate makers. Once approved, these ripped files are then sent to the digital plate maker or film imaging unit. In doing this, the printer makes sure that the same file that was approved via the proof, is used for the final output, ensuring that what you approve at proof stage is what you will see after the document is printed.
Spot colour accuracy, metallic inks, dot gain, moire patterns (Patterns caused by incorrect screen angles, or a clash of the printed screen angles with patterns in the image.) cannot be accurately simulated on digital inkjet proofs.
These things can be checked on either a chemical proof, or a digital dot proof, such as a Kodak XP-4 proof, which almost exactly simulates the final printed dot and can therefore predict things such as dot gain and moire patterns. They can also be calibrated very closely to spot colours and metallic inks.
There is usually an extra cost associated with these types of proofs, and most printers do not offer them as a matter of course, but if you are concerned about the issues raised here, please ask your printer.
Checklist
- colour
- image placement
- text placement
- hyphenation
- typeface
- spot colour
- metallic ink