InDesign’s preflight panel is a great tool. as mentioned previously, live preflight is a dog, but the preflight panel is pretty much a compulsory tool for anyone sending stuff to print.
however, there’s still no substitute for doing your own manual and visual checks of a document before sending it out into the world. just as spell checking and grammar checking are no substitute for a proper proof read.
one invaluable feature which you should take a look at before sending EVERY job to print is the separations preview panel — if only to check your black plate. here’s a simple job about to go to press — boring design, yes, but looks fine to go :
the first is the spot colour (this is supposed to be a process job). whether or not that would be picked up by your preflight panel depends on how you’ve set it up. but this is a problem easily spotted in your swatches panel too.
the other two problems are highlighted by turning off the black plate in the separations preview panel (click on the eye to turn it off). you’ll notice all the black text has disappeared — this is how it should be.
that graphic is going to be a bitch to print — especially those fine diagonal lines — you’re just about guaranteed to get coloured halos around those lines when the heavy CMY plates hit the sheet (note: you can get readings of ink coverage by hovering your mouse over part of your artwork. the readings in the screen grab are from that graphic). BEWARE — images downloaded from online sources will not necessarily be well prepared.
ok, the last problem is that first bit of black type knocking out the coloured background. again, you’re creating a potential registration problem on-press with this fine type knocking out — it should overprint. in this case the problem is due to the type being inadvertently set to 99% black (as soon as type is anything but 100% black, it will knock out by default).
so there you have it — two common black plate issues which will not be picked up by your preflight panel but which could still compromise the quality of your printed job. remember — when sending a job to print — ALWAYS check your black plate in the separations preview panel.
… and keep grunting