Understanding and using separations
When colour separation was first introduced in InDesign I was ecstatic. It was just so awe-inspiring. It was like discovering Darth Vader was Luke Skywalker’s father all over again. Of course, my background being in the pre-press discipline this feature was of great interest to me. Not so much, however, for my fellow artists at my agency. They were unimpressed with this feature and were more impressed by the multiple undos function. HA – multiple undos? Really?
Okay, okay… that was also awesome.
Back in the day, during my early career, separations was a very important element in my workflow. As a pre-press artist I needed to inspect colour output to make sure only certain elements printed to the black plate while other items were overprinting or knocking out properly. Sometimes I would check trapping and general ink density as well. Film was expensive to output so the only way to preview separations was to output them to lasers. It was time consuming but not as much as the time and cost of outputting bad film. Separations were a great way to spot these issues before they became a real problem. Viewing separations digitally makes it more convenient than ever. Nowadays we try to conserve paper, but back then we were trying to conserve expensive film.
Today most of what I described above is handled by your printer and their sophisticated computer RIP systems. Yet by doing a quick check of the separations on your file you may prevent future printing issues with your design job.
Try this: Turn your your black plate on and off using the separation option. This is probably your most important colour with regard to finer image details and your job’s typography. Ideally your printer wants to print smaller reading type in single black only. It stays crisp and readable this way. If other colours are used to produce black type, it may become fuzzy due to slight mis-registration of colour when printing. If you turn off the black plate, all of your black type should disappear, because it is coloured 100% black instead of a mixture of colours (which appears black on your computer screen). If you still see the type on the other separations then your black type has been contaminated. Change your type to 100% black. This is definitely important for any type of scannable bar codes. Your code could possible be un-scannable if it accidentally prints in multi-colours because of the mis-registration problem.
Sometimes you may not want the overprint effects of black. By default all 100% black elements overprint in InDesign. This is desirable for most type elements. Yet if you have large black display type or black graphic elements applied over important images, the affects of overprint may not be desirable – like this:
If this is not what you want, then you need to go back into your file and turn off overprint on those elements. Again, most of the more important stuff gets fixed by the printer – but a quick check of your separations can help prevent these types of printing issues that may compromise your work as well as causing any unnecessary delays in your workflow.