16 July 2009

[print tech] I May Not Be Rich, But My Black Is

2153.I got a tipoff to a great article today about three sins in print design, and they're good things to remember.

They reduce down to three things they even teach you in Community College design school, they are that basic. they are, in order: Designing in RGB rather than CMYK; using black rather than "rich" black; and not using 300 dpi images in designs meant for print.

The first and last can make up an article all on thier own. But the second really caught my attention, because I also have a love of words that make things that don't necessarily happen together stick in the mind. Though the idea of "rich" black should stick in every print designer's mind.

Okay, enough circumlocution, and besides, what non-designer readers might want to know is, just what is rich black (disposing of the quote marks hereinafter)? It's pretty much what it suggests it is: black with a little "something extra".

Color print (other than spot printing) involves using the four so-called process colors cyan (C), magenta (M), yellow (Y) and black (K) to create the colors you see on the final product. Nothing is perfect, so CMYK can't produce every color you find in nature, but the gamut (a color theorist term for the range of possible colors that can be produced) is wide and useful enough that you'll never run up against a wall. Since inks aren't perfect, then black isn't perfectly black. You have to give it a little help. How? By adding one of the C, M, or Y inks.

On the left, true black @ K=100, On the right, rich black at C=90,
M=60, Y=30, and K=100. Inspired by the linked article.

Long ago, some wag said you can never be too rich or too thin. In the CMYK model, that's only half right: as you can see, you can indeed be too thin. True black ink, printed at 100%, may seem black, but when put up against rich black, it seems gray. A very dark gray, to be sure, but unmistakably gray. You amp up that black by throwing in a bit of one, two, or three of the other process colors.

Amusingly (and perhaps predictably) there is more than one opinion as to what constitutes a good rich black. One of the commenters in the linked article, Darren, put it in a way that's both interesting, has a clear grounding in color theory, and is easily rememberable:

I am a prepress technician and a true rich black or super black is 100% K and 40% Cyan for a cool black or 40% Magenta for a warm black. Don’t use any other percentage combos as they cause problems for the printer. Also don’t use a rich black for any text under 20pts (printers hate that). And if you do any of the above most printers will convert your pdf to the percentages I have above. Only use it for large black areas and text over 20pts.
And that's another thing: rich black isn't ideal for every part of the application. True black is typically adequate for small black areas and type you're going to be reading; the more ink you use, the more saturated the paper is going to become, which has the unfortunate tendency of munging up the works.

But if a real good black is part of the overall design scheme, you'll want to remember to use rich black. Black is a powerful color, and if you're looking to make an impact with that design, you'll want it to crackle and pop, and if you take the edge off your black, the pop just won't be as large.

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