: How heavy should ink coverage be for a custom CMYK rich black? In recent jobs, I have skewed away from pre-mixed rich black formulas in favour of making a black that fits dominant colours

@Angie364

200%-300% Never over 400% sweet spot is ~220-250%

Generally you base the % coverage of inks off several factors.


Your 4-color proof
Paper weight being used <---Most important
Paper color (Cyan vs Yellow) <---Most important
Press limitations


Once you take all those factors into account you can make your black and run some test prints.

I don't think I have adjusted blacks ever to match the art outside of pre-press. In all my experience it's the paper color and its absorption ability that matters the most. If you build a green-tinted black but your paper is yellow it's going to look bad.

Usually a 40-40-40-100 works just fine, otherwise I go for a deeper 60-60-60-100.



However

I don't really understand why you are going about it this way, I don't see much gain from trying to create a black that mirrors it's content. The point of black is to create divides and visually break-up a piece. This is actually a bad idea that could mess-up an entire run.


If a black is enriched for no reason on small characters or graphics,
the result might not look as sharp as when using a pure pure because
of the misregistration. When press operators calibrate the job at the
beginning of the print run, they need to adjust the 4 CMYK plates
together and very precisely. That's not an easy adjustment; sometimes
they don't really care if it's a low quality print place and sometimes
it's their old machines that cannot keep that adjustment for the whole
print run. All print shop are not equals, the human factor and
investment in good machinery can have a huge impact on the print
quality.


Yes I get that sometimes you need to tweak it but I don't think this should be a "standard practice" you should implement.


To create a fitting rich black for this identity, my first impulse was
to add half the cyan and Yellow values to the existing 100% black.
That yields C25 M0 Y50 K100. Is that too light?


That sounds about right generally you want to be within 5% of the original coverage. Here you are 6.8% so not bad but again depends on all of the other factors.



Bottom line

Check with your press operator, know your paper and know your art.

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@Goswami567

Ok, I think this question is quite difficult to answer because there could potentially be many variables at play. I'm just going to concentrate on the practicalities of printing the job, so you don't upset your printer with your novel choices of mixes for rich black.

I assume, it's four colour process offset lithography.

It might depend on the press and the amount of coverage required, even the stock it's being printed on, or whether it's being UV coated, etc, etc. I worked in offset litho for many years. Sometimes the printers would nearly have a fit when they realised a certain colour mix was virtually unprintable, or would give them significant problems during the run.

For example in small offset lithographry, some smaller presses don't have quite the roller power for large areas of solid ink coverage - combine that with the actual system whether it's a full colour press, or perhaps two-colour being printed in full colour but in two passes, and therefore the possible contamination of colours in the second pass, from blanket to plate, and back into the ink.

Another possibility is that if there is too much total ink it could cause problems with drying (again depending on the stock), or even offsetting on the backs of sheets etc.

There are so many practical reasons I think I would want to ask my printer about this before just assuming that they can print it.

My advice - talk to your printer first, don't upset him!

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@Kimberly620

There is no answer to your question as such: everything above C0M0Y0K100 is darker than process black. However, consider that 100% ink means that your printer fills the entire raster, while 25 fills only a quarter of a raster.

This means that the lower the value of your other colors the more uneven it is, so it might be perceived as grainy. So while M100 K100 is extremely even, C25 M0 Y50 K100 might appear more uneven. How grainy people perceive it is hard to say, since it depends on the medium, print resultion, raster type and distance to viewer. Most likely this is not really an issue.

However if you go for dark BLACK with a hint of undertone, then I would fully saturate the primary color and add black. Then bring it down to a 200-300% coverage range.

But then I have the option to make test prints (and sadly, the duty to clean the machine if I just get the color all over the place). So I would print a few swatches.

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