Do You Watch the "K" in Coloring?

A genuine question to my fellow comics and graphic novel creators

Today, we dive into something a bit technical: adjusting colors when painting digitally for comics and graphic novels.

And while we’re at it, I do have an open question for those who friends who are much more knowledgeable than I am on this topic. I’ll ask that towards the end of the post.

As a rule of thumb, when we create graphics for prints, we make sure the files are set up correctly. Print files are always set up in CMYK (Cyan, Magenta, Yellow, Key), not RGB (Red, Green, Blue) mode.

(You want to make sure you’re not working off RGB. As you can see, RGB has a slightly wider range, especially in the greens. If you select a pop green color in RGB, it’s going to be significally duller once you print it in CMYK.)

Most printers use black as the key, so we associate “K” as “black”.

Professional comic colorists always aim for 0% for K and adjust CMY to match their existing colors.

Let’s say, you have this orange. Notice CMYK is set at C25 M64 Y75 K18.

You want to then pick a color where K is 0, and re-adjust CMY to the closest orange you can match it with. I have now matched the orange to C39 M71 Y86 K0.

As you can see, the new color where K is set at 0 is very close to the old color I originally picked. At least they’re close enough for my eyes. And I know in the back of my head this works better for print.

The main reason is the same reason why we avoid using black straight off the tube when we paint: black fresh off the tube looks flat. Any time you put black in your color, the color ends up looking dull.

Mixing your own black gives you more options in developing depth. It breathes more life and layers to your artwork.

I’ll give you an example.

In “MY LITTLE SISTER AND ME,” I mixed phthalo blue with burnt umber for the kids’ hair to make them pop. The overall composition for this book was designed simpler, and I needed something to pop so make the visuals more fun.

A more power black is mixed for the kids’ hair.

In “DIM SUM, HERE WE COME,” I mixed quinacridone rose with phthalo green for the kids’ hair to convey a softer black to match the overall palette. The compositions in this book were busier, so I needed a bit more harmony to avoid visual overloads.

A softer black is mixed for the kids’ hair.

By mixing my own black, I have more options to play with. Not to mention this avoids a flat and dull look to the painting.

The same concept applies to setting K at 0% when coloring comics and graphic novels. By doing so, we avoid colors turning out muddy and dull on final prints.

(Note: I don’t think it works the same in digital painting. It applies more to comics and graphic novels because we usually work with a very selective and limited color palette.)

So, here comes my question to my professional colleagues / art directors / designers / production designers who are infinitely more knowledgeable than I am:

When you build your color palette, do you make sure K is at 0?

The reason I asked is that I don’t hear often this gets discussed. This is VERY comics and graphic novels specific when it comes to coloring and the printing process, and I’m genuinely curious!

And I am learning! Always. :-)

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Update on March 2024: On this post, I talk about a Photoshop extension I recently discovered that can lock K at 0%. Check it out!