Now that we’ve set the mood, let’s talk about black ink
What is black, anyway? Conceptually, “black” isn’t a color, it’s the absence (or near absence) of light waves reaching your eyeball. This happens by either shutting off pixels in a display, or creating a surface that doesn’t reflect ambient light. There’s a color model for each.
RGB Pixels, or Additive Color: The red, green, and blue primaries in this model match the receptors on your own retina, so you might say RGB is your eyeball’s native language. To render “Black” the definition is RGB 0,0,0; and this gives you a blank screen on smartphones, monitors, and projectors.
Since printing relies on reflection, not projection, we can’t directly print in RGB. A translation is needed, and as with two fundamentally different languages it’s never perfect. “Black” in RGB often translates to a printing color that doesn’t include 100% of black ink (CMYK 75,67,67,90). This unpredictability is just one of many reasons to select CMYK for your print document color space, and color definitions, unless there’s just no choice.
CMYK ink and toner, or Subtractive Color: The language of almost all color printing, CMYK is the reciprocal of RGB. In the diagram you can see that the primaries of one model are the secondaries of the other. In theory 100% Cyan, Magenta, and Yellow would equal black, but they don’t so our print-shop founding fathers added black ink as a fourth color and we’ve lived happily ever after.
For clear, sharp type we want 100% black and nothing else so that the edges of the letter forms won’t be compromised by other colors peeking out. But is 100% black always black enough? What if your layout has a gigantic solid black background, and we’re worried about the possibility it’ll show pinholes, grayness, or we’ll have to run so much ink that adjoining graphics will start to plug?
Rich Black is a color swatch that can be created to alleviate the problems of a large, 100% black solid. In your layout program simply build a color swatch in CMYK with these numbers, CMYK = 30, 30, 30, 100. Use that swatch if you want to create large areas of solid black, and we’ll easily lay down a dependable impression with real depth and uniformity. To travel from the sublime to the absurd, however, follow me one step further.
Image Credit: Surrey NanoSystems
Vantablack, from Surrey NanoSystems, is the extreme end of subtractive color, and has been employed effectively by cartoon roadrunners since the 1960’s. It’s carbon fiber nanostructure absorbs (does not reflect) in excess of 99.9% of visible, ultraviolet, and infrared light. Objects sprayed with an aerosol version of the product appear two-dimensional, which is a clue to the degree we depend on variances in reflected light to orient what we’re seeing.
So far we can’t print this stuff, and assume most uses are super hush-hush, but if you want to be at the cutting edge of dark-black technology there’s a watch available made using Vantablack that only costs $95,000.
For those of us who aren’t that rich, there’s always rich black.