Are complementary color mixes nicer than black mixes?

Darkening colors with complementary colors (such as adding red to green) looks nicer than darkening them with black. This is one of the most common pieces of conventional wisdom about color mixing; it’s one that I also believe on an emotional level and have repeated many times. But is it true?

I’m really asking! I don’t know.

What Others Say About Mixing with Black

The word “dead” is most common: black “looks dead.” The more I think about it, the less I know what this means.

I find pre-mixed black watercolor too dead and neutral. It will certainly put plenty of tonal contrast into a painting, but making the darks lean either towards cool or warm puts a lot more life into the work.

John Lovett

 Blacks and grays tend to look lifeless, unless they are mixed with other pure colors. To create darks that aren’t dead looking, use mixed colors to form darks.  Think of your darks as color opportunities!

Rebecca Zdybel, Paintings with Punch! How to get dark values in your watercolor (2016)

Black as also generally avoided as it can have a deadening effect on the other colours, though a convenient dark is very useful. There are a few different forms of Payne’s Grey and Neutral Tint. Notice that most of them contain black, except the M.Graham Neutral Tint which is wonderfully dark but made PG7 and PV19. My preference is to make my own darks, my favourite being Jane’s Grey, a mix of Ultramarine PB29 and Burnt Sienna PBr7,

Jane Blundell, Light, Grey and Black Watercolour Swatches

My Little Experiment

I performed a small test by adding various colors to Phthalo Green to make dark green. These are all done with gouache, which eliminates any variation from watercolor transparency and granulation.

Here’s my review of each of these mixes:

• M. Graham – Lamp Black (PBk6): My “mix with black” control. Actually, this looks fine to me.
• M. Graham – Payne’s Gray: A mixed gray using primarily Ultramarine Blue, this definitely has a cooler appearance.
• Winsor & Newton – Perylene Maroon (PR179): This is too warm and causes the green to become brown. Still a useful mix, but not a complement.
• Schmincke – Vermilion Hue (PR255): Also too warm and browny.
• M. Graham – Quin Red (PR209): This is a pretty good complement, and makes a strong black.
• Holbein – Primary Magenta (PR122): Too cool, mixes a dark blue/violet color.

So in effect, I’m comparing the Lamp Black mix to the Quin Red mix.

I have to say, I wouldn’t say one is nicer than the other. The Quin Red mix is streakier because I couldn’t get as strong a mix of gouache with more transparent pigments, but this is unrelated to the hue. Just based on the color alone, I don’t think I could tell them apart in a blind taste test.

Theories

This limited test is hardly conclusive, and I won’t say I’ve proven that mixes with complements and mixes with black are equal. However, it has given me some ideas on why people might think and say that complement mixes are nicer, even if they’re not detectably different.

1. It’s magic to watch complements mix black. It’s counterintuitive to me, and I find it fascinating to watch. Adding bright red + bright green and getting black is fun, adding black and getting black is dull. Because the process was more fascinating, people think the end result is more fascinating.
   
2. Most “complements” are not exact complements. Mixes with black always turn more black, while mixes with complements are usually slightly off-black. In these examples, for example, mixes often ended up slightly too blue or slightly too brown. My theory is that people don’t actually want black, whether they know it or not; they want something that’s a bit warmer or cooler.
   
3. In watercolor, mixes can get darker than single pigment colors. In watercolor, I have anecdotally observed that it’s difficult to find a single pigment that gets and stays very dark (in any hue). All blacks, dark blues, dark reds, etc seem to have high drying shift. When you mix your own blacks, you can ensure the mix has the properties you want. In gouache this does not seem to be as much of a problem (although in gouache, I see people speaking out against black less often; gouache artists are more likely to call it a must-have color.)

What do you think? Do you avoid mixing with black? Do you think mixes with complements look better, or can you not tell the difference?