Colourful lies you learned before high school
The primary colours cannot be mixed from other colours. This is one of the fundamental lessons from an elementary school art education. Did you know you can mix fire engine red using yellow and magenta?
Wait, what?
Colour printers use cyan (sort of a powder blue), magenta, yellow and black ink, and they make scarlets and crimsons just fine. I knew this, but I was still surprised when I learned that red was a colour that could be derived from others. I’d never thought too hard about this contradiction between what I was taught as the truth about colour and my own observations of the world. Well, it turns out there's a rich history of humans struggling to find the primaries so I really don’t feel too bad.
In this (very long) webpage the author surveys 300 years of inaccurate or incomplete attempts at modelling colour, concluding that primaries would have to either be purely imaginary constructs or inadequate for creating the full spectrum of colour (this is because colour saturation goes down every time you mix paint or light colours). I am fascinated by both the human drive to figure it out, and the hubris of ignoring the pieces of reality that didn’t fit nicely into the model du jour.
So getting back to what I promised in the title: what other things did we learn about colour in school that aren’t quite right?
The different kinds of colour complements
Green is said to be the complement of red. Why does it clash so much, then? Middle school colour theory tends to conflate the visual complement of a colour and the mixing complement of a paint pigment or light.
Visual
The visual complement of a given colour is the colour against which it looks the most vibrant. Red’s visual complement is a blueish turquoise. You can see this for yourself by staring at a bright red object for 20 seconds, then looking at a white surface. What colour is the afterimage?
Other visual complement pairs (determined in the same way) are:
- egg yolk yellow and elementary school paint kit blue ("ultramarine")
- fuchsia pink and slightly blue greens like viridian
- eggplant purple and lime green
- sky blue and orange (Portal gun colours)
You can make some fun outfits based on these pairs, by the way. Using visual complement pairs is one way to create harmony in a colour scheme.
This is a colour wheel in which opposites along the wheel are visual complements of each other.
Light mixing
If you take a light mixing complement pair, then draw or paint densely packed dots alternating between the two colours on a piece of paper and then squint at it from far away, you should see a perfect neutral grey (if you get the proportion of one colour to the other correct). You are looking at the average between two different colours without mixing the physical paints. There will never be a neutral grey between red and yellow of course, but you won’t find one between red and green either.
Take a look at some of the middle colours in this gradient. It goes from green to reddish green to greenish red to red without going anywhere near grey! They are definitely not light mixing complements (and, against intuition and all manner of opponent process-based colour models, reddish green is a valid description of a colour).
Paint mixing
Where did the idea of red being opposite to green come from, then? Red pigments mix with (blue-ish) green pigments to make neutral greys, so green and red are (near) paint mixing complements. There’s not much to say here. I think middle school got mixing complements mostly right. There are some interesting textural effects from interactions between heavy metal-based pigments and "smaller" and "lighter" synthetic pigments, but that's not really important unless you are Really Into Watercolour.
Paint mixing complements, enumerated
So...now what?
You don't need a perfect understanding of how brains and eyes process colour to make or appreciate good art. Look around and question any prescriptive rules about what colours do and do not go together. There are some great examples outside, because nature never got the memo about what should and shouldn't work :) And if you know a kid, mix a primary (or two) in front of them. That's cyan + magenta = blue, and yellow + magenta = red. Highly entertaining all around.