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Reinventing the (Colour) Wheel

Guess what, all you people-who-see-colours out there? I’m going to say something that might be fresh news to you:

Red, Yellow and Blue are not the primary colours from which you mix all other colours.

Your computer printer has it right, they are: Cyan, Magenta and Yellow (or Red, Green and Blue, but we’ll get to that).

It is highly likely that Red, Yellow and Blue as primary colours were taught to you in school, and that is largely how it is still taught. You can certainly mix a lot of colours using that colour theory, it’s just not the most effective. Perhaps it is just the fact that the old ways are very ingrained (this colour system was adapted when we had less understanding of the human eye), perhaps because its seen as “easier” by those familiar with the old system. But it really needs an update.

So, what on Earth is going on?

Colour and its perception is incredibly complicated, so I’ll attempt a basic explanation.

In theory, when you’re painting you can choose any 3 colours to be your primaries - the ones you choose to make all your colours from. As a result, there’s an infinite number of colour system options. However, there are definitely more effective combinations - colours that will combine together to make the absolute widest range or gamut of colour options.

It makes sense that the most effective colour systems are those which work the most closely with the structure of our own eyes. Our eyes contain millions of light sensing cells known as rods and cones. The cones are the bits that distinguish colour and come in 3 types that detect short, medium and long wavelengths of light, that (very simplistically) correspond to blue, green and red. Each cone can perceive its main colour, but also a scale of colours on either side, so for instance we can see the colour yellow because of a triggering of a combination of the red and green cones.

Additive colour system

So you’d believe then, that because it matches our cones, Red, Green and Blue would act as the best primary colours. And that’s true... In fact, the RGB colour system is what we use to produce colour images from light sources (like phone, TV and computer screens). Our screens, for example, produce colour by emitting tiny light beams from a combination of red, green and blue diodes and they can certainly achieve images with a depth of colour for us to perceive that are rich and realistic. This is called the “Additive” system of colour. If you add “pure” red, green and blue lights together, you get plain white. In the additive system, the light is going directly to our eyes, so the best colours to use to create the widest gamut of colours indeed is that which matches our cones: Red, Green and Blue (RGB)

So where does the Cyan, Magenta, Yellow business come in, you ask?

Subtractive colour system

Well, there’s a second way we see colour: The “Subtractive” way. “Additive” is when coloured light shines directly into our eyes. The second way we see light is by having it reflect back off objects. If white light shines on an object, certain wavelengths are absorbed (subtracted) and then others are reflected. We see the colour of the object based on what colour it has reflected back at us. If white light shines on an object and all the colours are absorbed we see black. In a subtractive system, a certain reflected colour we see is actually the opposite of what was absorbed. This secondary step for perception results in a second set of primaries that its actually the opposite of Red, Green and Blue: Cyan Magenta and Yellow (check out a RGB spectrum colour wheel and you’ll see CMY in the opposite spots). Because paint, ink (and most of our viewed world beyond screens) relies on the subtractive system, Cyan, Magenta and Yellow are actually the most effective primaries for doing stuff like painting.

CMY and RGB together...

So… if you’re making colours with light (ie. direct light to your eyes like on a screen), use RGB for creating the best colours, if you’re making colours with anything else (ie. light reflected off objects), CMY is the way to go.

What about “K”?

To avoid confusion (?) with Blue, “K” in printing refers to Black. People who work in print or paint will know that colours and pigments are rarely super pure. Combining cyan, magenta and yellow ink, for instance, should produce perfect black, but in reality the result can be a bit muddy. To improve on this, most printers also include a dedicated Black premixed ink in addition to CMY for a better result. A single spray of black ink will also (usually) produce a crisper result than an overlaid heavy spray of all of the colours.

Why do I mix paint colours and they don’t come out like the colour wheel says?

Well, as you might have just learned, maybe you weren’t using the right primaries. However, some colours are just easier to mix than others. Magenta and yellow reliably give a pretty good orange, but other secondary or tertiary colours (like purple) can often turn out muddy. This has got a lot to do with the actual ingredients of your paint. In particular, cheap paints can have fillers, binders or just cheaper pigment bases that can interfere with your colour mixing. Whatever brand of paint you choose to use, you’ll need to find the best colours to suit your purposes. It is likely your colour palette will extend to a number of primaries to achieve the biggest selection of colours, plus some favourite colours that you use a lot or are just difficult to mix. Start with the colours closest to cyan, magenta and yellow, then work from there.

This is an example. I primarily use Winsor and Newton watercolours and this is their particular suggestions for primaries across their 2 watercolour ranges. The 3 part system is the basic, then they add slight variations of similar hues to extend the range.

Professional Water Colour 3 colour system

• Winsor Lemon

• Winsor Blue (Red Shade)

• Permanent Rose

Professional Water Colour 6 colour system

• Winsor Lemon

• Winsor Yellow

• French Ultramarine

• Winsor Blue (Green Shade)

• Permanent Rose

• Scarlet Lake

Cotman Water Colour 3 colour system

• Lemon Yellow Hue

• Ultramarine

• Permanent Rose

Cotman Water Colour 6 colour system

• Lemon Yellow Hue

• Cadmium Yellow Pale Hue

• Ultramarine

• Intense Blue

• Permanent Rose

• Cadmium Red Hue

So, throw the old Red, Yellow, Blue misconceptions out the window, everyone. If you’ve still been mixing paint with the old system, have a shake up and see if your colours find some new life (and some extra ease) with new primaries. I’m off to experiment some more.

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