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Primary color theory – color mixing with essential watercolors


My name is Ilse and I’m the artist behind the Instagram page Stacey has been so kind to let me write a bit about watercolor, pigments and color theory – my absolute favorite subjects to talk about! She also made me extremely happy when she invited me to join her creative team, and I’m very proud to be representing her wonderful brand of watercolors!

Recently I found myself with a major artistic blockage, and no matter how much I looked at all my paint, I couldn’t figure out what to do with it. The solution came to me when I ordered a pocket-size palette and had to decide which colors to put in it. Limiting my palette made me look at my options in a different way; and having to argue which colors to keep made me appreciate each of them more than I did before. I began a project of exploring and presenting all my favorite colors, and in the process learned that other people was interested in this, too.

The main question I’ve gotten so far comes from people who are ready to invest in artist grade paints, and they want to know “what colors should I get first?”. Many artists find themselves with a limited budget, and choosing the right colors to begin with might be the difference between a blooming art journey, and a lot of frustration as your paints won’t do what you need them to do for your personal art style. Always when faced with questions like these, I default back to primary color theory – the color wheel most of us got to know as children. Red and yellow makes orange. Blue and red makes purple. And so on.

Primary Color Theory

The real science of primary color is a bit beyond the scope of this article, but we’ll focus on the part of it that’s most important for artists. The basic assumption is that there are some colors that can’t be achieved by mixing other colors, and that the rest of the colors of the spectrum can be mixed from these base colors.

However, primary colors must not be confused with single-pigment paints. When talking about primary colors we’re focusing on the color of the paint, and not the pigments it is made with. A primary yellow paint can consist of multiple pigments and still be within the limits of what we would call a primary color. This is because there are lots of different colored chemicals – pigments – that reflect yellow light. There are no primary pigments that you can mix to get any other pigment, the theory only applies to the actual color of the paint. Which is why it’s important to know the difference between colors and pigments, and why the pigments listed at the end of this post are simply suggestions for paints to use for mixing. You can read more about pigments in the next post of this series.

Another thing to keep in mind is that the theory doesn’t account for pigment particle behavior, or how paints interact with each other. But the theory should give us enough knowledge to utilise our paints in a more effective way.

Red, yellow and blue

When talking about primary colors, most people can identify these as red, yellow and blue. The theory goes that if you have these three colors in your palette, you can mix absolutely every other color in the world by adjusting how much of each primary color you include in your mix. But if you have tried to mix a seemingly pure red – think blood red, or ladybug red, the type of red that’s always included in a small packet of crayons – with a pure blue, you know that the purple that comes out of it is often dull and brownish. Why doesn’t this “primary red” yield the mixing result we expect from it? And which are the colors that actually mix purple?

Warm and cool colors

As painters we often come across an expansion of this principle which is called the “split primary” color palette. This theory is supposed to help us mix more vibrant colors, and it recognises that there are warm and cool shades to choose from. A cool yellow leans toward blue and might remind you of sour limes. A warm yellow leans toward red, and warm sunshine and sunflowers might come to mind. If we look at the red section of the color wheel, the “pure” red we talked about earlier would be considered a warm red, leaning towards yellow. The cool version would lean towards blue and we might call it magenta, or rose. A warm blue would be the classical ultramarine, leaning towards red. And a cool blue would lean towards yellow, maybe as far as being a turquoise.

This means that we would get different color wheels depending on which type of primaries we choose – warm or cool. In the two color wheels below I’ve split my primaries in two sets and painted out the secondaries and tertiaries I could get from mixing the primaries.

Warm Primaries (Left) Cool Primaries (Right)

The warm primaries make some wonderful oranges, but the greens are very dull and the purples almost non-existent. The warm red and the warm blue has almost neutralized each other completely. Which might actually be a good thing, if you want to mix browns and greys.

The cool primaries, on the other hand, makes some brilliant greens, and lovely shades of purple. It still gives you some good oranges, but if this was an even cooler yellow, you’d get even duller and weaker oranges.

Split primary color mixing

Split Primaries

Now on to the good parts. The whole point of this split primary theory is that you can supposedly achieve brighter secondary colors by mixing the primaries that lean toward each other. A warm yellow and a warm red will produce a clear orange, since they are both on the orange side anyway. They don’t contain any blue at all, like a lime yellow and a magenta red does. And we all know that yellow+red+blue = brown, or mud. The clearest greens would come from a cool yellow mixed with a cool blue, none of which contain any red at all to dull down the mix.

If we were to put all of this together in one color circle, we’d have to split the primary spots into two, and mix each color with the primary closest to it. The color circle below has a whole new dimension of deep and brilliant colors that you probably wouldn’t be able to easily achieve using only three primaries.

My personal favorite mixing trio

Ilse's personal favorite mixing trio

But I also want to show you an alternative to this six-color palette of warm and cool primaries, that takes us back to the original primary color theory. My personal favorite of primaries is a combination of the following three colors:

  • The cool yellow we’ve already looked at. To me this is the perfect primary yellow. In my eyes it does not lean towards neither red nor blue, and therefore it creates both oranges and greens that are clear and vibrant.

  • The cool blue from before. Even if it is a turquoise shade, you’ve seen that this blue can give you pretty good purples in addition to vibrant greens.

  • A rose red. Warmer and softer than the vibrant magenta, but cooler than the warm red. This middle-of-the-road rosy red will mix wonderful purples in addition to warmer oranges.

You can see the whole rainbow of colors I got from this trio in this pretty color circle!


The paints used in this post are:

  • Cool yellow: Winsor Yellow by Winsor and Newton, made with pigment PY154

  • Warm yellow: Yellow Orange by Schmincke made with pigment PY153

  • Cool red: Quinacridone Magenta by Winsor and Newton, made with pigment PR122

  • Warm red: Cadmium Red Light by Schmincke, made with pigment PR108

  • Rose red: Quinacridone Rose by Daniel Smith, made with pigment PV19

  • Cool blue: Phthalo Turquoise by Winsor and Newton, made with pigment PB16

  • Warm blue: French Ultramarine by Winsor and Newton, made with pigment PB29

You do not have to get these exact colors to achieve the different shades in the color wheels. But keeping in mind that there are different versions of primary colors that have different properties will make it easier to find paint that suits your needs.

My main tip is to look for paints made of single pigments that are rated with high light-fastness (to avoid fading in daylight). Also: The pigments listed will often go by different color names in the different paint brands’ collections. So you can look for these pigment codes within other brands if you want to get these exact colors from your favorite brand of watercolor.

If this talk about pigments and paint properties is confusing you – don’t worry! I have a whole post planned about this subject, so stay tuned and I will enlighten you! Hopefully you’ll be left with a good idea of what paints and colors will suit your needs, without getting the entire Winsor and Newton catalogue worth of colors (since that is a very expensive approach to filling your color needs..). Stacey and I will also work on bringing you perfectly good alternatives of handmade watercolors to fill your tin, without ever compromising on quality, colors, vibrancy or smoothness!

Until then:

Lots of colorful love,


Note: The colors in the pictures may differ from their originals, based of the quality of my scans, and the screen settings on your computer/phone/tablet etc.

Color Wheel Template Links

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Theresa J: There is actually an ongoing discussion on how to properly name blues. "Warm" and "cool" are just the human made-up words for "closer to yellow (or orange)" on the color spectrum, because we associate yellow, orange and red with warmth. Whereas magenta and blue seem cooler. Based on this we should actually say that a yellowish blue is in fact "warmer" than for example an ultramarine. But a lot of people *feel* that blues leaning towards red are warmer 🤷‍♀️ So you're not wrong at all, and the case of the blues is not quite settled! Also, you explain how it makes sense to you beautifully so please continue to describe colors! 😁 Ilse


Theresa J
Theresa J
Feb 09, 2020

Thank you so much for sharing! This is such an easy to understand guide on basic color theory. I, personally, am TERRIBLE, and have it all backwards in my head when it comes to blues. Because a "cool" blue doesn't feel cool at all! It feels warm and vibrant and tropical. And a "warm" ultramarine feels frosty and wintery. So in my head, warm is cool, and cool is warm, and I should never be allowed to write color descriptions. If that makes any sense at all, haha.


This is so fascinating! Thank you for sharing your knowledge and passion for color! I can’t wait to creat one!


Ilse, this post is great!!! A lot of great info, and a perfect introduction into color mixing! Many posts explain the difference between warm and cool colors, but do not give examples of 3 colors that would work perfectly together. Thank you for that. Can't wait to read your take on pigment info!


Thank you so much for sharing your knowledge. It's so easy to accumulate a huge stash of wonderful paints and then feel a little overwhelmed about which to put together! This is such a clear, well written explanation of split primary theory!

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