Pop Go the Pigments

Remember how it was back in high school when you’d come to class and the teacher would “pop” a quiz at you from out of nowhere? I was a good student, so I never worried much about little surprises like that, but many classmates thought it was quite unfair to be given an unexpected test.

This morning I gave myself a little pop quiz on pigments, and I’m pleased to say that I got all the answers right, but not without a lot of thought. I was only completely confident on a few, but fairly certain on most. Here’s what my little quiz was all about: color temperatures of the pigments in my new “Cotman Pocket Set“.

Even though I’d intended to start playing with the set a few days ago, I haven’t yet gotten around to it. Too many other things going on. So, my half-pans of pigment are still sitting there, neatly wrapped, ready to be opened and used. Here’s a look at how they’re packaged.

Cute, aren’t they? I love that I can purchase single pigments this way. It allows me to create my own “Pocket Set” with the colors I use most often. Of course, if I continue studying watercolor technique, I’ll probably purchase a larger palette, one that can hold far more than the 12 half-pans in my “pocket” paint set.

But, I digress.

Since I hadn’t yet opened any of these pigments, I could move them around if I wanted, and I decided, yes, I wanted to re-arrange them a bit. How about placing all my cool pigments on the top row and the warmer pigments on the bottom row? I liked that idea, so I literally “popped” the pigments out and spread them across the table.

Now, the fun could begin. Surprise, surprise! Did I really know which pigments were which? Well, what a nice little quiz I’d just presented myself with. I approached with confidence, quickly putting lemon yellow and alizarin crimson in their proper places, and the cadmiums — yellow and red — fell into place then, too, of course.

Most of the time, it is fairly easy to see color temperature in my pigments. As long as we can recognize the color bias we can neatly divide our primaries into relatively cooler or warmer temperature classifications. At least, that’s true for the reds and yellows.

Blues are not so simple, and in my pop quiz, I was faced with phthalo blue and ultramarine. Which went where? I use a lot of ultramarine in my painting and felt fairly sure it was a cool temperature, so that’s where I placed it. But maybe I’m wrong here. A bit of browsing online reveals a lot of disagreement on ultramarine blue. Some artists and paint manufacturers swear by its warmth — including my most-used reference sheet — while others see it as cool, or, at least, as cooler than phthalo blue. A case could be made either way, I suppose, and when it comes to blues, it’s tricky since all blues have a slight warmth. For my part, I’ve decided to call ultramarine a cool blue, even though as recently as last week I was placing it with my warmer pigments. It’s all relative, remember? So, my ultramarine is warmer than my Prussian blue, yet cooler than my phthalo blue. That’s how I see these pigments. In other words, when asked “Is ultramarine warm or cool?” the only correct answer is “It depends.”

Next came two green hues. I had viridian — oh, yes, remember viridian? — and I had sap green, which happens to be a favorite of mine. At first I put sap green on the cool side, but then I thought back to the day I spent painting with viridian. Nope. Viridian is not a warm green. I transposed the pigments and put them into what turned out to be the correct places. Viridian is indeed cool; sap green is warmer.

So far, so good. A bit of doubt here and there, but in the end, I had my primaries and my green pigments all neatly ordered.

What now? Earth colors, and here’s where I felt most challenged. I had white — which I consider to be cool — so, there’s that. I also had yellow ochre, burnt sienna, and burnt umber. Obviously those “burnt” colors would be warm pigments, so I was left to ponder yellow ochre. Was it also warm? Or could it be cool? Having used yellow ochre often in my landscapes, I sensed its warmth.

So, my Cotman palette now holds the following colors in the following order:

Alizarin Crimson, Lemon Yellow, Ultramarine, Viridian, Chinese White (All cool) and Burnt Umber.

Cadmium Red, Cadmium Yellow, Phthalo Blue, Sap Green, Yellow Ochre, and Burnt Sienna (All warm).

Although I was correct in assigning temperatures to my pigments, this exercise left me with a few questions:

  • Are there any “earth tones” that are on the cool side?
  • Are all umbers and siennas warm?
  • What about black?
  • Is there a warm white?

To help me answer those questions, I turned to one of my favorite online sources: Gamblin’s Color Temperature and Value List. From this I learned that the siennas are all warm earth tones, although there is cool transparent earth yellow, a  Gamblin pigment often used for glazing. I discovered that while burnt umber is warm, raw umber is considered cool. And while blacks on the list are not shown with any temperature, I do know that blacks can be mixed to lean toward either the cool side or the warm side. To my surprise, I did learn that Gamblin also makes a warm white. I learned early on in my oil painting, however, to avoid using pure white, so I always add a smidgen of another hue — thus creating either a warm or cool temperature, depending on what I think I need.

In the last few years, I have learned a lot about color theory, color mixing, color temperature, color bias. The next step for me in my development as an artist lies in learning how to put this knowledge to use. Last spring I did a lot of color studies and learned that while we need both warm and cool colors in our painting, one should be predominant. I remember learning that cool light means warm shadows and warm light means cool shadows. But there’s color temperature and then there’s pigment temperature, and I’ll need to do a lot more studying before I get it all sorted out in my head. Only then will I really be able to use that knowledge while painting.

There is so much to learn about color in painting, but at least I’m beginning to feel more sure of myself when it comes to seeing and understanding the color temperature of various pigments. And, if in doubt, I can always check Gamblin’s helpful list — which I’ve now printed out to keep for reference.

As part of my learning process, I’m going to put a notebook together where I can compile all of this color information. That will be a helpful addition to my art library. Even so, I know I’ll never have a complete mastery of color theory, but that’s all right. Learning is meant to be a lifelong process.



  1. I advise a test for whether your ultramarine is a warm blue or not: try to mix a vivid purple using alizarin and ultramarine. Then try using alizarin and pthalo blue. Which makes the best purple? Obviously, you would not get a satisfying purple by using a cadmium hue red with either blue, because cadmium has a yellow bias, but try it just so you have four real swatches to compare all your possible blue and red combinations. You clearly understand that you get muddy or grayish color any time you mix all three primaries, so try mixing any cool primary with any warm primary in your Cotman kit. You will find that lemon yellow plus (warm) ultramarine gives you muddy olive green, but lemon plus pthalo blue makes a clear green apple hue. Or a darker green, depending on the amount of pthalo blue used.
    Cotman colors are not the same quality as “real” Winsor and Newton paints because they use cheaper pigments, so your results may differ, but having your own color wheel mixed from the paints in your kit will teach you what to expect from them. Real French Ultramarine is made from lapis lazuli mined in Afghanistan, so not cheap! But even Cotman student grade ultramarine ought to behave like the real thing when mixrd with a cool red versus a warm red. Ultramarine is a warm blue, compared to pthalo blue. Try making purple, and don’t forget to label your color wheel experiments…. mixing is fun. Have fun getting to know your new paints! P.S. try to get bright orange from alizarin red and lemon yellow, and then try using cadmium hue with both yellows. Proof that alizarin has a blue bias and cadmium has a yellow/warm bias. And fun to learn!

    Liked by 1 person

    1. Color mixing can definitely be fun. I’ve been doing a lot of color mixing with my oils. I’ll be doing the same thing with my Cotman colors. Yes, student grade works fine for me since I’m really just having fun playing. I do have artist quality M. Graham watercolors if I want to get serious. 🙂 I really like the little “pocket set” though because it’s so easy to take to art club meetings. Thanks for all the helpful suggestions. 🙂


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