“The Greatest Show on Earth,” by Mark Kevin Gonzales, oil on Gessobord, 12 x 9 in.

Particularly in plein air painting, where carrying a lot of paint tubes around and having a complex palette is often avoided, artists go for a split-primary palette, with a warm and cool for each primary color. So what is your warm blue?

Many people would name ultramarine blue. But when Mark Kevin Gonzales was asked by a student at the Art Students League of New York if ultramarine is indeed a warm blue, he fell down a very strange rabbit hole.

“I had no idea about this debate until last week,” says Gonzales. “A student here said she had seen on Gamblin Artist’s Colors’ website that ultramarine blue was a warm blue. She was surprised because she has always thought it was a cool color. She even asked her teacher here at the Art Students League, and he agrees with her that it is cool. I was surprised and wondered how many other artists thought. So I started asking students and teachers their ideas on the matter. And I was surprised at some of the results.”

“Wallowa Sunrise,” by Scott Gellatly, 2014, oil on panel, 12 x 12 in.
“Wallowa Sunrise,” by Scott Gellatly, 2014, oil on panel, 12 x 12 in.

Just counting teachers, Gonzales scores it at 20 to 10 votes, with the warm contingent winning. But if that many professional art instructors feel differently, there must be more here than just a black-and-white answer. We asked Scott Gellatly, the product manager for Gamblin, to help explain what might be going on.

“The ‘coolest’ spot on the color wheel is a middle blue (i.e., cobalt blue),” Gellatly asserts. “Once you move around the perimeter of the color wheel from this point, colors get warmer — as you move toward either red or yellow. So, ultramarine blue is warmer (more violet), as is manganese blue (more green). Across the ‘coolest’ spot on the color wheel is the ‘warmest’ spot, being a middle orange. Hence, adding orange to blue not only lowers the chroma, but makes it warmer as well.”

Gellatly adds, “Ultramarine blue is indispensable for skies, water, and atmosphere.”

Gonzales came to the same conclusion, and applied a bit of psychology to the issue, as well.

“What I think is that the two schools of thought about blue separate like this: The people who see ultramarine blue as cool have a yellow bias, and the people who think ultramarine blue is warm have a red bias,” Gonzales says. “Some argue that as blue goes toward green it is closer to the warm colors, closer to yellow. And almost all of those who said ultramarine blue is warm say there is red in it, so they have a red bias. The warm ultramarine blue people believe that the blues toward green are cooler and the cool ultramarine blue people think the blues with less yellow are cooler.

“vroom,” by Mark Kevin Gonzales, oil on linen mounted on board, 5 x 5 in.
“vroom,” by Mark Kevin Gonzales, oil on linen mounted on board, 5 x 5 in.

“So for the cool side, cobalt is warmer than ultramarine blue, and cerulean is warmer than cobalt, and vice versa for the warm ultramarine blue people. A few of the landscape painters say the cool colors recede, and ultramarine blue recedes more than a color closer to yellow. However, one landscape painter says cool greens recede more than reddish blues. He also said he thinks of blues as red-blues and yellow-blues.”

Gonzales continues, “The warm ultramarine blue people also say it is an emotional response to color. In my mind I think of how in cartoons when a character got angry, he turned red. Red is associated with quite a number of things, from love to violence. And when I think of cool, I think icebergs and glaciers. And in my mind — though it might not be true— as light would go through a glacier, it looks like a blue green color. On the light spectrum red has the longest wavelength and violet has the shortest, but as I have said, warm and cool in terms of color is an emotional response to color, not scientific. Most of the teachers I talked to are stunned that there are two views on ultramarine blue. I’m a warm ultramarine blue guy, but I can see the other side’s point of view, and I will never look at blue the same way again.”

There you are. It’s as clear as the blue sky.

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  1. I could be wrong but i have always believed there are two types of this pigment: regular ‘Ultramarine’ and ‘French Ultramarine’ which leans to Red. I think the thing to always keep in mind is that there are no absolutes in colour– everything is relative to what it is next to so we have to see colur in context when making colour choices in painting.

  2. For those who consider ultramarine blue warm, then what is a cool blue pigment? Manganese blue, Prussian Blue, and Cobalt are all considered warmer than Ultramarine, so by process of elimination, ultramarine blue has to be cool.

    • Bob nailed it – there are two schools, neither is right or wrong. To me, being a red is warmer than yellow type, Ultramarine is warmer than Manganese, Prussian and Cobalt. For those on the yellow side of the fence, Ultramarine would be cooler. The important thing is how we use our ideas in painting. As long as neither throws off our color temp relationships we’re in good shape!

  3. For more than twenty years I believed Ultramarine Blue was cool but eventually changed my mind after a student asked me about it three years ago and I did my own research. I first discovered there are reputable art books out there with conflicting opinions…no help…and with respect to the above mentioned findings in this article, I did my own research in nature and came to a simple conclusion; If you stand outside on a clear day and look straight up at the cooler air of the Zenith, it is clearly Ultramarine blue. As you make your gaze slowly down towards the warmer air of the horizon, you’ll find it gets more in the Cerulean Blue range until ultimately you find your gaze on the horizon itself where even warmer light (pastel like yellows and oranges) is present. This is light bouncing off the earth and back into the atmosphere at the horizon, warming it.. In my view, this is a clear range of cooler air and color at the Zenith progressing downward to warmer air and color at the horizon. Even though the Zenith is closer to the sun than the earth, because of air pressure, volume and energy, it is warmer at the earths horizon….Its complicated but google it…or to simplify, the air is always cooler at the top of a mountain than air at sea level despite the top of the mountain being closer to the sun. For landscape painters, I refer to my findings which were calculated while observing nature…truth.

    • This really supports my belief that Ultramarine blue is cool. It makes the most senses when explaining warms and cools. My own reasoning is this, I always thought that because ultramarine mixes with Alizarin crimson to make purple and Alizarin is a cool red. A blue purple which has more ultramarine in it is a cool purple. Thank you.

      • Man.. That is a really good point. Bc I’m of those that sees ulta blue as warm. Never thought of it as cool and I think regardless my eyes will see it as warm. Even though even the name ultra – marine – ocean… Would point to cool with that alone, this explanation made me gasp lol! Really good point! True to the article, will likely see warm but never really SEE blue the same way again. Lol. Thank you.

  4. Before learning anything about color temperature (and I am still learning), I believed I had picked up all cool primaries in my first watercolor class-which included Ultramarine Blue. Then I watched a youtube painter call Ultramarine Blue ‘warm’ and it’s sent me on a goose chase. So now, I call my Ultramarine Blue warm for color mixing exercises, but I’ve also come to think of my Cobalt as cooler and my Prussian blue as warmer due to those same exercises. But if my Ultramarine Blue was to be the warm compliment to Cobalt, then Cobalt must be cool instead of warm? GAH. The more I think I understand…. Do I even have a stand alone cool blue?!!

  5. Good article, when you think about it, anything you do to blue will warm it. So I agree with Gonzales, it’s mostly an emotional response. In some painting situations either could appear warmer or cooler depending on how they are used. Fun discussion!

  6. I am perplexed that this is even a debate. To say any colour is warm or cool is only meaningful when it is placed in context of other colours next to it. Colour shapes are rarely seen in isolation except in maybe abstract colour field paintings. Whether a particular colour appears warm or cool is wholly dependent on its relationship to other colours in the same painting.

  7. Forgive me, but this this is damned nonsense. Get a Munsell chart and have a look; these questions were answered long ago. There is no reason to talk about red or yellow bias. “Warm and Cool” are relative terms and should only be used as shorthand to describe a color’s relationship to another, or to a painting’s over-all scheme. Simplify your life with hue, value and chroma, for crying out loud, and flush “temperature” down the toilet where it belongs.

  8. Further on the cool side of the discussion…as you move around the color wheel from warmer yellower blues like cerulean, when you hit redder blues like ultramarine you are on the coolest side of the reds (magenta) and as you proceed you get to the warmer hot reds closer to orange. In my mind, the yellower side of orange feels hottest, and the violet side of blue feels coolest. I don’t know if science has defined optical “peaks” for warm and cool, but am certainly interested. Nice article, thank you!

  9. Er….sorry, Erik, and all other art lovers, for my robust outburst. But I find it utterly pointless to use ‘wavelength” when discussing color. We do not need to know that violet has the shortest wavelength,(and is thus “cool”???!!??) and red the longest. What we need to understand when determining a paint color is, “redder, blue-er, yellow-er,” or “more chromatic, less chromatic” and so on, based not on an isolated spectral reading, but on our available PIGMENTS. If you stack up the available blue PAINT on the market, it is easy to agree where one is leaning violet , and where the others are leaning green, and where others are less chromatic. And this has noting to do with what a particular manufacturer thinks about “their” version of a color ( where there is great variation) ; mix up a tint, and stick it alongside other versions of the color, and ask those simple questions. That as all ye need to know on earth.

    This is why “warm” and “cool” need to be ditched when looking at available paints all by themselves. It is only useful in a relative sense — to adjacent colors or over-all schemes, and even there it is often a lazy expression. When you say a gray is “warmer,” why not try to be more precise and say it’s “orange-er” or “red-er”? Keep things simple– is the blue a purple-er blue, or a greener blue? It’s easy!

    Where is Graydon Parrish when we seriously need him?

    And finally, brethren, “cool colors recede” needs a serious overhaul too, but now I must go to my lonely easel and not think about this any more, lest I need a big glass of wine.

  10. At the risk of sounding a little polemic, there is no such thing as an innately warm or cool hue. Despite what some people may believe or have been taught, color temperature is not tied to a specific hue. It is established by the relationship between two (or more hues). Or, to be more precise, where the hues sit on the color wheel. Ultramarine can and will be perceive as being the cooler hue if it is placed next to a blue-green (a blue + a little yellow). Whereas if the same Ultramarine is placed next to a violet (a blue + a little red, but no yellow) it will be perceived as warmer than that violet. This is the Yellow/Purple Warm/Cool temperature model developed by the French Impressionists, a model based upon the observations they made while painting neutral subjects such as white clothing and snow in direct sun. Of course, we are talking about recreating the effects of light with paint, and the subsequent subtractive light by which we see the painting, so that further complicates any explanation…

    To digress even further, Sorolla once said this about the French Impressionists: “With all its excesses, the modern impressionistic movement has given us one discovery, the color violet. It is the only discovery of importance in the art world since Velazquez.”

    I just posted a lengthy post on my blog about this very subject, if anyone wants to read it…

  11. You began this article by discussing the desire of plein air artists to limit the number of tubes of paint when traveling into the field. To do so, many set up a palette of warm and cool versions of each primary. With that in mind, this may help: An artist who views the primaries as Red, Yellow, and Blue will typically have a Cad Red Medium, Cad Yellow Light and Ultramarine Blue (or similar) as their base set. With this view, the warmest color is the orange between the red and yellow, and the coolest color is its opposite, or the third primary – Ultramarine. However, a painter who works with the Cyan, Magenta, Yellow primary philosophy will find that the secondaries are Red, Green and Blue – thus making a warm orange-red and a very violet-blue their secondary colors. With this model, the paints that will work for a good field kit include the primaries of Cyan (Phthalocyanine Blue-Green Shade – PB15:4), Magenta (most consistently purchased as Quinacridone Rose – PV19), and Cadmium Yellow Lemon. For a dual primary palette, add Cadmium Red Light (a very warm orange-red and the warmest color on this palette which is the complement of cyan blue which is the coldest. Think ‘ice’ blue), Ultramarine (a “warm” red-blue to go with the coldest color on this palette – cyan blue – which is not yellow, it simply has NO red in it), and Cadmium Yellow Medium or deep (depending on the manufacturer) which will give you a nice orange yellow. The addition of Burnt Umber will allow the mixing of of a wonderful range of warm and cool grays when combined with Ultramarine Blue and Titanium White for a field set of 8 tubes of paint. For beginners wanting an introduction to basic color mixing theory, they can check out my book: Color Mixing, “Color Matching – How to mix clean bright colors and beautiful neutrals,” which is for sale through Amazon.

  12. John Bosquet-Morra hits it on the head for me … it’s all relative! A favorite art teacher of mine, who has written a book on color theory, drummed into us what she called “The Rule of ER” … blue, red, yellow, doesn’t matter as the same principle applies to every hue. When two colors of the same pigment are placed side by side, one color is warmER than the other and one color is coolER than the other. The same is true of light and dark: one is lightER and the other is darkER. Compared to each other. But when you introduce a new color the whole relationship changes. Simply The Rule of ER.

  13. Perhaps it is considered wrong to go by Nature itself, but as soars towards outer space, the temperature drops. As one goes deeper in the ocean, it gets colder. Observing the sky, the higher I look, the more ultramarizne blue it appears to me. The shallow areas of the ocean look much more cerrulean, and as the ocean deepens, I see it turn more to ultramarine Blue. That’s what I see.

    However, I have noted in past years that the English seem to call ultramarine Blue warm, and I have no clue what color they call cool blue, perhaps Cobalt. Somehow that seems to work for them. I suspect consistency is the key.

  14. It’s all relative…relative to any other blues in the piece, relative to all the other colors in the piece, relative to the piece as a whole. And even relative to the individual’s preference. Does that about cover it? LOL!

  15. My sensibilities lean toward a yellow orange (warmest) -violet blue (coolest). I agree mostly with the folks that say “color environment (or tonal environment) affects how the color in question is perceived. When I was designing posters in the 60s, I used color as energy – juxtaposing equal density colors next to each other to affect a visible buzz which is an effect of the rods & cones in the observer’s eye. At the same time I would use warm colors to pop forward & cool colors to recede. The op artists of the 50’s & 60’s made an art form of these dynamics. Josef Albers made it a science. The best approach is that of observation. How do certain colors in a piece of artwork feel. It is all relative and subjective.

  16. Here is a thought. I have always believed in making up tinting charts in order to learn as much as possible about the characteristics of a given colour. Before leaving the issue of whether French Ultramarine is visually a warm or cool blue, let’s just ask the same questions of Kings Blue. A straw poll among artist friends gained a universal vote for cool. Very interesting as several also thought French Ultra was warm.
    But hang on a minute, Kings Blue is a mixture of French Ultramarine, Titanium White and Zinc White so is a tint of French Ultramarine!

  17. I have enjoyed this conversation! I agree it is about relationships more than anything else. But, if I want a warm and cool of each primary, mine are Thalo Blue (coolER), Ultramarine Blue (warmER), Alizarin Crimson (coolER), Cad. Red Med. (warmER), Cad. Lemon Yellow (coolER) and Cad. Yellow Medium (warmER). No one even mentioned the Thalo Blue in the above conversation… I see it as a greener blue, and the Ultramarine as a redder blue.

    I also loved someone’s comment about the grey issue … I talk all the time about is it “say it’s “orange-er” or “red-er” or green-er!” There is no grey in my eyes!

    And someone said to ditch the temperature stuff…. I actually use it almost as much as value when creating effects in my paintings. And, I have heard this is “pure bunk!” But, guess what, not to my eyes! Have fun!

  18. This is certainly a controversial topic…Apparently I have a yellow bias (whatever that means).
    Obviously the temperature of blue is not something painters can agree upon.
    I do think of Cobalt Blue as the Perfect Blue, neither warm nor cool. To me the fact that Ultramarine mixes with Alizarin to make purple, makes it a cool color.
    In my own opinion, of course. 😉


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