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Tuesday, October 18, 2005

Urban Myth: Blue and Yellow Don't Make Green

Have you fallen for that one? If so, you probably don't mix greens but use tube greens like phthalo, Hooker's or sap green instead to be on the safe side. It's likely that your greens all look pretty much the same and are somewhat unnatural-looking. No matter what your subject matter, if you paint realistically you want your greens to have the variety you see in nature.

Let's debunk the myth about blue and yellow. There are innumerable beautiful pigment variations of these two colors that will make every green you can possibly imagine. A simple rule of color theory will help you mix the green you want: When mixing a secondary color (green) from two primaries (blue and yellow), avoid the third primary (red), which is the complement (opposite) of the secondary mixture (green).

For example, to mix bright greens use cool pigments: phthalo blue and cadmium lemon or Winsor Lemon. To mix low-intensity natural greens, use ultramarine and any warm yellow, such as New Gamboge, cadmium yellow medium or Indian yellow, which all have a hint of red that knocks the intensity down a bit.

If you still like to use tube greens occasionally, tone them down by mixing with any color that has a reddish cast, such as burnt sienna, or a touch of alizarin crimson or cadmium red.

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15 Comments:

Anonymous Bernard said...

Have you told all this to Michael Wilcox?

7:53 PM  
Blogger Nita said...

Why would I do that?

8:11 PM  
Anonymous Anonymous said...

Not quite.

Red Yellow and Blue are simply NOT primary colors!

http://en.wikipedia.org/wiki/Primary_colors

"Using red, yellow, and blue as primaries yields a relatively small gamut, in which, among other problems, colorful greens, cyans, and magentas are impossible to mix, because red, yellow, and blue are not well-spaced around a perceptually uniform color wheel."


Our eyes have 3 cones: one whose response curve peaks around red, one whose peaks around green, and one whose peaks around blue (this is simplified.) RGB are the *additive* primary colors.

The subtractive primary colors -- or pigment primary colors for paints and inks -- are Cyan Magenta and Yellow, and they do a far better job of being primary colors, because Cyan is the true opposite of Red, and is basically red-absorbing, Magenta is green-absorbing, and Yellow is blue-absorbing. This is why when you mix all three together, you get something close to black or grey. (Whereas when you mix red, yellow and blue, you get more of a brown -- because red is magenta/yellow, and blue is cyan/magenta -- so you get an extra dose of yellow and an extra dose of magenta, which make the "black" more orangey.)

The reason why mixing "blue and yellow don't make green" is because blue *pigments* act like magenta and cyan mixed together -- try it: go mix magenta and cyan paints in equal parts, and you will get blue!

You can also mix magenta and yellow and get red -- which means red is NOT a primary color, by definition.

Often, "blue" pigments are really cyan -- our eyes respond far less to blue, and so distinguishing differences is physically difficult. Also, culturally we lump blue and cyan together, which makes it even more difficult for us to distinguish.

I am a computer scientist and once worked on a color printer driver -- converting what's on the screen (RGB) to a print (CMY) -- and that was when I learned that I had been wrong all those years! Since then, I have an intense interest in light, pigments, and how the eye actually works.

It took me many years of playing with light myself -- LEDs and neon artwork -- to really believe it myself!

It will be very hard for artists here to believe it too, but it's true. You cannot argue with science. This is how our eyes *work*.


Here are some experiments to try to convince yourself:

Mix red and blue: you get a dull purple *at best*, brown or grey is more typical (depending if the "blue" is more cyan, and the "red" is more magenta.)

Mix 2 parts magenta, 1 part cyan for a far more vibrant purple.

Mix equal parts yellow and magenta: you get red!


Test your eyes:
Stare at something very red in good light for 1 minute. Now look at a piece of paper. You will see cyan not green (again, depending on if the "red" is more magenta.)

The reason this works is because the red cones will "tire" and but the green and blue cones are raring to go! This shows the link between colors and how our eye *actually* works.

Green -> Magenta, not red
Yellow -> Blue

Shine a red LED and a green LED together -- you will get yellow. (Depending on how blue the green is -- I had a green that had so much blue, I got white when I mixed them!)

Shine red and blue LEDs and you will get magenta.

Shine blue and green LEDs and you get cyan.

This shows the *direct inverse* relationship between the additive and subtractive primary colors.

You can also take a look at this:
http://burningideas.com/colorspace/pics/000228-Table_photos/Kiki/rgb.jpg

This is a piece of neon artwork I made: there are only 3 neon tubes: red, green and blue. When the triangular pyramid *faces* the tubes, you see RGB, when you turn it 1/3 of a turn, you mix the lights and produce CMY. Again, this shows the *direct inverse* relationship between the two primary sets.


My theory why Red, Yellow and Blue are purpetuated is that historically there was no magenta pigment. Artists 500 years ago could buy red, yellow and blue paints and get a decent pallet of colors, without buying more than that.

This is my own theory, but I don't see why it's not true. I can't think of an old painting that has magenta in it -- or a vibrant purple for that matter.

But if *you* want to buy only 3 colors, buy Cyan, Magenta and Yellow instead, and you'll find you can mix far more colors than Red, Yellow and Blue!


Sorry to be so wordy. It is my pet-peeve that red, yellow and blue are still perpetuated as primary colors.


Hope that makes things clear.



And if that weren't enough for you, did you know magenta is a phantom color? It does not exist in the spectrum -- take a look at a rainbow and you won't find magenta! It fades from red to IR at one end, and purple, violet then UV at the other end! This is because there is no pure frequency of light that can stmulate the red and blue cones without stimulating the green cone.

1:53 PM  
Anonymous Nita said...

Thanks for your learned dissertation. I notice that you don't mention pigment names, but reference light and computers. For painters, it all comes down to which red paint, which blue paint and which yellow paint you choose. There are no spectral colors in paint, so the rules of light don't work so well. I agree that permanent magenta (if it's the right one), phthalo blue green shade and a balanced yellow (if it's the right one) are a nice primary group. However, magenta is too blue to mix a good orange with any yellow, so there are limitations there, too. But my preference over all is a six-primary palette including those three, plus cadmium or pyrolle red, a cool and a warm yellow, and French ultramarine blue.

2:36 PM  
Anonymous Anonymous said...

(same anonymous person)

I disagree! I am also a painter.

There is nothing at all magical about paints over inks or computer graphics. It has to do with our eyes, not any chemicals or how thick or runny or transparent or opaque the paint or inks are.

Go buy tubes of magenta, cyan and yellow -- cyan is *not* blue -- and try mixing them. You will get a far greater gamut of colors than any red/blue/yellow combo.

There is no difference between your paints or a color printer. If you get good representations of the subtractive primaries (printers add black ink), you could essentially mix colors as well as a printer or a color photograph.

It has to do with how our *eyes* work. Not paints or inks or lights.

(Somehow painters seem to be unable to let go of red/blue/yellow.)

2:51 PM  
Blogger Nita said...

A prominent opthalmologist once told me that science hasn't a clue what colors each person actually sees. What colors work for one person may not work for another. So I maintain my position of offering both primary options so artists can find the combination that most appeals to them. To say that one set of primaries is the absolutely correct one over another set is ridiculous. There are no perfect primaries, nor are there perfect mixtures. It's all about the preferences of the individual artist. Using the split primaries is merely a way to help artists to gain more control over color mixing and understand the theory of mixing complements to lower color intensity. Of course, you no doubt disagree with me on this, too, but then, that's your primary purpose. (Sorry, couldn't help myself.)

6:18 PM  
Anonymous Anonymous said...

Actually, Nita, you and Wilcox are in almost perfect alignment. All he says is

1) blue and yellow only make Green because they both contain green as a common component, not because blue and yellow inherently make green.

2) To mix a vibrant green, choose yellows and blues with a lot of green in common.

3) To mix more subdued greens, choose either a yellow or a blue containing little green.

4) To mix the most subdued green of all, choose both a yellow and a blue containing little green.

That's pretty much the whole book: the concept of split primaries.

5:19 AM  
Anonymous Anonymous said...

so heres my dilema. i hyave a soft yelow and i keep making a soft leafy green. PLEASE HELP!! its for an assignment due soon!

7:18 PM  
Anonymous Anonymous said...

HELP!!!!!!!!!!!!!!!!

7:20 PM  
Blogger Nita said...

Since you didn't say what type of green you want to mix, I can't be of much help. The answer to your question is in the original post above. "to mix bright greens use cool pigments: phthalo blue and cadmium lemon or Winsor Lemon. To mix low-intensity natural greens, use ultramarine and any warm yellow, such as New Gamboge, cadmium yellow medium or Indian yellow, which all have a hint of red that knocks the intensity down a bit."

7:42 PM  
Blogger mad4color said...

I got into this discussion very late. I like to paint with PY3 hansa lemon, PV19 quinacridone red, and ultramarine blue. I usually throw in a pthaloycanine green for a better cyan mix with the ultramarine.

I prefer ultramarine blue to pthalocyanine blue. So I mix a cyan from ultra blue and pthalo green.

The mixed red or orange I get from lemon yellow and violet red is usually fine for me.

But, I understand why people like Nita prefer split primaries. Bruce MacEvoy says it best; artists mix paint, not color.

I prefer transparent and dislike the opaque cadmiums. Pyrrol red is opaque too.

It's not just about the color. Other qualities manifest with different paint choices: opacity, texture, tinting strength, etc. Hilary Page shows how different pigments reflect light across the spectrum and why some are better mixers than others.

My version of a red or orange does not tend to be very opaque. I also like to make my mixtures a little more opaque or heavier by mixing in earth colors.

None of us see color the same.

1:36 AM  
Blogger mad4color said...

I inadvertently proved this to myself this weekend. I don't care for the opaque cadmium orangy reds and am not that fond of pyrrol either. Opacity must make the red more intense to me.

I found out that I have had the perfect orangy red myself for years. I have a huge stash of Liquitex watercolors that are no longer made that I got very cheap, including lots of vermilion, which I knew was transparent.

I got out the vermilion again; the pigment red is PR209, which other watercolor manufacturers started utilizing much later.

Now I am going to experiment with mixing the Liquitex vermilion with some earths for an acceptable more opaque red.

I painted out several large vermilion patches on a virgin sheet of paper. I have the lovelies glowing orangy transparent color with bluish undertones.

There is no way I can make a red orange this transparent and glowing from my mixes. I can come close to the hue, but it won't be the same.

Particle size and other factors, like clay in the earth colors, all affect the way we see color. Ink reproductions can't pick it all up.

I also reread some stuff on Don Jusko's history of pigment sites. I like his discussions of transparency and opacity.

I

3:21 AM  
Blogger Dain Q. Gore said...

Interesting points. I would add the following:

There's no such thing as a perfect color, only the color that is perfect to you. That's qualia in a nutshell. Saying "Green" without a specific hue profiles is like saying something is "Spicy." It's essentially a neutral term until someone experiences it.

Paint or pigment, or any sort of color replication that doesn't use pure light is what happens when color theory meets physical reality. There are bound to be disputes over the purity of the result.

Any discussion on mixing with light is interesting and academic from a scientific angle, but not necessarily possible from a practical one; unless, of course, you are using light as your media.

@Mad4Color: Indeed! I think translucency and opacity, along with warm and cool undertone/masstone, are the keys to learning how to paint. Everything else is pretty much just how you handle the brush, how thick you want to apply your paint, and what you want to depict. Everyone can and will get the green *they* want when they become aware of these things.

5:33 PM  
Anonymous Anonymous said...

who is michael wilcox

8:00 AM  
Blogger Nita said...

Michael Wilcox is the author of "Blue and Yellow Don't Make Green."

9:51 AM  

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