Color Mixing in the Modern Color Gamut
My quest to learn to mix colors was long and frustrating.  Typically, artists are not scientists and much of the information published is confusing or down right wrong!  For instance there is a whole painting school that says ultramarine blue is a cool blue, while many others consider it a warm blue!  Further, everyone develops their own favorite set of colors and gives advice based on that set.  Following these various sources of information (or misinformation), I bought more and more tubes of colors looking for the right set.

Finally, the following three things happened that demystified color choice and mixing for me!
I strongly recommend the above documentation to everyone.  I will be describing in the following sections, how I have combined pieces from each of the above sources and added a bit of my own to define my new approach to color management.  I hope you find it helpful.
As described under the Pallet Layout Section, my pallet is an expansion of the Golden OPEN Modern Paint Set.  The basic Golden OPEN Modern Paint Set consists of seven relatively high chroma, transparent, organic pigments (which produce very clean mixtures), plus titanium white. For my new pallet I have also added zinc white which is transparent and can lighten the value of colors without changing the hue, bone black which is reasonable transparent and has a moderately low chroma and can be used to lower the value of paint mixtures with a minimum impact on the hue of the mixture, and carbon black which is an opaque color.  Titanium white and zinc white are my tinting colors, and carbon black and bone black are my shading colors.
Before going into the details of color mixing, I want to wet your appetite by sharing an example of one of my recent paintings, which is an homage to J L Gerome, Bashi-Bazouk, pictured below.
Remember the modern color set is composed of high chroma, "bright", colors.  It contains no subdued earth colors of the old classic type.  None the less my relatively subdued Bashi painting was achieved using only the three bright colors in the top of the chart pictured below, with just a bit of the darker red at the bottom thrown in!  This was accomplished using the relatively simple color mixing strategies that I will describe in this section.  I hope this sounds interesting, so let's get started.
As mentioned above, my augmented Golden modern color pallet consists of seven mixing colors, and four tinting and shading colors. 

The Golden modern pallet paint set includes a warm and a cool versions of each of, the blue, red and yellow hues, as well as a green hue. Another useful way of looking at the Modern Color Set is in the framework of Michael Wilcox's book, "Blue and Yellow don't make Green."  This is a great book which explains what actually makes color mixing work.  

Basically, white light has a spectrum of all colors.  Blue pigments look blue because they absorb all of the colors in the light except blue, which it reflects back to the viewer.  Similarly, yellow pigments absorb all of the colors of the light except the yellow, which it reflect back to the viewer.  Therefore, if you mixed pure blue and pure yellow pigments, the blue would absorb the yellow and the yellow would absorb the blue and the mixture would look black!!!  

The reason that blue paint and yellow paint can mix a green is that, in reality, the blue pigment contains some green and the yellow pigment contains some green.  When the two are mixed together all the colors are absorbed, except the greens that they have in common.  Therefore, if you want to mix a strong green, you must pick a yellow that has a large green content and a blue that contains a large green content.  In the case of our modern pallet, to get a strong green we would mix our blue with a lot of green, Phthalo Blue (Green Shade), and our yellow that has a large green content, Hansa Yellow Light. 

On the other hand, the Anthraquinone Blue and Hansa Yellow Medium paint pigments each have less green content.  Therefore, when these colors are mixed a weaker green will result.  We will demonstrate this in the context of the color wheel later in this post. 

Therefore, it its useful to consider two properties for each of our seven basic modern colors; the relative warm or cool properties of the paint, and the primary pigment content that will drive the mixing properties.  Therefore, for our pallet we have the following:

Hansa Yellow Light: a cool yellow with yellow and green (Y/G) pigments
Hansa Yellow Medium:  a warm yellow with yellow and orange (Y/O) pigments

Quinacridone Magenta: a cool red with red and violet (R/V) pigments
Naphthol Red Light: a warm red with red and orange (R/O) pigments

Phthalo Blue Green Shade: a cool blue with blue and green (B/G) pigments
Anthraquinone Blue: a warm blue with blue and violet (B/V) pigments

Phthalo Green Blue Shade:   a cool green with green and blue (G/B) pigments

This explains how to mix the strongest, highest chroma, secondary colors of  green, orange, and violet.  We get the strongest green by mixing the yellow/green color with the blue/green color  We get the strongest orange by mixing or yellow/orange color with the red/orange color.  We get the strongest violet by mixing the blue/violet color with the red/violet color.

The other mixtures will lead to duller, lower chroma, colors.  For example, mixing our blue/green color (Phthalo) with our red orange color (Naphthol Red Light) with give a very dull low chroma violet. because each color contains only a small amount of violet pigment!

As depicted in the following photo, my pallet is laid out with the warm blue, yellow and red along the left hand side, and the cool colors across the top of the pallet.   The advantage of separating the warm and colors is that it reinforces the process of migrating a color pool while painting.  As I paint, I modify the color pools on my pallet to match the colors I need in my painting by asking my self questions such as should the color on my pallet be warmer, cooler, more red, lighter, darker, etc..  This organization of the pallet makes it easier to immediately pick the appropriate warm or cool color, or the approach for tinting or shading.

The specific warm colors placed on the left hand side of the pallet include Golden OPEN Anthraquinone Blue, Naphthol Red Light, and Hansa Yellow Medium.  The cool colors are placed along the top edge of the pallet.  The specific cool colors are Hansa Yellow Light, Quinacridone Magenta, Phthalo Blue (Green Shade), and Phthalo Green (Blue Shade).  I call these seven colors the mixing colors, since these are the paint colors used to mix all of the hues that we will be using to paint.  
In addition to the mixing colors, there are four other colors on the pallet.  These are the tinting and shading colors used to adjust the value and the opacity of the various mixtures of the mixing colors.  

Tinting is the addition of white to a mixture to make the color lighter, or raising the value of the mixture.  The tinting colors on the pallet are Titanium White and Zinc White.  Titanium white is opaque and has a tendency to give certain mixtures a pastel or chalky characteristic.  On the other hand, zinc white is very transparent and does not significantly impact the hue of the color to which it is added.  Properly applied, these colors can help control both the value and opacity of the mixtures to meet the needs of the particular application.  The two whites  are placed in the upper left hand corner of the pallet, as seen above.  

Shading is adding a paint to a mixture to lower the value or make the mixture darker.  Bone black and carbon black are is my shading colors.  Bone black is reasonably transparent, has a moderate opacity and has a minimum impact of the hue of the mixtures to which it is added.  Carbon black on the other hand is an opaque color.  These shading colors are placed in the upper right hand corner of my pallet.



The following photo depicts the handout that I provide to my workshop participants that are interested in understanding and using the Augmented Golden OPEN Modern Color Set of paints.
This pallet of colors has an amazing ability to mix a wide range of colors.  In oder to understand the range of colors that can be mixed, we will view the colors on the standard color wheel.  The classic color wheel defines a color space with intense, high chroma, colors at the outer edge and dull, low chroma, colors toward the center.  The various hues, or colors, spread around as spokes of the wheel.  When placed on the classic color wheel, our high chroma modern colors are near the outer edge of the wheel, as depicted in the following photo. You can click on the image to see a larger version that is easier to read.
Note that the darker blues and green are naturally of lower chroma and are nearer the center of the chart.  As discussed later, these colors are generally tinted our mixed with higher value colors in oder to appreciate their distinct hues.

Note that each color has been plotted based on its hue (color) and chroma.  Each of the color points corresponding to the paints on our pallet are indicated on the chart above and the outer points are connected by straight lines.  This defines a five sided polygon in color space, as depicted in the photo above (you can click on the photo to see a larger version to see the details).

When two colors are mixed together the resulting mixture will fall somewhere on the straight line connecting the two original colors in color space.  Therefore, the area within the five sided polygon defines all of the colors (defined by their hue and chroma) that can be mixed by combining combinations of our seven mixing colors.  At this point I am not including use of the titanium white, zinc white, carbon black and bone black paints, since they are used to impact the value and opacity of the various hue mixtures and will be discussed later.

The area within the five sided polygon is called the "Color Gamut" of this pallet of colors, as shown in the following image.  The color Gamut defines the pool of all possible hue mixtures that can be mixed from the seven colors that define the color space.  The use of Color Gamuts is discussed in detail in a great book on color in painting, "Color and Light" by James Gurney.  I highly recommend this book for insight into how to mix, use, understand, and see color in painting.  
The following picture depicts each of the seven mixing colors at their respective positions on the color wheel. Again you can double click the image to see the details on a larger version of the image.
The highest intensity or chroma secondary colors (orange, violet and green) are mixed by combining the adjacent primary yellow red and blue paints.  For example, the most brilliant orange is obtained by mixing the yellow/orange (Y/O) with the red/orange (R/O) color, since these two colors have the largest orange pigment content of any of the pallet colors.  Similarly, the most brilliant violet is obtained mixing the blue/violet (B/V) with the red/violet (R/V) color; and the most brilliant green is obtained mixing the yellow/green (Y/G) with the blue/green (B/G) color.  These colors will fall along the outer edge of our five sided color space, as depicted in the following image.
When we mix non adjacent colors that are connected by lines that run across the color space, lower chroma or darker colors result, as depicted in the following image.
The above image depicts three color strings that cross the color space.  The red/orange and green/blue pallet paints are directly across from one another on the wheel and are hence perfect compliments.  Notice that as they are mixed, they grey each other down and create a near perfect black at the center of the wheel.  Note there are two green strings depicted; the blue/green to yellow/orange and the lower chroma (nearer the center) blue/violet to yellow/orange.  Note that both of these strings are less intense (lower chroma) than the outer edge green string depicted in the previous chart above.

The following image depicts three more color strings that cross the wheel and connect to mixed colors on the edge of the wheel.  
The lower string connects a mixed red color to the blue/green on the other side of the wheel.  Note that the red is progressively deepened as it heads to the center of the wheel and more of the blue/green color is mixed with it.  One of the values along the way matches the standard tube color of alizarin crimson.  

The next higher string connects a mixed orange to green/blue paint on the other side of the wheel.  Note that as the orange is mixed it becomes darker and browner as it approaches the center of the wheel.  The colors that it matches as it does this are the standard burnt sienna and burnt umber.

The top string connects a more yellow orange mixture with the green/blue on the other side of the wheel.  Note that as more of the green/blue is mixed with this orange, it becomes darker and browner as it heads to the center of the wheel.  However, since this string is further from the low chroma center of the wheel than the previous string, it is less dark and contains lighter browns.  Colors such as yellow ochre, raw sienna, and naples yellow can be derived from strings of this type.
Note that the paint spots near the center of the color wheel are of such a low chroma, it is hard to detect their actual hue.  This is not a problem in that we often want to use a deep color that that is related to the lighter colors around it.  However, these colors are often tinted with white to use in lighter applications, such as a blue for a sky.  To illustrate this I have included a few tints of the low chroma center colors in the lower left hand side of the chart.


This emphasizes another important aspect of color that the color wheel does not address, particularly the value, or the lightness or darkness, of the colors.  Each of the mixing, tinting, and shading colors in our pallet has a different value, as depicted in the following photo.  The values range from 1 (dark) to 10 (light).
There are three primary ways of changing the value of a color.  One is to mix it with another color, such as neutralizing it with its compliment, or any other lighter or darker color.  Any of these techinques will also change the hue to a small or large extent.  A second way is to tint the color with white, either the opaque titanium or the transparent zinc, depending on the application, such as to cover or to glaze.  The third way is to shade by adding black. either the  opaque carbon or the transparent bone, depending on the application such as to cover or to glaze.   Any of these techniques can be used, depending on the effect that is desired for each particular instance.

Summary

In summary, my augmented modern color pallet defines a very broad color space, or Gamut, as depicted by the five sided polygon in the following image.  We can view this five sided Color Gamut as our color pool, where we are free splash around and to mix any of the seven mixing colors to achieve the results we desire.
This Color Gamut contains color mixtures of an infinite variety of hues, ranging from high chroma to low chroma colors.  The reason for this is that the mixed colors will fall on the line connecting the positions of the two original colors.  For example, if you start mixing low chroma colors, there is no way that you can achieve a high chroma color, since the line connecting the two colors will be near the center of the color space.  However, since we are often starting our mixtures with high chroma colors we can achieve both high and low chroma colors, depending on the colors that we mix.  The classic example of this is mixing two colors compliments, directly across from one another on the color wheel, such as the red/orange to green/blue example we viewed above.  The line between the two complimentary colors will go straight across the color wheel and cross the center of the wheel, where the mixture will be of the lowest gray chroma and near black.

So you see the results of the various mixtures depends on the nature of the pigments involved.  As pointed out by James Gurney in his book "Color and Light", a very interesting case is to mix our Phthalo Green Blue Shade (G/B) (which has green/blue pigments) with Quinacridone Magenta (R/V) (red/violet pigments).  As depicted in the following image, the resulting string of mixtures will  include a dull BLUE!!!   Notice that I had to tint all of the colors in the string so that we can easily see the color of the mixture.
How is that for a surprise, "red and green can make blue", depending on the red and the blue pigments you mix!!!  This is how I achieved the blues and violets in my Bashi Bazouk painting depicted above, by combining Phthalo Green with Quinacridone Magenta!  Gurney points out that the old statement that the primary colors of red, blue, and yellow are the only colors that can not be created by mixing other colors is just plain wrong.  The colors that a paint can mix is just dependent of the mixtures of pigments that it contains!  So happy mixing and experimenting!  

As another example of "happy mixing" I have included the following image of one of my pallets for one of my paintings.  I use the same pallet for the life of a single painting.  Since Golden OPEN paints stay workable  for weeks or months if kept in an airtight container and occasionally sprayed with OPEN thinner.  Therefore, I can have the same color pools available to be to used or modified for the whole period of time that I work on a painting.  And, of course, I use a different pallet for each painting that I am working on, since each painting will use different color pools, depending on the color scheme of the motif being painted.
Note that for this painting I had color pools of brown, red green and blue.  Each pool I have pushed segments in different directions, such as adding a warmer or cooler color to the mix.  Notice also, that tints have bee developed for each of the color pools.
As I have recently moved into figure and portrait painting, my approach to color pool pallet management is becoming more refined and my key to successful painting.  Pictured below is a photo of quick figure study done in three classes over a three week period.  Below the painting is a photo of the pallet that i used.  Notice how color the color pools for the various warm and cool skin tones are formed by pushing the same basic orange paint pile in the center of the pallet in various directions by adding more yellow, magenta, green or blue paints.
This pictured pallet evolved over the three week period that I worked on this painting.  This is a key advantage of OPEN Acrylics when managed on the type of physical pallet that I have described previously in the Pallet Management section: THE SAME PAINTS STAYED WORKABLE ON MY PALLET FOR THE FULL TIME I WORKED ON THIS PAINTING.  This is a great advantage in that the same skin tones could be reused or modified throughout the three week painting process.  I have experienced this same advantage in other paintings where I worked on them over a several month period of evolving the same physical pools of paint.
I am finding that using this approach  to be very freeing.  I no longer have to carry around a large number of tubes of paint.  I no longer have to think in terms of matching my color needs to any particular named tube of paint.  I no longer have to think which tube of paint do I need now, "is it  yellow ochre or raw sienna that I want now?".  Rather, the color pools enable me to become more attuned to color itself.  Now I can think that that color I need is a brown with a cool red tendency.  It is then easy to move my color pool in the brown cool red direction until it has the hue that I want.  I can just concentrate on the properties of the hue desired and not the paint names!

As I do this I find that I will suddenly notice another place in the painting where the same hue, or a slightly modified version of the hue, is needed.  I am finding that color is now directing me to how paint the picture.  Very exciting.

It is interesting that years ago my son-in-law, a trained talented painter, suggested a color pool technique to me.  However, I did not have the experience to understand how to do it.  However, with experience painting, experience studying color theory, the recent availability of the slow drying Golden OPEN acrylics, and now this wonderful set of modern colors, it has suddenly come together for me.  I am now enjoying the freedom of color pool painting.  I hope my my experience can help others shorten their learning curve and enjoy this fascinating experience.

In future posts, I will expand this section to discuss strategies for defining and using color pools within the Color Gamut of this pallet, and provide additional practical suggestions for managing and understanding the mixing process.  

For now, as I mentioned previously, let me direct you to the extensive color mixing tables that the Golden paint Company has made available to describe this modern set of colors on the following links: 
http://www.goldenpaints.com/images/ColorMixingGuide.pdf
and
http://www.goldenpaints.com/images/colorMixngModernTheory.pdf
Golen also has other references in their product announcement for the new modern set of colors at the following site:
http://www.goldenpaints.com/company/news/2012/colormixing_moderntheory/
_______________________________________________________________________________
Copyright @ 2011, Joe Bergholm, All rights reserved.