What are the correct primaries in the color wheel, in regards to mixing guache paint? Is it magenta, ultramarine and primary yellow?
The correct primaries for pigment-based color are cyan, magenta and yellow. Ultramarine is too "warm" a blue to be used as a primary color. Instead you should purchase a phthalocyanine blue. Most paint companies now offer "primary yellow", "primary magenta" and "primary cyan".
What kind of color wheel would be best for working in motion graphics?
We are currently working on a wheel/video combination for use with motion graphics. The problem here is that we are dealing with light, and this is difficult to represent on a pigment-based wheel.
The same principles of color apply here (i.e. color contrast, complementary colors, triadic relationships, etc.) as in pigment-based color, except that when you mix colors, you will of course get a different result with light than with pigment.
Also, when you are dealing with color for video, luminosity and saturation become important factors, as high luminosity or saturation tends to bleed on the TVscreen.
For finding color relationships, our new CMY wheel (which will be available in a month or two) sounds like a good place to start. This wheel shows all the color cords, or relationship "themes" to use for dynamic color effects.
Does it matter whether the warm colors are on the left side of the color wheel or the right side?
This is an interesting question, and one that took a bit of research to come up with our answer.
We believe that, although there seems to be no specific rule pertaining to this, warm colors should be on the right, for the following reasons:
In 1931, the CIE (Commission International de l'Eclairage) developed an international standard of color by measuring the wavelengths of visible color.
The CIE "triangle" is a horseshoe shaped schematic of color wavelengths ranging from around 400 millimicrons (blue) to around 750 millimicrons (red). This is laid out on an x:y coordinate system. Pure colors are arranged on the outside of the triangle, with white light in the middle. Using this coordinate system, virtually all visible colors can be mixed.
Green is placed at the top of the CIE triangle (being the middle wavelength, around 520 millimicrons), moving clockwise to red on the right, variations of magenta to violet along the bottom line, blue on the bottom left, and cyan on the mid-left. The placement of the colors is based on color temperature, and wavelengths.
(Interestingly, this is the color space upon which all computer based color systems operate. RGB color is calculated from CIE Lab color, and when RGB color is converted to CMYK for printing, it first must be translated through the CIE color space.)
Around 1975, Gerritson improved upon the basic (subtractive) color wheel by adding missing hues, and placing colors according to their inherent value levels (light to dark), with yellow being on top because it is lightest. In doing so, he essentially rotated the pure hues of the CIE color triangle counter-clockwise to place yellow on top, with green being passed to the left, blue at the bottom, and so forth.
Another interesting item is that red is the topmost color of the color spectrum seen in the rainbow, and through a prism. Western civilization traditionally reads from left to right, and it seems to make sense that from yellow, the next most visible color in the spectrum is red, flowing in a left-to-right fashion.
Of course, the color wheel is only a 2-dimensional representation of the color solid, and in 3-dimensional space, the question of right and left flies out the window, as the solid can be rotated.