TERTIARY COLORS and understanding the THREE PRIMARY COLOR MIXING PROCESS

A tertiary is a mix of the three primary colors.  It can also be a mix of a secondary and its opposite complementary color on a color wheel.

Promulgated by one author and copied by others, a mistaken and useless definition is that a tertiary is “an equal mix of one primary and an adjacent secondary”- which of course still makes a secondary color.

To understand the absurdity of this definition, let’s mix some colors.

[Secondary color: single pigment and mixed]

First, an obvious confusion is in examples often given of so called “tertiary” colors.   (top row) Ultramarine blue (A), Cerulean blue (B) and Cadmium yellow deep (C). These colors are readily mixed from two primaries as shown in the bottom row (A,B,C) and thus should be called secondary colors.  

Second, because pigments have unequal tinting strength it is misleading to suggest that mixing equal amounts will result in the anticipated color. The middle row shows the approximate amount of each primary in the admixtures that match the single pigment paints in the top row. The primary paints used to mix the colors are Winsor Lemon (PY175), Winsor (phthalo) blue red shade and Permanent rose (PV19).

[Engraving plates showing the three color separation]

The term tertiary originated through the color printing process when printer Jakob Le Blon 1667-1756 separated the red, yellow and blue components of a composition by making an engraving for each. He then applied the three plates sequentially to a sheet of paper in a primary, secondary and tertiary application over the line engraving. The primary and secondary applications produced “prismatic”, saturated colors as in the spectrum. Duller or “compound” colors resulted in the tertiary application when the three primary colors overlapped.

Primary and secondary color pairs red/green, yellow/purple and blue/orange are placed on the outside ring of a color wheel. They are equidistant and placed opposite one another. The first color wheel with this arrangement was devised by Moses Harris in 1766.  The opposite pairs are so placed because they complete the subtractive color mixing process of making black when combined in the correct proportions.

The term complement was coined by Goethe in his 1810 “Theory of Colors” to describe the color produced by the eye as an afterimage when we view a color.

Artists combined the information and called the color pairs complements and used them to dull down color. For instance, Permanent rose (primary red) will be dulled if a touch of green is added to it.

The color pairs for visual complements that are used for color enhancement and determining color schemes are different from the mixing complements since they complete the visual synthesis rather than the subtractive mixing process. For instance, the visual complement of lemon is blue rather than the orange/blue pairing of the mixing complements. Thus lemon appears brighter if juxtaposed with ultramarine blue and vice versa. Most artist books on color unlike those on interior decorating, wrongly use mixing complements to devise visual color schemes. The color pairs are not the same. (see my article on visual complements at www.hilarypage.com .)

DEFINITIONS

Primary paint colors s are those that match the printers’ primaries - a yellow, magenta and cyan. The paint equivalents are Winsor Lemon (PY175 or PY138), Permanent Rose PV19 (red shade) and Winsor (phthalo blue) red shade PB15.1 . These paints will yield the greatest number of saturated (clear) colors . However, artists rarely use just the three primaries to make a painting. The point of working with the three primaries is that it teaches us about color mixing and how paint color is comprised.

Secondary color describes the “saturated” colors i.e. that are clear and unsullied. The colors match the clarity of spectral color as far as possible. The term often refers to orange, green and purple- colors that are placed opposite and complement the three primaries.

[Tertiary color: single pigment and mixed]

Tertiary, meaning dull to neutral color, reminds us that dull color such as yellow ochre(D) and burnt sienna(E) (top row) are combinations of three primaries (lower two rows).

Hilary Page  hpage2@comcast.net