Primary and secondary colours
The concept of «primary colors» dates back to Isaac Newton’s book Opticks (1704). New scientific approaches and discoveries have kept the identification of primary colors under constant revision and evolution.
Despite the existence of several color models that identify different primary colors, models with three primary colors predominate. This preference for three primary colors is explained by human trichromatic vision, which explains that we have three different types of receptors, each responding to different wavelengths.
Secondary colors are a basic subject of color theory that every visual arts professional should master. In this way, you will be able to apply this knowledge when mixing and matching colors in your projects.
Secondary color is the color obtained from the mixture of two primary colors, which is in turn a complementary color of a third primary color, the one that does not intervene in its elaboration.
The main difference between primary and secondary colors is that secondary colors arise from the mixture of primary colors, while primary colors cannot be obtained from any mixture.
Origin of the chromatic circleIsaac Newton was the first to study primary colors and their derivatives in his book Opticks (1704), stating that there are seven basic colors in light. He also made important contributions to optics, such as the creation of the first chromatic circle.The chromatic circle as we know it today arises from the primary colors. In this circle the primary colors can be observed in equidistant positions, where the mixture of two primary colors gives rise to secondary colors, and from the mixture of a primary color with its secondary a tertiary color arises.Newton discovered that these colors that we perceive can be identified thanks to light, because it reflects the pigment of the substances that compose them.The human eye through the receptor cells can identify colors and interpret them through a biological process of response that is possible thanks to light and its interferences. Depending on the longitudinal distances, the eye will interpret different colors.
On the other hand, most mammals possess only two types of color receptor cones and, therefore, are dichromats; for them, there are only two primary colors, in the same way that happens with people who have the genetic defect that causes color blindness in its different degrees, in which the L and M cones develop incorrectly and prevent the perception of shades of red and green.
The idea of color mixing existed since Ancient Greece; however, the theory of the existence of primary colors and their derivatives was developed by Isaac Newton and published in his book Opticks (1704). Newton proposed that -like musical notes- there were seven basic colors in light, giving total relevance to the tones that stood out most in the spectrum of a prism, which idealized the model without taking into account that, in the phenomenon of light scattering, there is a tonal gradation corresponding to a uniform distribution of frequency ranges.
Warm and cool colors
Red is located at the top of the circle, and then, clockwise, come orange, yellow, green, green, blue and violet. A tip: if you draw or paint your own chromatic circle, you will memorize in a lasting way the relationships between the colors. If you place it near your workplace, you will be able to check the mixtures in the blink of an eye.
How to make a chromatic circle? Draw a circle divided into 6 equal parts and apply the different colors according to the scheme. Paint the three primary colors first. For the secondary colors, mix in equal proportions the pairs of primary colors and then apply them in the circle.
Within the chromatic circle, they are placed at 120º to each other: they are red, yellow and blue. They are called primary colors because they cannot be obtained by mixing other colors. On the contrary, they serve as the basis for different mixtures, called secondary colors.
The mixture of the complementary pairs gives a whole range of grays and browns. You can vary the proportions of the mixture to infinity and thus have a very wide palette of grays more or less cold, and browns more or less soft.