Why are black and white not primary colors?
If color is solely the way physics describes it, the visible spectrum of light waves, then black and white are outcasts and don't count as true, physical colors. Colors like white and pink are not present in the spectrum because they are the result of our eyes' mixing wavelengths of light.
But in a technical sense, black and white are not colours, they're shades. They augment colours.
Black is said to be “the sum of all colors” when a blackish stain is obtained from the mixture of various pigments. And black is said to be the “absence of color” when all light radiation is removed.
Robert Boyle, the Irish chemist, introduced the term primary color in English in 1664 and claimed that there were five primary colors (white, black, red, yellow, and blue).
Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed of black and white. It is the color of a cloud-covered sky, of ash and of lead.
It has been determined by people who determine such things that there are somewhere around 18 decillion varieties of colors available for your viewing enjoyment. That's an 18 followed by 33 zeros.
Three Primary Colors (Ps): Red, Yellow, Blue. Three Secondary Colors (S'): Orange, Green, Violet. Six Tertiary Colors (Ts): Red-Orange, Yellow-Orange, Yellow-Green, Blue-Green, Blue-Violet, Red-Violet, which are formed by mixing a primary with a secondary.
White light is a combination of all colors in the color spectrum. It has all the colors of the rainbow. Combining primary colors of light like red, blue, and green creates secondary colors: yellow, cyan, and magenta. All other colors can be broken down into different combinations of the three primary colors.
Technically, pure white is the absence of color. In other words, you can't mix colors to create white. Therefore, white is the absence of color in the strictest sense of the definition.
Why is pink not a colour?
If colours were simply a naming scheme for wavelengths then pink is not one, because it is made up of more than one wavelength (it's actually a mix of red and purple light). If you took a laser and tuned it across the visible wavelengths, from infrared through to ultraviolet, you would not pass pink on the way.
Black is not a color; a black object absorbs all the colors of the visible spectrum and reflects none of them to the eyes. The grey area about black: A black object may look black, but, technically, it may still be reflecting some light.
Exploring the essential properties of painting, The Other Primary Colors: Black, White and Gray provides a fresh perspective on the way we view art.
Primary colors are the basis for all other color combinations. That's why they are called “primary” - they are the “first” colors for mixing. Black, in that context, does not mix to make any another color. Black is essentially not considered a color but absorbs all light and doesn't reflect out any color.
- Three Primary Colors (Ps): Red, Yellow, Blue.
- Three Secondary Colors (S'): Orange, Green, Violet.
- Six Tertiary Colors (Ts): Red-Orange, Yellow-Orange, Yellow-Green, Blue-Green, Blue-Violet, Red-Violet, which are formed by mixing a primary with a secondary.