Posted by Kai Hall in auto repairs on
We tend to take color for granted. Color derived from paints and other surface coatings is used to give brightness, lightness, camouflage, reflectance, pleasantness, attraction, restfulness, safety and efficiency.
The reason that we see colors and decide if it is correct or not is that the eye receives a signal and a sensation, and the brain becomes a judge as to whether it is a match or not. There is no substitute for a normal eye, but unfortunately the brain cannot remember colors so we have to keep standards and / or use instruments to produce a reference.
There are terms that are used to distinguish one color from another. This helps us to visualize, not only the type of color, but how we get from one color to another.
The word “Hue” is the generic name used to describe what everyone thinks of as color, in the form of red, green, yellow, orange, or the quality which causes it to vary from one part of the spectrum to another.
The word “saturation” is used to grade the purity of a color. The more saturated the color the closer it is to a true version of that color. Primary colors, which are yellow, blue and red are “true colors”, so they are also fully saturated. The term “chroma” is used to indicate the degree of strength or saturation of a color.
There are two other extremes which determine a color. These are “Paler” to “Deeper” or Stronger”, and “Lighter” to “Darker”.
Deciding whether a color is paler or deeper determines the percentage or concentration of the color.
Going from lighter to darker in paints tells us how much black or white is in the color, where the middle of the scale contains neither and is the pure color. This is also known as the “color value” or “tone”, and the words “tint” or “shade” are used to denote the addition of white or black.
Additive color matching is used when lights are being passed through the color filters of red, green and blue.
The color produced by a mixture of pigments (solid materials) as in paint, is the result of selective color absorption. Color matching of paints is subtractive. The subtracted primaries are red, blue and yellow. When they overlap they produce secondary colors i.e. purple, green and orange. When these colors are all mixed together they will produce black.
“Metamerism” is the term used when two shades look the same in one light, but differ when the illuminant is changed. To clarify this, as colors appear to change under different lights, if they are metameric they will not change by the same degree. An example of this is when sodium street lights make blues and greens become greys and blacks, and mercury lights which make oranges and reds become greys and browns. Colors that match in all lights are known to have a “spectral match”.
To aid the distinguishing of one color to another, a system of color code or notation was devised by an American art teacher from Boston, Albert Munsell (1858-1915). He started work in the early 1900’s producing his first color chart, but his complete color atlas was not published until after his death in 1918.
He developed his system to distinguish uniform steps of difference in the appearance; in particular the difference in the value and chroma.
The system takes the form of a three dimensional solid. A circular band around the central axis represents the hues in their proper sequence, i.e. red, yellow, green, yellow, blue-green, blue, blue-purple, purple and red-purple. Each of these hues is sub-divided into 10 parts providing 100 hues in all, but for practical purposes 40 hues are used, principle colors appearing at 5.0 and others at 2.5, 7.5 and 10 respectively.
For value, Munsell shows on his central axis a scale of neutral greys in equal steps (0 – 10) of increasing lightness from theoretical black at the base (0) to theoretical white at the top (10). In theory, under average daylight, all colors have the same reflectance factor.
For chroma, Munsell shows along the horizontal branches the scale of chroma in equal steps of equal increase in strength. (Most charts move 2 steps at a time).
An example of a typical Munsell reference such as “2.5 GY 6/4, 2.5 GY” represents a green-yellow with a hue of 2.5, a value of 6 and a chroma of 4.
The Munsell system, having a numerical basis is capable of sub-division and extension. Therefore, if stronger colors become available a place exists for them.
Color has transformed our world and can invoke a variety of emotions, but we all expect consistency in our world, especially in corporate identities and where repairs are required. Color matching in the laboratory is a highly qualified science, with the need for a certain eye to brain connection and a sound knowledge of pigments and their purity. However, we all have an appreciation of color, and if we understand the intricacies of color we can use colors better to enhance our world even more.
Nigel Le Monnier has 11 years experience in the Paint Industry specialising in vehicle body refinishing and Industrial paint application. For the last 23 years he has been the Director of a Health Food business, with the aim of bringing awareness of the joys of natural living and healthy eating to everyone.