10 SOURCES OF COLOUR, QUALITIES – PRANG, MUNSELL AND OSTWALD COLOUR SYSTEM

S. Prema

    Colour is an inherent visual property of all forms. We are surrounded by colour in our environmental settings. The colours we attribute to objects, however, find their source in the light that illuminates and reveals form and space. Without light, colour does not exist.

When white light falls on an opaque object, selective absorption occurs. The Surface of the object absorbs certain wavelengths of light and reflects others. Our eyes apprehend the colour of the reflected light as the colour of the object. Which wavelengths or bands of light are absorbed and which are reflected as object colour, is determined by the pigmentation of a surface. A red surface appears red because it absorbs most of the blue and green light falling on it and reflects the red part of the spectrum, similarly, a black surface absorbs the entire spectrum, a white surface reflects all of it. This distribution of colour in light rays is reflected as a rainbow on a rainy day when the light ray passes through a water droplet, which acts as a prism.

A surface has the natural pigmentation of its material. This colouration can be altered with the application of paints, stains or dyes which contain colour pigments. While coloured light is additive in nature, colour pigments are subtractive. Each pigment absorbs certain proportions of white light. When pigments are mixed, their absorptions combine to subtract various colours of the spectrum. The colours that remain determine the hue, value and intensity of the mixed pigment.

QUALITIES OF COLOUR

How colors differ from one another

There are three properties or qualities which may be called the dimension of color, and which are just as distinct from one another as the length, breadth, and thickness of an object. These color dimensions are:

• Their warmth or coolness (the hue or name of the color)
•  Their lightness or darkness (the value of the color)
• Their brightness or dullness (the intensity or chroma of the color).

All three of these dimensions-hue, value and intensity-are present in every color, just as every object has length and breadth and thickness.

HUE (SYMBOL H)

Light-the source of color

Hue is the term used to indicate the name of the color, such as red, blue, or green. The difference between blue and green is a difference.

Hue is used to describe a kind of a colour, and is practically synonymous with the term ‘colour’ itself such as red, yellow, blue, green, etc. The difference between red and blue is the difference in their hue. If a person wishes to change the hue of acolour, he will mix it with some of a neighboring or adjacent hue, for example, some red added to blue will change its hue to purple. A change of hue may be accomplished by dyeing, or by putting a semi-transparent fabric over the colour. Some very interesting effects may be obtained by his process.

HUE

In the pigment colour chart, the hues fall into two large groups, one on either side of the vertical line (refer Fig. 5.4), Hues on the right side near the blues are the cool hues, and those one the left side around red and orange, are the warm. Red and orange are the warmest of all the colours, and they seem to advance the most and thus, be the most conspicuous, Blue and blue-purple are the coldest hues and they seem to recede and become inconspicuous. Green is between heat and cold, but it gets warmer as it grows yellowish, and becomes cooler as it grows bluish.

Hues and Seasons

Certain hues seem to be particularly appropriate to the difference seasons of the year. Window decoration and advertisements may be made to suggest the seasons, if colours are chosen according to the following plan:

• Spring: Starting with blue, through blue-green to green
• Summer : Green, yellow-green and yellow, approaching a yellowish-orange towards the end of summer
• Autumn :Orange, red and red-purple 
• Winter: Purple, blue-purple and blue.

EFFECT OF HUES

Warm hues are more cheerful and stimulating than cool hues which are calm and restful. This quality of a colour, i.e., warm and cool, can successfully be used to counter such effects in a room. A room which is facing south west or west, receives high intense sunlight during the day, and this makes the room remain warm, especially during summers. A cool colour scheme with blues, blue greens etc., can help to counter this effect. Similarly a north or north east facing rooms becomes very cold during winters, since it does not receive any sunlight at all day time. A warm colour scheme of orange, red and yellow, is appropriate, since it would provide an atmosphere of warmth in those rooms.

When used on an enclosing place of space, cool hues appear to recede and increase apparent distance. They can, therefore, be used to enhance the spaciousness of a room, and increase its apparent width, length or ceiling of all rooms. Any warm colour used for the ceiling might give a feeling of advancing towards the persons who are present in the room! Warm hues thus appear to advance and suggest nearness. These traits can be used to diminish the scale of a space or, in an illusory way shorten a room’s dimensions.

How to change hues

If a person wishes to the change the hue of color, he will mix with if some of a neighboring or adjacent hue. For example, some red added to blue paint will change its hue to purple. A change of hue may be accomplished by dyeing, or by putting a semitransparent fabric over another color. Blue can be turned toward purple by putting red or red-purple under or over it, and toward green by the use of yellow or green.

Warm and cool hue

The hue will fall into two large groups, one on either side of the vertical line. The colors at the right of the line near the hues are the cool hues, and those on the left side of the vertical line, around red and orange, are the warm, Red and orange are the warmes of all the colors, and they seem to advance the most and be the most conspicuous, Blue and blue-purple are the coldest hues, and they seem to recede and become inconspicuous. Green is between heat and cold, but it gets warmer as it grows yellowish, and cooler as it grows bluish. This quality of warmth and coolness is the most important thing to remember about hues. There is a harmony among the warm colors because they are related to one another, and the same harmony or family quality exists among the cool colors; but the warm and cool colors are strangers to each other. As white complements black and heat complements cold, so are warm and cool colors complements; they contrast rather than harmonize.

Advancing and receding hues

The warm advancing hues will make objects appear larger and nearer to the observer, while the cool hues, which seem to recede will appear to reduce size.

Effect of difference hues

Hues have a decided effect upon one’s feelings, and it is important to know how people react towards color schemes. People tire more quickly of the six standard colors- clear green, yellow, orange, red, purple, and blue-than they do of the intermediates-yellow-green, yellow- orange, red-orange, red-purple, blue-purple, and blue-green. Warm colors are more cheerful and stimulating than cool colors, which are calm and restful.

Value

The value of a colour refer to its darkness or l’lightness. There are may degrees of light and dark, ranging all the way from white or black. By adding white a colour is lightened, and by adding black, a colour is darkened. White has the highest value and black the lowest, if the colour chart is compared with the value scale, it will be seen that the hues change gradually in value with the lightest at the top and the darkest at the bottom as depicted in Table 1 below

Table 5.1: Value Scale and Step in a colour wheel

So, by adding white to a colour, we obtain a lighter colour, i.e a ‘tint’, By adding black to a colour, we obtain a darker colour, a ‘Shade’. When grey is added to any colour, its tones are obtained. Thus, technically speaking, pink is a tint of red and a\maroon is a shade of red. The term ‘tone’ refers to a range of tints and shades of a colour. Tones are obtained by greying the colour. For instance, in the above example, greyish red is the tone of red. See the value chart given in Table 5.1. In interior design, mostly tints are used. Pure colours and shades are used sparingly (Figure 5.1- see colour plat 9).

IMPLICATIONS OF VALUE

1.  Light values seem to increase the size of objects. Small room may be made to appear larger, if furnished in lighter colours. Also, light values create the impression of distance. A low ceiling can be made to have a raised effect by painting it white.

2.  White and other very light values reflect colour and seem to intensify colour of objects seen against them, and vice versa.

3.  Black and dark values seem to decrease the size of an object. Therefore, a small room should not be furnished in dark colours. Instead, dark values seem, to be amking a large room to appear small. A large room where light colours are used in their furnishing, may seem empty. Instead, dark coloured furnishing can help this room to appear adequately furnished. Besides, darker values of a colour are particularly appropriate for floors and rugs because they give to the room an impressiono stability. In store display, dark values should be used below, rather than above light values, for if they are seen above the light colours the display will appear unstable. As it appears in Table 5.1, dark value shades are to be used at lower levels and lighter values tints at higher levels. It is no wonder that all room ceiling are done with white paints which is the lightest colour!.

4.   In home furnishing, close values are agreeable if maycolours are to be used, Close values produce quiet effects, strong contrasts have the opposite result. Although, many colours add interest to a room, but if used too much, the effect of unity may be lost. Therefore not more than three or four values are to be used at one time in a room.

5.  To bring attention to an object which is a\esthetically good, it should be placed against a back ground of very difference value ot emphasize the object. But, when an object is not beautiful, and least attention is desired, it should be placed against a background very near its own value, to have a subdued effect.

Value, the second dimension, describes the lightness or darkness of a color. Three are any degrees of light and dark, ranging all the way from white to black, but for the sake of convenience in use, nine typical steps are selected, Dr. Denman W. Ross gave these nine steps names and symbols to aid in visualizing them. White is the highest value, and no hue can be as light as white. Black is the lowest value, and no hue can be dark, Halfway between black and white comes middle value, (See figure 160A.) The value scale begins with White at the top (symbolized by W0, The next step is High Light (HL); then come Light (L), Low Light (LL), Middle (M),High Dark (HD), Dark (HD), Dark (D), Low Dark (LD), and Black (B),

If the color chart is compared with the value scale, it will be seen that the hues change gradually in value with the lightest at the top and the darkest at the bottom. The table below gives the value equivalent of the normal colors.

• HL = Yellow
• L  = Yellow Orange and Yellow-Green
• LL = Orange and Green
• M  = Red-Orange and Blue-Gree
• HD = Red and Blue
• D = Red-Violet and Blue-Violet
• LD = Violet

HOW TO CHANGE VALUES

Values can be changed by adding white or water to lighten and by adding more pigment or black to darken them, Every hue is capable of being lowered to a value just above black, and of being raised to a value just under white. Values that come above Middle are commonly called high values and those below Middle are the low values.

TINT AND SHADE

A value that is lighter than the normal color is called a tint, and one that is darker, shade

INTENSITY (SYMBOL 1) OR CHROMA (SYMBOL C)

Intensity or chroma is the dimension that tells the brightness or dullness of color-its strength or its weakness.

The colors at full intensity are very striking and form brilliant and interesting effects when they are used with discretion. The colors in the lower intensities are more subtle, and for general purposes they are enjoyed in the large areas with the colors of full intensity used for accents.

As colors go down in their brightness and toward neutral gray, or no-color, they are said to be of low intensity or chroma.

Intensity or chroma is the saturation or purity of a colour, i.e. it represents its brightness or dullness. In other words it shows the presence or absence of grey or dullness. In a nutshell it can be said it is the property describing the distance of the colour from grey or neutrality line as in the case of the lemon which is brighter than the banana though both of them are of the same colour. A colour in its purest form has the greatest brilliance or intensity. Therefore, intensity is that quality if colour that makes it possible for a certain hue, such as red, to whisper or to shout, or to speak in a gentlemanly tone.

The colours at full intensity are very striking and form brilliant and interesting effects. The colours in lower intensities are more subtle and are enjoyed in large areas, whereas colours in higher intensities are to be used in small areas. Similarly, larger the area to be covered, the less intense the colour should be and the smaller the area, the brighter the colour may be. Colours in background are usually painted somewhat dull, grayed or neutralized because it is easier to live with them in large amounts. Saturated colours or colour with pure intensity are often reserved for small areas like hall-ways or cloakrooms where people do not spend a great amount of time. Intense or bright colours are also used for accessories and for flowers in an arrangement since they draw more attention than other colours.

Changes in the intensity of a colour may be brought about through mixing the complementary colour which lies opposite on the colour chart. When complementary colours are mixed, they neutralize each other and when mixed in certain proportions destroy each other and produce gray or neutrality.

A colour may be emphasized in the following way

1. By placing it next to its complement e.g., -red against green orange against blue

2.By combining the colour with another neutral colour like black or white which will emphasize colour more than does grey, or black.

3. By repeating near, it a large amount of the same hue in a lower intensity. For example, a little bright green surrounded with dull green would become more emphatic.

4. By repeating in some other part of a composition a small note of the same hue in a brighter intensity.

THE PRANG COLOUR SYSTEM

The system developed by David Brewster is probably the best known colour system and is often referred to as the Prang Systems.Colors may be divided into five classes: Primary, binary, intermediate, tertiary and quaternary. All colors may be obtained by mixing in various proportions three dundamental hues: red (R), Yellow (Y), and blue (B), These are called the three primary colors, because they are the elements in the use of pigment. They are the only hues in pigment that cannot be obtained by mixing other hues.

When two primary colors are mixed in equal amounts a different hue will result. This new hue is called a binary or secondary color. There are three of these binary colors-purple (P) called violet(V) in the Prang System, made by mixing red and blue gree (G), made by mixing yellow, and ble and orange (O), from red and yellow.

The Primary and binary colors together are commonly called the six standard colors.When a primary and a neighboring binary are mixed an intermediate hue results. In appearance, the intermediate is halfway between the two colors. There are six of these intermediate hues: yellow-green (YG), blue-green (BG), blue-purple (BP) or blue -violet (BV), red-purple (RP), or red-violet (RV), red-orange (RO), and yellow-orange (YO), so far the twelve hues that constitute the typical color chart have been placed. However, there is room between each one of the intermediates and its neighbor for an indefinite number of gradations. For example, one can easily imagine a color halfway between the blue and the blue-green on the chart. These hues may be indicated by repeating the name of the more conspicuous one. Thus, the hue called peacock blue, which is between blue and blue-green, would be called blue-blue-gree (BBG). Next on the spectrum would appear the blue-green (BG), then green-blue-green (GBG), and green (G), Obviously it is possible to make more and more detailed.Charts recording steps between the standard and intermediate hues.

When two binary colors are mixed a tertiary results. The tertiary colors are yellow, blue and red, much neutralized. Tertiary yellow resembles as smoky-yellow the blue is known as slate blue, and tertiary red is the color of old red brick. The following analysis illustrates how tertiaries are obtained: Tertiary yellow is a mixture of green and orange. Green is B + Y and orange is Y + R, and when they are mixed the color will be predominantly yellow with some purple from the red and blue. This purple will neutralize part of the yellow leaving the color a grayed yellow. Tertiary blue is a mixture of purple and green, for R+B+B+Y gives principally blue dulled by orange from the R+Y. Tertiary red is orange mixed with purple, for Y+R+R+B gives red dulled by green from the Y+B..

A mixture of two tertiary colors gives a quaternary. The quaternary colors are green, purple, and orange, much neutralized. They are sometimes spoken of as olive, prune and buff. Quaternary green is a mixture of the tertiaries yellow and blue. Tertiary yellow (B+Y+Y+R), added to tertiary blue (R+B+B+Y), gives this sum of colors-three parts of yellow, three parts of blue and two parts of red. The result of the mixture is green, from the predominance of yellow and blue, and it is much dulled with the red. The quaternary purple is a mixture of the tertiaries blue and red. R+B+B+Y and Y+R+R+B makes three parts of red and three parts of blue, giving purple, with two parts of yellow to dull it. Quaternary orange is tertiary red (Y+R+R+B). This makes three parts of yellow and three parts of red, which give orange and the two parts of blue neutralize the orange.

The simplest way to understand colour relationships in this colour system is to study a colour wheel based on three primary colours- yellow, blue and red. These three hues are called primary in the Prang System because they cannot be obtained by mixing other pigments and also because the other colours are obtained by mixing these three colours in varying proportions. Theoretically, starting with five cans or tubes of paint-the three primaries plus black and white-one could build an entire range of colours. However, this is not practical, because to achieve the exact gradations in colour, it requires precise mixing of difference pigments.

The secondary colours are orange, green and purple. They are obtained by mixing two primary colours in equal quantities. For example, mixing of yellow and red together in equal quantities make orange colour. (Refer Table 5.3)

Primary and Secondary Colours

Primary and Secondary colours together form ‘normal colours’. When a primary and a neighboring secondary colour are mixed, an ‘intermediate or a tertiary hue’ results. In appearance intermediate is halfway between two colours. There are six intermediate hues namely- yellow-orange, green-yellow, blue-green, blue-purple, red-purple and orange-red as illustrated in table 5.4

Some of the popular colours like pink, brown, lavender, beige etc. are not in the list of above colours but each of these can be described accurately by using the name of the hue with which it matches in the spectrum. A mixture of two of two tertiary colours is quarternary colour. For example tertiary yellow combined with blue gives quartenary green.

THE MUNSELL COLOUR SYSTEM

In the Munsell plane, the dimensions of colour are shown upon a sphere. The hues appear around the circumference of the sphere. Values in neutral grey are shown upon a vertical pole-the axis of the sphere. The ‘North Pole’ is white and the ‘South Pole’ black. As the hues become lighter in value, they are placed higher on the sphere, and as they grow darker they appear lower, toward the ‘South Pole’. Chroma or intensity is represented by paths or arms running from no-colour, or Neutral Grey, out to the circumference and beyond it.

Munsell found that if hues were in proper balance around the sphere and this sphere were rotated up on its neutral axis at a high rate of speed, the hues would blend together to form a neutral gray. He decided to use five principal hues in order to make use of the decimal system. The chosen hues were named Red (R), Yellow (Y), Green (G), Blue (B), and Purple (P). The hues intermediate between these were named Yellow-Red (YR), Green-Yellow (GY), Blue-Green (BG), Purple-Blue (PB),& Red-Purple (RP).

Instead of the twelve-hue circle we now see ten major hues divided into five principal hues and five intermediate hues. Munsell did not include the colours violet and orange because they represented the names of flower and fruit respectively.

Numerals are used designate the hues lying between the principal and intermediate hues. Principal blue would be 5B; intermediate hue 6 blue-green would be 5 BG. The hues lying between 5BG and 5B are designated as follows: 6 BG, 7B6, 8B6, 9B6, 10B6, (the midpoint between 5B6 and 5B), 1B, 2B, 3B, 4B, 5B, the 6B6, has little more blue in it than 5BG; 9B6 is four steps from 5B6 and six steps from 5B, 10, B6, is just half way between B6, and B. The other steps-1B, 2B, 3B, 4B all show more blue and less blue-green until they read 5B.

Values, in the Munsell plan, have numbers, Ten steps are charted between black and white. Absolute Black (which the eye cannot see), is O, and is written No/. Absolute white is N10/. Halfway between black and white is Middle value, or N5/.

The full strength of the weakest hue-blue-green determines the circumference of the circle, and all other hues extend beyond the circumference in the degree of their relative strength. The scale of red chroma is written R/1, R/2, R/3, etc. Chroma is an almost grey but is recognizable as a warm grey and each succeeding step is nearer to the strongest visible red.

In the Munsell notation, colour symbols are expressed as follows, hue, value/chroma. Thus the five principle hues as they appear in the fullest intensity now obtainable with permanent pigments would read as follows. R4/14, R8/12, GS/8, B4/8, P3/12. The five intermediate hues would read: YR 5/12, GY7/10, BG 5/6, PB3/12, and RP 4/12.

A study of colour theories and qualities is essential for planning colour schemes for a room. It requires a great deal of knowledge and thought for achieving success in their use, because we find infinite variety of colours both in natural and artificial objects.

References:

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