Chroma is the strength of a color. It is the quality by which we distinguish a strong color from a weak one. The standard hue is approximately full chromatic intensity. Likewise each tint and shade is considered to be of its full chromatic intensity, making the left-hand boundary of the rectangle the area of full chroma.
From this boundary, each tint, standard, and shade fades out or loses chroma until the right boundary of the rectangle is reached. In this boundary each tint, standard, and shade has faded out of its gray equivalent, but without changing its original value; in other words it has traveled along its horizontal value line to a complete grayness. The right-hand boundary of the rectangle may then be represented by a gray value scale of nine steps, including white and black.
It becomes necessary to record at regular intervals, this loss of chroma. For this purpose, we have cut the hue rectangle by three vertical lines. The first vertical line from the left boundary of the rectangle marks the position where the standard with its tints and shades have been grayed to the point where only three-fourths of the original of hue remains. Similarly, the center and right vertical lines mark the points where one-half and one-fourth, respectively, of the color have been retained. These losses of chroma are recorded by similar fractions. With possible modifications of value and chroma each hue now has twenty-seven possible changes.
The full hue title or symbol may now be written as follows: (1) hue name, (2) amount of chroma, (3) value. Examples: GB¾D-V½HL. We are now in a position to write whatever color we may have in mind and another person will understand it, provided the other person adopts our standard. Through the teachings of Dr. D.W. Ross, Mr. A.H. Munsell, and others, the symbols and standards are now quite generally understood and have, in a slightly modified form been accepted in several standard color industries.
To familiarize oneself with the mixing of the various hues, it is excellent practice to form a vertical gray scale of the three-quarter-inch squares. There should be nine steps from white to black; an enlarged duplication of the right boundary of the hue rectangle. The warm standard hues at their full standard intensities; RV-R-OR-O-OY-Y, may be formed and placed opposite their gray equivalents on the left side of the gray scale, while the remaining or cold colors may be similarly placed with relation to the gray scale but upon the right of it.
A vertical scale of tints and shades of one of the hues, duplicating the left side of the rectangle gives the character of the tints and shades. One shade and one tint should then be carried along a horizontal value line through three steps of loss of chroma to complete grayness, but without change of the original value. Yellow, by the addition of black becomes a false greenish shade which may be corrected by the addition of a small amount of vermilion.
A large percentage of natural wood hues are to be found between the hue rectangles, Red-Orange, Yellow and Green, or in the warm portion of the spectrum. As a wood stain must blend harmoniously with the natural wood color, it is reasonable to expect the best results from stains with a predominance of warm hues or warm grays in their composition.
It is possible to duplicate nearly all the twelve standard hues of Figure 455 with mixtures of the three so-called primary hues of red, yellow, and blue. It makes a fairly approximate scale which is, however, not sufficiently accurate for standardizing purposes. The scale is formed by mixing red and yellow in varying proportions for the intermediate hues of orange, yellow, and blue for the greens, and blue and red for the violets. This practice of mixing three primary colors together serves as an important step, governing wood stain mixing for beginners.
Developing this idea further, we may select aniline brilliant scarlet as approximating red; metanil yellow, approximating yellow; and acid green as a substitute for blue. These stains are shown in the top portion of Figure 456. By comparison with Figure 455, scarlet is found to be orange red; metanil yellow, orange, and acid green to be true standard green. These basic stains have been located in their proper positions with regard to their hue, value, and chroma. Their positions are located by the large circles in the hue diagrams of Figure 456.
These stains are modified and reduced in chroma and value by mixing them with nigrosene black, an aniline dye of blue black appearance, which fills all the needs of an ivory black in water or oil color pigment. With these four stains, almost any commercial stain may be duplicated. Aniline dye for water stains readily dissolves in water while a special aniline for oil staining is first cut with naphtha.
Dark mahogany stain in Figure 456 is orange red, ¾HD, and is indicated by the circle A in the same figure. To duplicate this stain we have as the nearest base stain, brilliant scarlet, which corresponds to orange red. This is placed at its full intensity in the circle OR on the middle horizontal value line. To duplicate dark mahogany stain it will be necessary to reduce in value a strong solution of brilliant scarlet, slightly more than one horizontal value step, by the addition of nigrosene. We shall then add a small amount of some thinning medium, oil or water, to reduce slightly the stain in chroma.
Flemish oak stain is orange ¾D. This calls for a mixture of metanil yellow and brilliant scarlet aniline to form the orange hue. We must then add nigrosene to reduce the value to D, and add a small amount of thinner to produce the necessary reduction in chroma.
This is commonly produced by fuming the wood with ammonia. The hue may however be closely duplicated by a mixture of brilliant scarlet, metanil yellow, and nigrosene. It is practically the same as Flemish oak, but possesses one-quarter more color as can be seen on the orange hue rectangle.
The circle D shows this stain to be slightly below yellow green, ¾M, in value and chroma. The hue rectangle containing it is nearer the green than the orange yellow rectangle; hence in mixing the stain we should keep the green hue dominant by adding more of it than of metanil yellow. As in other stains, nigrosene is added to reduce the full chromatic intensities of the aniline to the proper value and chroma of olive green stain.
This stain is practically blue, 1/4M, and is formed by thinning nigrosene to the proper value.
Aniline dyes are apt to fade if exposed to full sunlight. There are, however, certain preventives that are beyond the scope of this book to treat in detail. The natural color of the wood is inclined to make a stain warmer than when originally mixed. This should be allowed for. Wood filler, the wood grain, porosity, qualities, and hue of the wood, all influence the final value of the stain. It frequently becomes darker in value as may be seen by comparing Figure 456 and Figures 458 to 461. It is good policy to test the stain upon different woods to observe the final effect. The tests may be kept for future reference.
It is readily seen from the few examples in Figure 456 that, with the three basic stains, almost any other stains may be produced, thus affording a broad field for harmonious selection and adaptation to the environment. The next chapters will take up the question of color harmony and its application to wood, wall surfaces, clay, and metal.
SUGGESTED PROBLEMS
See paragraph upon "Technical Practice" in this chapter, page 198.
REVIEW QUESTIONS
1. What pigments are best adapted to rendering design problems? What pigments are particularly adapted to the rendering of wood stains? How should each be applied?
2. What are standard hues? Why do we need standards of hue?
3. Define the term values.
4. What are tints and shades?
5. Define fully the term chroma.
6. Bound the hue rectangle and trace the value and chroma changes occurring on its vertical and horizontal lines.
7. Locate in its proper hue rectangle (Figure 455) the following hues: OY ¾HD; YG ½LL; RV ¾M; YL.
8. Name the three primary hues. How may an approximate scale of twelve hues be prepared from them?
9. Name the three basic aniline wood dyes and give their relation to the three primary hues. What is the practical use of nigrosene in stain mixing?
10. Give the symbol and explain the method of mixing Flemish oak wood stain. Name and explain the method of mixing two others.
11. How does its application to wood effect the color and value of aniline stain?
Plate 64
In the preceding chapter, the classification and standardization of color were emphasized as preliminary to the study of color harmony. Color harmony is obtained by the proper balancing of value, hue, and chroma upon a surface or surfaces to give a pleasing reaction to the eye, and through the eye to the intellect.
We are now ready to familiarize ourselves with the specific applications of these factors to practical design problems. Too many pieces of furniture are stained with no thought as to the final adaptation in the school or home. This is not wise, either from the standpoint of a complete educative process or of good taste. Figures 458, 459, 460, 461, show stains of Plate 64 applied to wood. Two new stains have been added, sage green and silver gray. These six stains are representative ones and act as a typical data for study of color harmony.
The side walls of a room form the background for furniture; trim, wall brackets, and similarly related objects; therefore the closest relation and harmony should be maintained between them.
The wood stains 3, 6, 9, 12, 15, and 18, Plate 65, as they appear on various kinds of wood are, in part, duplicates of the unapplied stains of Plate 64, Figure 456. The effect of the wood has changed their values and in some instances their color as can be seen by comparing the two plates. Their new relations have been plotted on the hue rectangles of Figure 457, Plate 65, and the results joined by a dotted line. The circles in the diagrams contain cross reference figures in order that the stains may be traced without difficulty. The highest value is near middle (18), and the lowest is low dark (6), showing a value range of four steps.
The side walls, taken from well-known wall tint catalogs have been similarly plotted in Figure 457, and the results joined together by a heavy black line. The lightest value is light (11), and the darkest is middle value (14), an average range of three steps slightly above middle value.
Ceilings are the lightest of the surfaces considered. Their range is from slightly below white (10), to light (16), a range of two values. From the results, as plotted in Figure 457, it is seen that there is a tendency to keep the ceilings within a close range of values. The results have been joined together by means of a double black line. There are exceptions to these results, but it is quite safe to keep well within the suggested range for harmonious results. We may now draw the following rules as a result of an empirical method of deduction.
Rule 12a. An average wood stain is to be retained between the values middle and low dark.
Rule 12b. An average wall hue is to be retained between the values light and middle.
Rule 12c. An average ceiling hue is to be retained between the values white (minus) and light.
Averaging the value range between the wood work which includes the furniture, trim, and the side walls of Figures 458, 459, 460, 461, 462, and 463, we find that the range varies from five values in Figures 459 to slightly more than one in Figure 463. As the side walls and furniture are to be regarded as unobtrusive settings for pictures and people it is well to be very conservative with the use of values. A wide range of values will cause a lack of unity. In this respect Figure 459 may be regarded as approaching the extreme limit of contrasts of value compatible with good taste. Let us, therefore, limit the value range to four values, as, for example: low light for side walls and dark for stain.
Rule 12d. The relation between the side walls and furniture, trim, etc., should be retained within the range of four values or less, as low light and dark.
The ceiling and side walls in Figure 459 are four values apart and in Figure 463 this has been reduced to a one-value step. There seems to be a common average of three values as an acceptable and agreeable contrast. For dark rooms this would well be increased. For rooms with light side walls the contrast would be considerably lessened.
Rule 12e. The relation between side walls and ceiling should be within the range of three values or less, as high light and low light.
A wood stain should be closely related to the natural color of the wood. As this is usually a warm color we naturally find most of the wood stains included between the red and the yellow hue rectangles, inclusive of red and yellow green. Walnut then may be stained a deep shade of orange or red, but would not be adapted to a blue green stain. This arbitrary but wide range of hues of stained wood naturally affects the hue of the side walls. The plotting of the hues for the side walls, Figure 457, shows a close relation to the hues of the stain to the wall. In no instance do we find the hue rectangle of the wood work more than three hues away from that of the walls. In four instances they are within two hue rectangles of each other and in one instance they are both within the same rectangle. This develops the fact that analogous or neighboring groupings of hues prevail in relating the hues of wood work and side walls.
An analogous group of hues is an arrangement based upon a selection of tints and shades within three rectangles of each other, as orange and yellow. These harmonize because yellow is mixed with and becomes a hue common to both. While the analogous arrangement of hues seems to be most commonly used, and with a result that seems to justify its adoption into general practice, there are other arrangements that are pleasing to the eye.
Figure 458 illustrates what is commonly known as a contrasted grouping or arrangement of hues. It consists of the tints or shades of one or more hues and gray. It is the basis of color harmony between silver and semi-precious stones. If two hues are used, one of them should be reduced in chroma to nearly gray.
Figure 463 is typical of still another form of positive hue grouping. By consulting the yellow hue rectangle of Figure 457 it is noted that the wood work, side walls, and ceiling of Figure 463 are all contained in one rectangle. This classes this color scheme as an example of dominant arrangement which may be simply defined as the tints and shades of one hue. The arrangement does not have the variety supplied by analogous grouping, introducing as it does, two hues from different rectangles, but for large surfaces dominant grouping is a conservative and safe arrangement. Its tendency toward monotony should be guarded against by the introduction of some object high in chroma in the room decorative scheme. A bright colored vase will accomplish this successfully. Rule 12o, Chapter XVII.
Rule 12f. Color schemes for wood work and side walls should preferably be selected from one of the following groupings: analogous, contrasted, or dominant arrangements of hues. Analogous grouping is preferable where variety of hue is desirable.
The above rule is not to be taken as arbitrary. In the hands of competent designers attractive color schemes are developed that differ materially from the above suggestions. But, for the usual home setting, the above arrangement may be regarded as satisfactory, and is given with the idea of bringing the school shop work and the home environment into closer color harmony. A specimen of special arrangement is given by the Circle 3A. This is delft blue, which harmonizes with dark mahogany in a satisfactory manner.
In adjusting the hues for side walls and ceilings, the relations should be of the closest. The plotting of ceiling hues in Figure 457 shows a strong tendency for the ceiling to be colored with a tint of the side walls (dominant arrangement), or by a tint selected from the next rectangle (analogous arrangement). Yellow or yellow-green, very light and much reduced in chroma, seems to be the almost universal custom. This is due to the strongly light reflecting qualities of yellow.
Plate 65
Rule 12g. Ceilings should be colored by a lighter tint of the side walls or by a lighter tint of an analogous hue.
Stains, as they occupy a comparatively limited area in the room color scheme, are of their full chroma value or reduced to three-fourths chroma. In only one instance (18), Figure 463, do we find a reduction to one-fourth chroma, demanded by the nearly gray color scheme of the walls. We find it to be an established fact that small areas are capable of enrichment by colors of greater purity and higher chroma than larger surfaces. A silver pin may be designed to contain a stone of high brilliancy, but a wall surface has to be materially reduced in chroma to possess color harmony.
Rule 12h. Stains are usually not reduced to below three-fourths chromatic intensity. Nearly gray side walls, however, call for a reduction to one-fourth intensity.
As the walls occupy a large proportionate area of the color scheme of the room we find it necessary to reduce them in chroma in order to soften the glare of too brilliant colors. Figure 457 shows only one instance (14) of a hue unreduced in chroma. It is retained at the full chroma for that value on account of the brightness of the sage green wood stain. The other hues represented in the diagram are grayed or reduced in chroma from three-fourths to less than one-fourth, or to nearly neutral gray.
Rule 12i. Wall colors are usually reduced to three-fourths chroma to a minimum reduction of slightly less than one-fourth chroma.
The same tendency toward chromatic reduction is to be seen in ceilings, although we have two examples in Figure 457 (10 and 13) of nearly white and high light ceilings that have not been reduced. To avoid crudity a reduction in chroma by the addition of gray is to be desired.
Rule 12j. Ceilings should usually be reduced in chroma to three-fourths intensity with slightly less than one-fourth chroma as a minimum reduction.
With a single exception (3A), the stains and wall tints have been selected between and including the red and green rectangles. This is customary and gives safe hue range as it insures the retention of wall and ceiling hues in unified conformity with the warm tints of the natural wood and its equally dark hued stains.
The following is a list of dry colors which may be purchased at a paint or hardware store for a few cents a pound. It is suggested for the designer or craftsman who desires to tint his own wall or ceiling. While oil paint is to be preferred, these colors are readily and quickly applied and form serviceable backgrounds.
The pigments are white, yellow ochre, chrome yellow light, chrome yellow medium, and chrome yellow dark, burnt and raw sienna, turkey and raw umber, ultramarine and ivory black. The greens are preferably mixed by adding ultramarine to one of the chromes. Shades are formed by the addition of the siennas, umbers, or black. Black and white, mixed to a gray, are useful in reducing the chroma of a hue. The stains should be mixed with hot water and a small amount of glue for a binder. White occasionally comes prepared with glue in its composition.
While this chapter has emphasized the transparent finish for wood treatment, as a method best fitted for woods with a distinct grain, it is realized that oil painting of wood surfaces has a distinct and important part to play in the interior decorative scheme of a room. This latter method is adapted to soft woods without a strongly marked grained surface. The warm hued rectangle of the spectrum: red, orange, and yellow with their associated hues, which are so intimately connected with the natural wood colors and their stains, no longer stand as a limiting factor in controlling the color of the wood or the side walls. The opaque nature of oil paints allows us to disregard the color of the wood, and thus select any hue of oil paint which harmonizes with the walls and decorative scheme of the room. The rules stated herein are equally applicable to opaque colors. It may be necessary to reduce oil paints in chroma beyond the point indicated in Rule 12h.
While it is not within the scope of this chapter to enter into a complete discussion of the subject of interior decoration, the following suggestions are considered as applying to our subject: viz., the surface enrichment of large areas. Complete color harmony in interior decoration generally demands the presence of the three so-called primary hues: red, yellow, and blue, in some form in the wall color scheme. While this is not always possible, two may be introduced as follows.
The light from the north, northeast, or northwest is cold blue, supplying blue in the decorative scheme of three primary colors: blue, red, and yellow. The wall tints should then be composed of combinations of red and yellow, the remaining primaries. These may be applied to the walls by means of tints of yellow and orange reduced in chroma, or shades of orange and orange-red. No greens or blues should be used.
The light from the south, southeast, and southwest supplies plenty of yellow. It is, then, necessary to add the remaining primaries or at least one of them in the form of gray-blue, orange, or orange-yellow, reduced to one-fourth chroma and practically to neutrality or grayish-reds and greens, well reduced in chroma. Any hue strongly yellow should be avoided.
Certain hues materially affect the apparent size of a room. If the room is small certain values and hues will make it appear much smaller. Dark values, as a rule, make the room look smaller by seemingly drawing the walls closer together. Red contracts the apparent size of a room, while yellow and blue expand it. Green and shades of yellow and red-orange, if not too dark, have little effect upon the apparent size of a room.
SUMMARY OF DESIGN STEPS
(a) Determine, by its exposure, the kind of light the room receives.
(b) Choose a hue for the walls embodying one or both of the primary hues not represented by this daylight.
(c) Select a value and chroma for this hue in accordance with Rules 12b and 12i.
(d) Select a hue, value, and chroma for the ceiling in accordance with Rules 12g, 12e, and 12j.
(e) Select the correct hue, value, and chroma for paint or stain for the wood work in accordance with Rules 12f, 12a, and 12h.
SUGGESTED PROBLEMS
Develop the color scheme for the walls, ceiling, and wood work of a room with a northern exposure; southern exposure. Mix the stain for a piece of oak to harmonize with the wood work and walls of the living room of your home.
Determine the wall tints to harmonize with dark weathered oak. Mix them from dry colors.
SUMMARY OF RULES
Rule 12a. An average wood stain is to be retained between the values middle and low dark.
Rule 12b. An average wall hue is to be retained between the values light and middle.
Rule 12c. An average ceiling hue is to be retained between the values white (minus) and light.
Rule 12d. The relation between the side walls and furniture, trim, etc., should be retained within the range of four values or less, as low light and dark.
Rule 12e. The relation between the side walls and ceiling should be within the range of three values or less, as high light and low light.
Rule 12f. Color schemes for wood work and side walls should preferably be selected from one of the following groupings: analogous, contrasted, or dominant arrangements of hues. Analogous grouping is preferable where variety of hue is desirable.
Rule 12g. Ceilings should be colored by a lighter tint of the side walls or by a lighter tint of an analogous hue.
Rule 12h. Stains are usually not reduced to below three-fourths chromatic intensity. Nearly gray side walls, however, call for a reduction to one-fourth intensity.
Rule 12i. Wall colors are usually reduced to three-fourths chroma to a minimum reduction of slightly less than one-fourth chroma.
Rule 12j. Ceilings should usually be reduced in chroma to three-fourths intensity, with slightly less than one-fourth chroma as a minimum reduction.
REVIEW QUESTIONS
1. What should we have in mind when staining furniture for the home?
2. Why are the side walls important when considering the color scheme of a room?
3. Give the value range for the average wood stains, side walls, and ceiling.
4. State the value range to include wood work, furniture, trim, and side walls.
5. State the value range that includes side walls and ceilings.
6. Give the hue range for wood work and side walls.
7. Explain the analogous, contrasted, and dominant groupings of hues and name two examples of each.
8. Give the hue range for side walls and ceilings. Name several good combinations.
9. Give range of chroma for wood work, side walls, and ceiling. Explain the reasons for each change of chroma.
10. What experience have you had in mixing calcimine for wall decoration?
11. Discuss opaque finishes for wood.
12. Give the hues for rooms with northern and southern exposures. Why?
13. State the effect of hues upon the apparent size of a room.
Before proceeding to the discussion of the application of color to clay it becomes necessary to determine what technical possibilities are presented.
Plain glazing of the entire surface is a common form of pottery enrichment. A piece of ware, thus glazed, may become a point of concentration in the color arrangement of a room, and should be definitely located in that arrangement. The ware may harmonize with the background (side wall) by analogy, dominance, or contrast or through complementary coloring. Rule 12o. A glaze from the diagram in Figure 464 should be selected as forming a part in the selected arrangement. Side wall (11), Figure 457, would harmonize with glaze C9 by virtue of its dominant relation or with M7 through analogy. The glaze selected should be higher in chroma than the side wall and will be found to form a cheerful and brilliant element in the room color scheme. The definite linking of these different factors of interior decoration into unity has been earnestly advocated in these chapters. Figures 457 and 464 show the possibilities of cross references.
It soon becomes apparent because of the coloring of clay ware that the designer must know something of the color possibilities of glazed pottery forms. The decorative processes were explained at some length in Chapter XII, wherein we described the common types of surface enrichment. As we are now primarily considering the question of color, we first regard the ware as uniformly glazed with either clear or matt glaze. The former is brilliant, of high chroma, and has a highly polished surface, while the latter is dull surfaced glaze of lower chroma.
Metallic oxides are used to stain or color clear glazes, while underglaze colors are ordinarily used for matts. The percentage of stains to be added to the dry glazes is stated in Figure 464 where they can be readily traced to their approximate locations in the hue rectangles by the reference letters M1, C1, etc. Certain oxides are weak coloring agents and require larger amounts of oxide to color the glaze perceptibly.
Iron and copper oxide may be mixed to produce a large variety of yellow greens; other combinations will suggest themselves. It is possible to use oxides as well as underglaze colors for staining matt glazes.
We have, to this point, considered the enrichment of large surfaces whose areas were arbitrarily determined by construction, as, for example, the extent of wall surface, ceiling, or wood trim and furniture. The essential element in this type of problem is the selection of a one, two, or three-hued color arrangement that would harmoniously link ceiling, wall, and wood together. If we had introduced stencilling or figured wall paper it would have immediately called for the solution of another problem, the factor of how much strong color to use. In other words, it would have introduced the question of proportionate distribution of color upon a given area. It was thought best to limit the subject of proportionate distribution to small areas, where the designer is often forced to make decisions and to divide surfaces into proportionate color parts for his surface enrichment.
We may now repeat the definition of harmony with the accentuation placed upon a certain wording directly applicable to small surfaces. Harmony is obtained by the proper balancing and proportionate distribution of value, hue, and chroma upon a surface to give a unified and pleasing reaction to the eye and intellect.
Rule 12k. Proportionate distribution of hue, value, and chroma in surface enrichment calls for a small area, high in chroma, and contrasting in value to the rest of the surface but harmonizing with it. This is usually located in the area of concentration. The larger areas are to be sufficiently reduced in chroma and value to form a slight contrast with the background.
Figure 465 illustrates some of the salient factors of distribution of values and hues. Hues of or near standard chromatic intensity should be used in small quantities and should accentuate the point of concentration. These small areas are to be regarded as giving brilliancy and life to the surface and to hold the eye at the point of concentration. Very small surfaces are capable of sustaining spots of high chroma, as is shown in the silver pin of Figure 468. The remaining portions of the surface enrichment should be kept subordinated in hue and value to the point of concentration, but related to it. The bands of Figure 465 are well reduced in value and make little contrast with the background, thus forming true surface enrichment or that which neither rises above or apparently falls through the surface. The point of concentration is higher in chroma than the surrounding areas.
Rule 12l. One hue, or a group of analogous hues should dominate all color schemes. The point of concentration may be emphasized by one hue related to the other hues by (1) contrasted, (2) dominant, (3) analogous, (4) complementary relations. This hue should make slightly stronger value and chroma contrast than the remaining hues.
Rule 12m. An extreme range of five values is generally sufficient to supply contrast to a design but still retain its value unity. Restraint in the use of values is essential.
Rule 12n. The amount of chroma may be increased in proportion to the decrease in the decorated area. Exceptions may be made to this under Rule 12o.
In the vase, Figure 464A, the designer selected hues from neighboring or analogous rectangles green and blue-green. The value range is restricted to four steps and the areas of concentration are placed at the top of the vase by the stronger value and hue contrasts of the foliage of the trees and dark blue rim. In both Figures, 464A and 465, the designer has used analogous hue arrangements. This is suggested to the beginner as serviceable for objects exceeding the dimensions of jewelry and includes such problems as vase forms, book stalls, and brackets. Contrasted and dominant arrangements are also good, safe, and sound arrangements, but fail to give the variety of color to small objects afforded by analogous grouping. At a later point in this chapter the subject of complementary coloring will suggest a new arrangement to the reader, but this scheme is to be left until he has sufficiently mastered the possibilities of the arrangements just indicated.
Five values form a safe value range for small objects. It is good practice to keep the larger areas, including the background, within three steps of each other and to allow the point of concentration to form the strongest value contrast.
The chroma may range from full to three-quarters intensity. Reduction to one-half or one-fourth intensity is inclined to make a small object appear washed out or chalky. Shades, at their full intensity, are good colors to use for small surfaces in wood. Small enameled objects may be developed in full chroma, while pottery forms range from full chroma to one-half chroma in forms of slip and underglaze painting.
It is interesting to note the gradually increasing chroma percentage of the different coloring media in direct proportion to the reduction of the area of the surface to be enriched. By comparing the diagrams of Figures 464 and 457 it will be seen that there is a steady movement toward the left sides of the hue rectangles or toward stronger intensity. The wall areas are shown to be lowest in chroma, followed by the increasing intensity of wood stains, glazes, and enamels.
Enamels, commonly used to enrich metal surfaces, are highest in chroma of the decorative materials under discussion and are to be treated with nearly as much restraint as one would use in enriching a surface with semi-precious stones, for strong hues are cheapened by excessive use. The plate in Figure 436 has small circles filled with enamel and a large field of chased or uncolored design.