Industrial Arts Design Part 30

[Sidenote: Values and Horizontal Value Lines]

_Value_ is that quality by which we may distinguish a dark hue from a light one. For design purposes we will imagine the hue rectangle to grade from white at the top to black at the bottom. We will draw horizontal lines or steps across the rectangle, marking nine even value steps from white to black; the top one to be termed White (W), followed by High Light (HL); Light (L); Low Light (LL); Middle (M); High Dark (HD); Dark (D); Low Dark (LD); and Black (B). These value steps may be thought of as a scale of gray or neutral values descending the _right boundary_ of the hue rectangle. They have been roughly indicated in the hue rectangle at the left of Figure 454.

[Sidenote: Relation of the Standard Hue to the Hue Rectangle]

Each standard hue may now be located in the _left boundary_ of its hue rectangle and opposite its neutral gray equivalent in the right boundary. If the standard hue is accurately determined by the designer, it will be of exactly the same value as its gray equivalent given in the "value" column of the pigment table. The small arrows leading from Figure 455 to 454 show where four standard hues are located; the remaining hues are located in the left circle of each successive row in the remaining rectangles, and upon their respective value lines.

Standard hues are expressed by the symbols in the _right column_ of the pigment table.

[Sidenote: Tints]

Each standard pigment or hue may be thinned with opaque white to lighten it, forming what is known as a tint of that hue. Red, in Figure 454, reaching its full chromatic intensity at the value High Dark, may be lightened four times before it ultimately arrives at white. Each step is to be considered as occurring in the left hand boundary of the rectangle above the standard hue, and is to be recorded by the symbols, R-M: R-LL: R-L: R-HL. Orange yellow has only one possible tint. Strawberry, light lavender, rose, etc., are merely nicknames for various tints.

[Sidenote: Shades]

Each standard hue may be darkened by the application of black, thus forming shades of that hue. Red is capable of producing two shades, R-D and R-LD, which are placed in the left boundary of the hue rectangle below the standard hue. Browns, russets, and dark tans are shades of different hues.

These modifications of the standard hues into tints and shades give to the designer simple variations of his too brilliant standards. But even these modifications are not sufficiently grayed for staining or painting large wood or wall surfaces. There is a brilliancy and glare about certain tints which require modification. The shades are safer for use on large areas. The remaining s.p.a.ce in the interior of the hue rectangle is to be devoted to the last gradation of the standard hue.

[Sidenote: Chroma]

_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.

[Sidenote: Vertical Chroma Lines]

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 t.i.tle or symbol may now be written as follows: (1) hue name, (2) amount of chroma, (3) value. Examples: GB [Sidenote: Full Hue Symbols]

3/4D-V1/2HL. 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.

[Sidenote: Technical Practice]

[Sidenote: Warm and Cold Colors]

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.

[Sidenote: Scales of Color]

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.

[Sidenote: Wood Stains]

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.

[Sidenote: Basic Primary Hues]

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.

[Sidenote: Three Basic Aniline Wood Dyes]

Developing this idea further, we may select aniline brilliant scarlet as approximating red; metanil yellow, approximating yellow; and acid green as a subst.i.tute 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.

[Sidenote: Wood Stain Mixing]

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.

[Sidenote: Dark Mahogany Stain]

Dark mahogany stain in Figure 456 is orange red, HD, 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.

[Sidenote: Flemish Oak Stain]

Flemish oak stain is orange D. 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.

[Sidenote: Fumed Oak Stain]

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.

[Sidenote: Olive Green Stain]

The circle _D_ shows this stain to be slightly below yellow green, M, 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.

[Sidenote: Light Weathered Oak Stain]

This stain is practically blue, 1/4M, and is formed by thinning nigrosene to the proper value.

[Sidenote: Color Changes of the Stain]

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.

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