Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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1. The multiple phenomena of light, manifest in the appearance of objects and light sources that are specified and described totally in terms of a viewer's perceptions pertaining to hue, lightness, and saturation for physical objects, and hue, brightness, and saturation for sources of light. The normal human eye is sensitive to a range of wavelengths from approximately 3.8/10,000 to 7.6/10,000 mm., with the longest wavelength being perceived as red, followed in descending order by orange, yellow, green, blue, indigo and violet. These are called Newton's spectral colors, i.e., they are seen when a beam of sunlight is split into its component parts, as it passes through a prism. Notwithstanding this separation, however, a precise limit for any single color cannot be made because the spectrum undergoes a continuous transition throughout the series. If the human eye perceives all seven kinds of light in the spectrum, and in the same proportions, the "color" seen is white.

The color of a particular object is usually contingent on the white light striking the surface of the object and being completely or at least partially absorbed in the surface of the material, with the remaining light being reflected from it. Consequently, when a person sees the color "red," for example, it means that all of the incoming wavelengths (white light) have been absorbed by the surface of the object viewed except those wavelengths which constitute the color we have designated as red. If the light reflected from the surface of the object is allowed to pass through a further colored layer before reaching the eye, such as, for example, a transparent yellow film, more light will be absorbed, and the result will be a mixed color, i.e., orange. This process is called "subtractive color mixture," or color obtained by successively eliminating light of different wavelengths from white light.

Pigments, as well as dyes and inks, are mixed with one another to create new hues according to the subtractive system. In theory, any chromatic hue may be obtained by a mixture of the three primary colors. In practice, however, many hues can only be approximated by mixing primaries. See also: COOL COLORS ;FAST COLORS ;FUGITIVE COLORS ;WARM COLORS .

2. Pigment or aniline colors used on the edges of books or on endpapers for tinting or coloring purposes. 3. The suspension or slurry of the materials for use in the pigment coating of paper. (17 , 140 , 233 , 234 , 350 )

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