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Adding Color to Our Lives
| Article
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13013 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
5 / 1987 |
3,583 Words |
| Author
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John J. Beer
John J. Beer is professor of the history of science at the
University of Delaware and has written a book entitled The
Emergence of the German Dye Industry. |
The beach sparkles with red, yellow, blue, and green. Swimsuits break the monotony of the sand's tan. The color of modern swimsuits remains unchanged under the onslaught of salty seawater, chlorine in swimming pools, the unrelenting ultraviolet rays of sunshine, perspiration, and acids. Science has triumphed over these and other obstacles to bring to our clothes and to much of our surroundings a vast variety of tints and tones that resist fading and other discoloration. We live in a world of hues of varieties unknown and perhaps unimagined by our ancestors.
Nature loves color, too. Many flowers, insects, fish, and birds are adorned in numerous shades. Humans have developed pigments and dyes that equal or surpass the range of nature's rainbow. Contemporary technology offers us choices from a wide spectrum of colors for our garments, upholstery, draperies, and other objects.
The economic and social impacts of modern color technology are colossal. Giant industries have blossomed forth from the development and manufacture of dyes. Colors increase sales of products as consumers select and purchase items of varying shades to complement their complexions and to match their belongings.
Pigments of mineral origin merely cover the surface of an object. Dyes obtained from plant or animal extracts penetrate and combine with materials, becoming an integral part of them.
Long before the invention of writing five thousand years ago, textiles made by interlacing fibers were in use on all continents. Wool and linen cloth probably originated in lands bordering the eastern Mediterranean. Cotton was first used in India. Silk came from China. These four natural fibers are still in use today and are joined by many synthetic fibers, but most of the natural dyes originally used for fibers were replaced a century ago by synthetic dyes.
Traditionally, dyes are classified according to their chemical structures and to the method of application. Direct or substantive dyes color fiber on contact. Mordant dyes require an auxiliary chemical to fix the color onto the fabric. Vat dyes are insoluble in water.
To apply them they must be changed chemically into a soluble leuco compound. Textiles immersed in such a bath become colored only after they have been withdrawn from the vat. Exposure to air or chemicals oxidizes the leuco compound to the desired dye deep inside
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