So, little by little, the knowledge of these natural dyestuffs and their application grew and expanded. But as a matter of fact, so far at least as can be gathered from the old writers, those known and used by the ancient Greeks and Romans were few in number and of comparatively little interest.
For blues they were obliged to use the inferior color derived, as above mentioned, from the native woad, excepting when, for some special purposes, a little indigo was imported from the East at enormous expense.
Their principal yellow dyestuff was saffron, which is derived from the flowers of the common yellow crocus. This gives pleasant, warm shades of golden yellow, not fast, however, to either light or washing. This same saffron, though long since entirely abandoned as a dyestuff, is still used in small quantities for staining candy and foodstuffs, and occasionally for medicinal purposes.
The ancients are believed to have discovered the dyeing properties of the roots of madder—rubia tinctorum—(the dyer’s root), and to have used it in small quantities for producing purple and brown and, possibly, even red shades, on cotton and wool. Whether, however, the art of dyeing the brilliant crimson and scarlet shades known as Turkey red was ever worked out before the Middle Ages, is extremely doubtful.
Animal Dyes.—Unquestionably the best red dyes known to the people of those early times were of animal origin, and were used for various shades of red and of purple.
Kermes.—One of these, called kermes, is very closely related to the more important and, up to a few years ago, the very generally used, cochineal, and to the lac dye.
These three dyestuffs—kermes, cochineal, and lac—come to the market in the form of little dark colored grains, which, when ground up with hot water, give a bright red solution called carmine, which contains a considerable amount of a coloring known as carminic acid. When wool or silk that has been previously mordanted—that is, impregnated with chemical agents; in this case salts of tin, aluminium, iron, or copper—is boiled in one of these solutions, it becomes scarlet, crimson, purple, or claret color, according to the mordant employed. From the appearance and form, as they come to market, of these dyestuffs, the shades thus derived are commonly known as the “grain colors.”
When these granules are soaked for some time in warm water they swell, and their true character becomes apparent. They consist of the dried bodies of small insects, known as “cocci” (berries), which are carefully cultivated on particular kinds of trees or shrubs and when full grown are brushed off and dried for market. They are very small—the cochineal grains, which are the most important, running about 70,000 to the pound.
Kermes, which was the only one of the three known to the old Greeks and Romans, consists of the dried bodies of the “coccus ilicis,” a variety of the insect which lives on a species of oak, and which, it is said, is still occasionally used in Southern Europe, and in Morocco, for dyeing leather and wool.
Tyrian Purple.—The most highly prized ancient dyestuff, and one concerning which much interest has always been felt, was the so-called “Tyrian purple.” This was obtained from the juices of certain species of snails found in the waters of the Mediterranean Sea, and, indeed, in the ocean waters of many other warm climates. Two species of this class—themurex Brandaris and themurex trunculus—were used extensively by the ancients, and great mounds of their shells, such for instance as the so-called Monte Testaccio at Tarentum, are still found along the shores at places famous, in old days, for their dyeing establishments.