The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Coloring Finishing And Painting Wood
89. Patent Bark.—This is the name given to a product of quercitron, made by boiling the bark in dilute sulphuric acid, then drying and washing the residue.
90. Flavin, or Flavine.—A yellowish-brown dry extract of quercitron bark produces very bright yellow colors in dyeing. It is sometimes used with cochineal to make bright scarlet-yellow colors. Flavine is the form of quercitron that is listed among the dyestuffs on the New York market. Neither fustic nor quercitron produces colors as brilliant and fast to light as those obtained from certain mordant dyes of coal-tar origin.
Coal-Tab Dyes And Their Use As Wood-Stains
91. Characteristics and Origin.—Coal-tar, formerly considered an almost worthless waste product, is a very black, opaque, and thick mass, which is liquid at certain temperatures. It is formed through condensation from gas in pipes during the manufacture of coal-gas, and is, therefore, a distillate from coal. The first coal-tar dyes were pro-duced from aniline, which is one of the light tar-oil derivatives from nitrobenzene. Many other coal-tar dyes are de-rived, not from aniline, but from medium and heavy tar-oils, among these colors being many of the alizarine group.
In variety of tints and shades, and in brilliancy of hue, the coal-tar dyes are superior to all other dyestuffs. A French chemist is reported as having said that about 14,000 shades and tints of various hues can probably be made from coal-tar. Considerably less than one-tenth part of this number is now made and actually used. The exact number of colors listed in the "Color-Index" of the Society of Dyers and Colorists, is 1249.
The fugitive characteristic of many of the early coal-tar dyes has been overcome to a large extent. Chemically, some of these artificial dyes are practically the same as cor-responding natural dyes. For example, the renowned "Tyrian Purple" is now made synthetically, and is known as Dibromindigo.
92. All Coal-Tar Dyes Are Not Aniline Dyes.—The term aniline should not be applied to all of the synthetic coal-tar colors, because many of the dyes now manufactured are not made from aniline. Aniline is simply one of several derivatives from nitrobenzene, which is manufactured from light tar-oil. Many other coal-tar dyes are produced at present which are not related closely to aniline, but are made from other derivatives. The early basic dyes, such as Perkin's Mauve, Magenta, and Methyl Violet, were aniline dyes, while other colors came from coal-tar derivatives. To call all coal-tar dyes aniline dyes is misleading and wrong; nevertheless the term aniline is quite com-monly used in trade circles to designate all coal-tar dyes. Whether the term aniline dyes will finally be used as a general name for all coal-tar dyes we do not know at present. Chemists do not now so use the term.
