Alizarine Dyes.

Scientific American Supplement 530, 27.2.1886

Notwithstanding the unprecedented progress of the coal-tar dyestuff industry during the past few decades, the time-honored indigo, logwood, fustic, etc., have been only partly displaced by the coal-tar products in wool dyeing. The cause is that, though the dyer handled many aniline dyestuffs which dyed as fast against light as logwood or fustic, the dye proved unsatisfactory for fulling goods, because it bled in the treatment with soap and soda, and often more or less changed its tone. We intend to render a service to our readers by calling their special attention to some products of the coal-tar industry which are free from these defects of aniline dyestuffs, and for which it is claimed that they far surpass logwood, fustic, cudbear, etc., as to fastness against light, and excellently stand fulling. We allude to the alizarine dyestuffs, which have long since been introduced and are largely employed in cotton dyeing and printing.

Alizarine, which has been extensively discussed in various articles in our journal, is the coloring matter contained in the madder root. In 1869, two German chemists, Graebe and Liebermann, succeeded in artificially producing this dyestuff from anthracene, a component of coal-tar. The artificial dyestuff being perfectly pure and free from those contaminations which render the use of madder difficult, it soon was preferred to the latter, which it has at present nearly completely displaced.

The discovery of alizarine red was soon followed by those of alizarine orange, galleine, coeruleine, and, in 1878, of alizarine blue.

The slow adoption of these dyestuffs in the wool-dyeing industry is principally attributable to the deep-rooted distrust of wool dyers against any innovation. This resistance, however, is speedily disappearing, as every manufacturer and dyer trying the new dyestuffs invariably finds that they are in no respect inferior to his fastest dyes produced with indigo and madder, but are simpler to apply and more advantageous for wool.

The alizarine colors are dyed after an old method which is known to every wool dyer. The wool is first boiled for 1½ hours with chromate of potash and tartar, then dyed upon a fresh bath by 2½ to 3 hours' boiling. All alizarine colors (such as those of the Badische Anilin und Soda Fabrik, of Ludwigshafen and Stuttgart; Wm. Pickhardt & Kuttroff, New York, Boston, and Philadelphia, viz.):
Alizarine orange W, for brown orange,
Alizarine red WR, for yellow touch ponceau or scarlet,
Alizarine red WB, for blue touch yellow or scarlet,
Alizarine blue WX and SW, for bright blue,
Alizarine blue WR SRW, for dark reddish blue,
Coeruleine W and SW, for green, and
Galleine W, for dahlia,
are dyed after the same method, which offers the great advantage that all these colors can be dyed upon one bath, and that by their mixture numerous fast colors can be produced. On the ground of numerous careful experiments, the writer recommends the following method, which gives well developed and well fixed colors, viz.:
For 100 kil.
The scoured and washed wool is mordanted by boiling for 1½ hours in a bath containing 3 kil. chromate of potash and 2½ kil. tartar, and lightly rinsed; when it can immediately be dyed. For 1,000 lit. water, 1 lit. acetic acid of about 7 deg. Be. is added to the bath. If the water is very hard, double the quantity of acetic acid, which is indispensable, is added. Then the required quantity of dyestuff is added, well stirred, the wool entered, and the temperature raised to boiling, which is continued for 2½ to 3 hours, that is, until a sample taken does no longer surrender any color to a hot solution of soap. Loose wool and worsted slubbing can be entered at 60 deg. C. (140 deg. F.). In dyeing yarn and piece-goods, however, it is advisable to enter the bath cold, work for about ¼ hour in the cold, and then slowly to raise the temperature in about one hour to the boiling point. With this precaution, level and thoroughly dyed goods are always obtained. If the wool is entered in a hot bath, or if it is rapidly brought to a boil, the dyestuff is too rapidly fixed by the mordant and is liable to run up unevenly, and, with piece-goods, more superficially. For the same reason the goods must always be well wetted out before entering the bath.

We add some special recipes for the various colors, the mordant for all of them being of 3 per cent. chromate of potash and 2½ per cent. tartar for 100 by weight of dry wool.

1. Orange, Brown Touch.
20 kil. wool, mordant with 600 grm. chromate of potash and 500 grm. tartar, dye with 3 kil. alizarine orange W.

2. Ponceau, Yellow Touch.
20 kil. wool, mordant as for No. 1, dye with 2 kil. alizarine red WR 20 per cent.

3. Ponceau, Blue Touch.
20 kil. wool, mordant like No. 1, dye with 2 kil. alizarine red WB 20 per cent.

4. Dahlia.
20 kil. wool, mordant like No. 1, dye with 5 kil. galleine W.

5. Green.
20 kil. wool, mordant like No. 1, dye with 6 kil. coeruleine W.

For Piece-goods.
20 kil cloth, mordant the same, dye with 1 kil. 200 grm. coeruleine SW.

6. Blue, Bright.
20 kil. wool, mordant the same, dye with 6 kil. alizarine blue WX.

For Piece-goods.
20 kil. cloth, mordant the same, dye with 1 kil. 200 grm. alizarine blue SW.

7. Blue, Dark and Red Touch.
20 kil. wool, mordant like No. 1, dye with 6 kil. alizarine blue WR.

For Piece-goods.
20 kil. cloth, mordant the same, dye with 1 kil. 200 grm. alizarine blue SRW.

Particular stress is to be laid upon the great fastness of the alizarine dyes against light and fulling. Besides, these dyestuffs contain nothing whatever injurious to the wool fiber. Sanders, which very much tenders the wool, as every dyer knows, can in all cases be replaced by alizarine red and alizarine orange, making an end to the spinners' frequent complaints about too much waste.

Alizarine blue in particular seems to be destined to replace indigo in the majority of its applications, having at least the same power of resisting light and acids, and relieving the dyer of the troublesome, protracted rinsings required for indigo dyed goods. Every piece-dyer knows that the medium and dark indigo blue goods still rub off, even after eight hours' rinsing; but alizarine blue pieces are perfectly dyed through and clean after one hour of rinsing. Another advantage of alizarine blue and the other alizarine dyestuffs is that they unite with all wood colors, as well as with indigo carmine and all aniline dyestuffs. A fine and cheap dark blue, for instance, is obtained by mordanting the wool as above stated and dyeing (20 kil.) in the second bath with 6 kil. alizarine WX and 2 kil. logwood chips; the wood is added to the bath together with the alizarine blue WX, and the best method is to put it into a bag which is hung in the bath.

- D. Woll.-Gew.; Tex.Colorist.

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