The Dyeing of Woollen Fabrics Part 15

_Light Green_.--Mordant in the usual way with 2-1/2 lb. bichromate of potash and 2 lb. tartar. Dye with 1 lb. Methylene Blue and 1 lb.

fustic extract, working at the boil.

_Fast Green_.--Mordant with 8 lb. alum, 2 lb. bichromate of potash, 2 lb. sulphuric acid and 3/4 lb. tin salt. Dye with 20 lb. indigo (p. 134) extract and 10 oz. fustic extract, working at the boil for one and a half hours.

_Bottle Green_.--Mordant with 3 lb. bichromate of potash and 2-1/2 lb.

tartar. Dye with 4 lb. extract of fustic, 1 lb. extract of logwood, and 2 oz. Anthracene Red. Work for one and a half hours, then add 3/4 lb. copperas, and work for half an hour longer.

_Dark Green_.--Mordant with 3 lb. bichromate of potash and 2-1/2 lb.

tartar. Dye with 1-1/2 lb. Methylene Blue, 1-1/2 lb. extract of logwood, and 4 lb. extract of fustic, working at the boil for two hours.

_Olive_.--Prepare a dye-bath with 1-1/2 lb. Yellow N, 1/4 lb. Archil Subst.i.tute, 4 lb. extract of indigo, 10 lb. Glauber's salt, 2 lb.

sulphuric acid, and 2 lb. alum, working at the boil to shade.

_Bright Green_.--Prepare a dye-bath containing 8 oz. Acid Green Extra and 10 per cent. bisulphate of soda. Enter at 130 F., raise to the boil, boil for three-quarters of an hour, and rinse.

_Bluish Green_.--Prepare a dye-bath containing 8 oz. Fast Acid Green B N and 10 lb. bisulphate of soda. Enter at 130 F., raise to the boil, boil for three-quarters of an hour, and rinse.

_Bluish Green_.--Prepare a dye-bath containing 8 oz. Cyanole Green 6 G and 10 lb. bisulphate of soda. Enter at 130 F., raise to the boil, boil for three-quarters of an hour, and rinse.

_Turquoise Green_.--Prepare a dye-bath containing 8 oz. Cyanole Green B and 10 lb. bisulphate of soda. Enter at 130 F., raise to the boil, boil for three-quarters of an hour, and rinse.

_Slate Green_.--Mordant the wool by boiling for one and a half (p. 135) hours in a bath containing 3 lb. bichromate of potash, 1-1/4 lb.

Copper sulphate and 2-1/4 lb. tartar; then rinse well, and dye in a bath containing 2-1/2 lb. Logwood Extract (dry), 1-1/4 lb. Fustic Extract (dry), and 3 lb. Sumac. Enter the goods in a warm bath, work for half an hour, then raise to the boil and work for three-quarters of an hour; lift, and sadden by adding 6 oz. Copperas. After re-entering the goods, work to shade.

_Olive_.--Boil two hours in a bath consisting of 1-1/2 lb. tin salt, 2-1/2 lb. bichromate of potash, 10 lb. alum and 2-1/2 lb. sulphuric acid. Then enter in a boiling dye-bath containing 1-1/2 lb. alum, 4 lb. fustic extract and 3-1/2 lb. indigo extract.

_Fulling Fast Olive_.--For one hour upon a bath containing 50 lb.

Fustic, 5 lb. Bluestone, 2 lb. Tartar, 4 lb. Sumac, 1 lb. Copperas; lift and wash.

_Fast Bright Olive_.--Boil for one hour upon a bath of 50 lb. Fustic, 3 lb. Bluestone, 2 lb. tartar, 1 lb. copperas, 2 oz. indigo extract.

_Yellow Olive_.--Prepare a bath containing 10 lb. Glauber's salt, 1-1/2 lb. Anthracene Yellow B N, 2 lb. extract of indigo, 3 oz. Orange E N Z, 4 lb. sulphuric acid. Enter yarn at 160 F., give three turns, raise the temperature slowly to the boil, turn to shade; lift, and wash.

_Olive Green_.--Mordant with 2 lb. potash bichromate, 1-1/2 lb.

sulphate of copper, 1/2 lb. sulphuric acid. Boil for an hour and a half. Dye in a bath with 8 lb. Fustic extract, 5 lb. Sumac, 5 lb.

Logwood, at the boil for an hour and a half.

_Olive Bronze_.--Make the dye-bath with 10 oz. Fast Yellow S, 5 lb.

Indigo extract, 5 oz. Orange E N Z, 4 lb. sulphuric acid, 10 lb.

Glauber's salt. Enter yarn at 140 F., work for a few minutes, then bring slowly to the boil and work to shade.

_Emerald Green_.--Prepare the dye-bath with 1 lb. Acid Green B N, (p. 136) 2 oz. Naphthol Yellow S, 10 lb. Glauber's salt, 2 lb. sulphuric acid. Enter cold, then raise to the boil and work for a quarter of an hour; wash and dry.

_Invisible Green_.--First mordant the wool in a bath containing 3 lb.

bichromate of potash, 1-1/2 lb. copper sulphate, 1 lb. sulphuric acid.

Work at the boil for one and a half hours, then dye in a fresh bath containing 2 lb. Milling Yellow O, 2 lb. Logwood extract, 20 lb.

Glauber's salt. Work at the boil for one and a half hours, then lift, wash and dry.

_Sea Green_.--Prepare a dye-bath with 5 lb. Glauber's salt, 2 lb.

sulphuric acid, 2 lb. indigo extract, 1/2 per cent. Acid Green blue shade. Dye as usual.

Cyprus Green B, and Cyprus Blue B, belong to a new group of dyes that owe their value in wool dyeing to the fact that the dyeings after being treated with copper sulphate become very fast to light and washing. Three per cent. of each gives very full shades of bluish green or dark blue. The dyeing is done with Glauber's salt and acetic acid when reddish shades are got; these in a bath of copper sulphate turn green or blue.

BLUE SHADES ON WOOL.

There are a very large number of blue artificial dyes of every cla.s.s, but only a few natural ones, indigo and logwood, and with these every imaginable tint and shade of blue from the palest sky tints to the darkest navy blue or blue black can be produced.

While some of the blue colouring matters possess no great powers of resistance to light, air, washing, etc., the great majority are remarkable for their fastness to those destructive agencies.

There are but two natural dye-stuffs, indigo and logwood, from which blue tints can be dyed. With the former, a great variety of shades can be dyed of a satisfactory character as regards fastness; with the (p. 137) latter, only dark blues can be dyed, these are fairly fast to milling, but only moderately so to light.

The artificial blues derived from coal tar are very numerous, and representatives of all cla.s.ses, direct, basic, acid and mordant of dye-stuffs may be found among them. The direct blue dyes do not work very well on wool. They are apt to dye very red, and somewhat dull shades, which are, however, fairly fast to washing and light. The basic blue dyes are fairly numerous, and may be used to dye from pale sky to deep navy tints. They are apt to work somewhat unevenly on to wool, owing to their great affinity for the fibre. They give shades possessing some degree of resistance to light, but which are not very fast to washing and milling, although, in this respect, there are very great differences among them. The acid dyeing blues are fairly numerous, but they dye a great variety of tints, usually fairly fast to washing, milling and light. The mordant blues are pretty numerous and of great value for dyeing wool, as they give shades which are remarkable for their fastness to light, acids and milling, hence they are most extensively used, especially for dyeing fabrics that are subject to very hard wear.

#Indigo Dyeing.#--It will be most convenient to begin the description of the methods of dyeing blues by showing how, and in what manner, indigo is applied in wool dyeing.

The dyeing of indigo on wool is effected in two ways, either in the usual way with acid baths, as with acid scarlets, when the so-called indigo extract is used, or in vats, when indigo itself forms the dye-stuff.

Indigo is, as all dyers know, or should know, a natural dye-stuff, prepared from the leaves and twigs of the indigo plant by a species of fermentation which produces the indigo in a soluble form from the indigo substance in the plant, followed by oxidation which results in the separation of the indigo from this solution.

It comes into this country in the form of lumps, which have a dark (p. 138) blue to bronze blue colour. The dye-stuff is insoluble in water, cold alcohol, alkalies or weak acids. When heated with strong and fuming sulphuric acid it dissolves, forming a blue liquor from which the colouring matter may be obtained on addition of soda in the form of a paste, which is used in wool and silk dyeing under the name of indigo extract. But dissolving in sulphuric acid materially affects the properties of indigo as a dye-stuff, as will be seen later on.

By the action of reducing agents the insoluble blue indigo is converted into a soluble white indigo. This body is rather unstable, and on exposure to the air it rapidly becomes oxidised and converted back again into the blue indigo. Upon this principle is based the application of indigo in dyeing by means of the vat.

Various methods may be adopted to cause the indigo to become dissolved. These may be divided into two groups: (1) Fermentation vats, in which the action of reducing agents is brought about through the influences of the fermentation of organic bodies, such as woad, bran, treacle, etc; (2) Chemical vats in which the reducing effect is brought about by the reaction of various agents on one another.

Of such vats the copperas and lime and the hydrosulphite vats are examples. The fermentation vats, when in good order, work well and give good results, but they are most difficult to prepare or set. The chemical vats are the easiest to work, and (especially the hydrosulphite vats) are coming to the fore, and are gradually driving out the fermentation vats.

The actual method of dyeing with the indigo vat is the same with all methods of preparation. The material to be dyed is well wetted or wrung out in water. It is then dipped into the vat, handled a few minutes to ensure its thorough impregnation, then lifted out, the surplus liquor wrung out, and the material exposed to the air, (p. 139) when the indigo white on it soon absorbs oxygen and turns into blue indigo.

With these few preliminary remarks the methods of setting the various indigo vats will now be described in detail.

#Woad Indigo Vats.#--This is one of the most difficult of the various methods of setting vats. There are so many opportunities for it to go wrong, and to be able to set a woad vat successfully will go far to make a man a successful indigo dyer. No two woad vat dyers use exactly the same recipe in setting a woad vat, and each considers he has a secret art by means of which he ensures the successful working of this vat, and this he jealously guards. All these differences in the manner of setting the vat are brought about not by any radical differences in the materials used, but by some unnoticed differences in other surroundings; differences in the mean temperature of the water used, in the general conditions of the atmosphere of the indigo shed and in other similar circ.u.mstances, all of which have a material influence on the development of the vat, but which are, in the majority of cases, overlooked by the indigo dyer, the result being that a method of working which is successful in one place would not be so in another.

The fermentation processes depend upon the reducing action brought about by certain organisms of the nature of the yeast plant which grow and develop in such vats.

To ensure the proper growth and development of these organisms every condition must be perfect, correct temperature, proper proportions of food for them to live on, and a certain degree of alkalinity or acidity of the vat, and these points are most difficult to regulate as they will vary very much from time to time.

A successful vat maker is one who closely observes his vats, and the way in which they are working, and who, as the result of such (p. 140) observations, is able to tell in what way his vats are deficient, so that he may know how to supply that deficiency.

The following method of setting a woad vat may be adopted. It is calculated for 100 gallons of liquor. The vat is filled with hot water, and 80 lb. of woad are allowed to steep overnight in it, having first been well stirred into the water, so as to ensure that every part is wetted out. The next morning there is added 8 lb. madder, 12 lb. bran, 5 lb. quick-lime (previously slaked with water), and 2-1/2 lb. soda. These are thoroughly stirred together, then from 5 to 7-1/2 lb. indigo is stirred in. The indigo should have been previously ground into a fine paste with water. The temperature of the vat should now be maintained at from 115 to 125 F. for two to three days, at the end of which time it ought to be in a state of quiet working.

Should it be found that the fermentation is going on too rapidly, a little lime may be thrown in, which will r.e.t.a.r.d it. On the other hand, if it should not be going on with sufficient energy, this may be remedied by adding a little bran, or better, a little treacle.

When in perfect condition the vat should have a slight smell of ammonia. If this is not noticed it indicates that the vat is deficient in alkalinity, and a little more lime should be added. Soda may be used in the place of lime, but it is so much more energetic in character that any additions of it have to be made with great care, or the vat will become too alkaline in character, and the fermentation will go on too rapidly, the ammoniacal odour is lost, and a peculiar putrid smell takes its place. As soon as this is noticed, lime ought to be added to r.e.t.a.r.d the fermentation and to develop the ammoniacal smell. The colour of a good well-set vat is olive brown.

When all the indigo is dissolved and the colour of the vat is a (p. 141) clear olive yellow to brown the vat is then ready for dyeing, and may be used for a long time, until, in fact, the deposit gets too large and the wool becomes dirtied. But it must not be continually worked, or it will give bad shades and loose colours. When in a bad condition it will usually turn of a dark brown colour, and give dull greenish shades. To remedy this there should be added some bran, treacle, and a little madder, as well as indigo, and the vat should be left for a day, at a temperature of 130 F., to get up to full strength again. Every night when in work indigo ought to be added to the vat in proportion to that consumed during the day, with bran and lime, the latter in not too great amount, just sufficient to keep it of the necessary alkalinity.

#Hydrosulphite Vat.#--This is one of the best vats to use in dyeing with indigo on wool, or, indeed, on any textile fabric. It is easy to prepare and cleanly to work. While depending solely on chemical action for its preparation and use, it is freer from those peculiar defects to which organic vats, like the woad vats, are liable.