The _Dye Vat_ should contain about 10 gallons of water heated to hand hot, 120 and not above 140F. Add 3 ozs. of hydrosulphite solution stirring carefully, let it stand for 20 minutes; this renders harmless any undissolved oxygen. Add a small cupful of the Stock Solution, stir carefully without splashing. The vats should be greenish yellow and _should not feel slimy_, an indication of too much caustic. The vat is now ready to dye and is kept at 120 to 140F.

Between dips add Stock Solution as required, if the vat goes blue and turbid add 3 to 4 fluid ozs. of hydrosulphite and warm up to 140F.

and wait 30 minutes. As a last resort add caustic soda solution very gradually. This should not be required if the Stock Solution is properly prepared.

Start to dye with weak vats, 20 to 40 minute dips, and finish with stronger vats. The more dips given to obtain a fixed shade, the faster will be the yarn to washing and rubbing. The yarn must be oxidized by exposure to the air for the same length of time as dipped. After the final dip, pa.s.s the yarn through a 10 gallon bath of water to which is added 3 ozs. of sulphuric acid, pure or hydrochloric. This neutralizes the caustic used. Wash yarn at least twice in water.

_Improvement of Defective Indigo Vat Dyes._

If, after washing until clear, the yarn should rub off badly, there is but one remedy. Wash same in Fuller's earth, and if the shade is then too pale, re-dye. If, through bad management of the vats, the yarn is dull, pa.s.s the yarn through a hot bath (100% water, 1% acetic acid) and wash in two waters. If yarn is streaky, take 10 gallons of water at 120F., 1 oz. of hydrosulphite powder, 2 fluid ozs. liquid ammonia fort. 880, and let yarn lie in same for 60 minutes. Wash in two waters.

The following facts should be carefully noted:--

The Caustic Soda is the _alkali_ which dissolves the Indigo White.

The Hydrosulphite _reduces_ the Indigotine in the Indigo to _Indigo White_.

Indigo White is fixed on the yarn as Indigo White and on exposure to the air becomes blue.

The yarn, on removal from the vat, should come out greenish yellow or a greenish blue. The latter is for blue yarn and should not turn blue too quickly (allow 60 seconds at least).

Rest the vats for 1 hour after 3 hours work. Never hurry the vats. It is a good thing to have hydrosulphite slightly in excess as this prevents premature oxidization; too much will strip off the indigo white already deposited on the yarn.

Caustic Soda must always be used with the greatest caution or the yarn will be tendered and ruined.

Finally, unless the yarn is completely scoured it is impossible to obtain a clear colour, or a blue which will not rub off.

The figures given are for Indigo bearing 100% Indigotine, therefore in using vegetable Indigo do not add _all_ the Caustic or Hydrosulphite, but depend on the gla.s.s test rather than on measurements.

_WOAD_

Woad is derived from a plant, _Isatis tinctoria_, growing in the North of France and in England. It was the only blue dye in the West before Indigo was introduced from India. Since then woad has been little used except as a fermenting agent for the Indigo vat. It dyes woollen cloth a greenish colour which changes to a deep blue in the air. It is said to be inferior in colour to indigo but the colour is much more permanent. The leaves when cut are reduced to a paste, kept in heaps for about fifteen days to ferment, and then are formed into b.a.l.l.s which are dried in the sun; these have a rather agreeable smell and are of a violet colour. These b.a.l.l.s are subjected to a further fermentation of nine weeks before being used by the dyer. When woad is now used it is always in combination with indigo, to improve the colour. Even by itself, however, it yields a good and very permanent blue.

It is not now known how the ancients prepared the blue dye, but it has been stated (Dr. Plowright) that woad leaves when covered with boiling water, weighted down for half-an-hour, the water then poured off treated with caustic potash and subsequently with hydrochloric acid, yield a good indigo blue. If the time of infusion be increased, greens and browns are obtained. It is supposed that woad was "vitrum" the dye with which Caesar said almost all the Britons stained their bodies. It is said to grow near Tewkesbury, also Banbury. It was cultivated till quite lately in Lincolnshire. There were four farms in 1896; one at Parson Drove, near Wisbech, two farms at Holbeach, and one near Boston. Indigo has quite superseded it in commerce.

LOGWOOD

(_Bois de Campeche, Campeachy Wood_)

Logwood is a dye wood from Central America, used for producing blues and purples on wool, black on cotton and wool, and black and violet on silk. It is called by old dyers one of the Lesser Dyes, because the colour was said to lose all its brightness when exposed to the air.

But with proper mordants and with careful dyeing this dye can produce fast and good colours. Queen Elizabeth's government issued an enactment entirely forbidding the use of logwood. The person so offending was liable to imprisonment and the pillory. The princ.i.p.al use for logwood is in making blacks. The logwood chips should be put in a bag and boiled for 20 minutes to 1/2 an hour, just before using.

RECIPES for DYEING with LOGWOOD

(1). BLACK

Mordant the wool for 1 to 1-1/2 hours with 3 per cent Chrome and 1 per cent Sulphuric Acid. Wash and dye in separate bath for 1 to 1-1/2 hours with 50 per cent Logwood. This gives a blue black.

A dead black is got by adding 5 per cent Fustic to the dye bath.

A green black by adding more fustic. Also by adding 3 to 4 per cent Alum to the mordanting bath a still greener shade can be obtained.

A violet black is produced by adding 2 per cent Stannous Chloride to the dye bath and continue boiling for 20 minutes.

(2). LAVENDER

Mordant with 3 per cent Bichromate of Potash for 45 minutes and wash.

Dye with 2 per cent madder, 1 per cent logwood. Enter the wool, raise to the boil and boil for 45 minutes. The proportion of logwood to madder can be so adjusted as to give various shades of claret to purple.

(3). A FAST LOGWOOD BLUE

(Highland recipe.) Mordant with 3 per cent Bichromate of Potash and boil wool in it for 1-1/2 hours. Wash and dry wool. Make a bath of 15 to 20 per cent logwood with about 3 per cent chalk added to it. Boil the wool for 1 hour, wash and dry. The wool can be greened by steeping it all night in a hot solution of heather till the desired tint is obtained.

(4). RAVEN GREY FOR WOOL

Mordant with 25 per cent Alum for 1/2 hour at boiling heat; then take it out, add to the same liquor 5 per cent copperas, and work it at boiling heat for 1/2 hour. Then wash. In another copper, boil 50 per cent logwood chips for 20 minutes. Put the wool into this for 1/2 hour; then return it into the alum and copperas for 10 to 15 minutes.

Wash well.

(5). DARK RED PURPLE WITH LOGWOOD

(2-1/2 lbs.) Mordant with 25 per cent alum and 1 per cent cream of tartar for 1 hour. Let cool in the mordant, then wring out and put away for 4 to 5 days.

Dye with 60 per cent logwood and 25 per cent madder. Boil up the logwood and madder in a separate bath and pour through a sieve into the dye bath. Enter the wool when warm and bring to the boil. Boil from 1/2 hour to 1-1/2 hours. Wash thoroughly in soft water.

(6) PURPLE

(For 1 lb.) Mordant wool with 1/4 lb. alum and 1/2 oz. tartar for one hour; wring out and put away in a bag for some days. Dye with 1/4 lb.

logwood for 1 hour.

FOOTNOTES:

[Footnote E: If the Extract is used alone, a mordant is not essential.]

CHAPTER VI

RED

KERMES COCHINEAL MADDER

_KERMES_

Kermes, or Kerms, from which is got the "Scarlet of Grain" of the old dyers, is one of the old insect dyes. It is considered by most dyers to be the first of the red dyes, being more permanent than cochineal and brighter than madder. In the 10th century it was in general use in Europe. The reds of the Gothic tapestries were dyed with it, and are very permanent, much more so than the reds of later tapestries, which were dyed with cochineal. Bancroft says "The Kermes red or scarlet, though less vivid, is more durable than that of cochineal. The fine blood-red seen at this time on old tapestries in different parts of Europe, unfaded, though many of them are two or three hundred years old, were all dyed from Kermes, with the aluminous basis, on woollen yarn."