The Dyer's Guide. Chapter IV. On Scouring and Dyeing Wool. Another process for black without a blue ground.

The Dyer's Guide
Being a Compendium of the Art of Dyeing
Linen, Cotton, Silk, Wool, Muslin, Dresses, Furniture, &c. &c.

With The Method of
Scouring Wool, Bleaching Cotton, &c.
Directions for Ungumming Silk, And For Whitening And Sulphuring Silk And Wool.
And Also
An Inttroductory Epitome of The Leading Facts in Chemistry, As Connected With The Art of Dyeing.

By Thomas Packer,
Dyer and Practical Chemist.

"Cet arte est un des plus utiles et des plus merveilleux qu'on connoisse."
- Chaptal.

"There is no art which depends so much on chemistry as dyeing."
- Garnett.

Second Edition,
Corrected and Materially Improved.

Printed for Sherwood, Gilbert, And Piper,

To dye one hundred weight of cloth, take thirty pounds of chipped logwood, half a bushel of alder-bark, and six pounds of sumach, and boil them together in a proper quantity of water for half an hour; then cool the decoction down with cold water, enter the cloth, turning it on the winch; bring it to a boil, having the sumach in a bag; boil and keep the cloth turning for one hour and a half: this is the ground. Have now ready fourteen pounds of sulphate of iron dissolved in water, which is to be laded into the copper by one man, while another turns the cloth for an hour at a boiling heat; it is then to be taken out, cooled, and aired, returned to the copper, and boiled gently for two hours, and then cooled again.

"While the cloth is cooling, six pounds of logwood, ten pounds of alder-bark, two pounds of argol, ten of soda, or common pot-ashes, and three pounds of sulphate of iron, are to be added to the liquor in the copper, and boiled one hour, when the goods must be turned and worked one hour; and, lastly, taken out and aired. This black is said to be of the hue of a raven's feather. This process is from Heigh.

The argol is professed to be put in to counteract the sulphuric acid of the sulphate of iron; the alkali is said to cause the logwood to retain its natural violet colour: and if too great a quantity of logwood be not used, the result would be as above stated. But the author presumes that such a black would not be at this time much esteemed. We object to the introduction of so much, indeed of any alkali or argol, as the time employed in performing the process is wasted. Alkali is good, however, where a chemic green is to be dyed black.

Wool will take up whatever the copper contains necessary to dye black; but, for the beauty of the colour and the durability of the cloth, it is best to let it have most of its ground of vegetable colour before it has the sulphate of iron, which blackens that ground, with sumach instead of galls; and even in some instances, dyeing some goods without the sumach.

Were the author, however, to direct the dyeing of black cloth, such as should be of the best kind, he would have an indigo ground with logwood and alder-bark, without old fustic or oak saw-dust; and to finish the cloth he would use sumach, sulphate of iron, and a small quantity of verdigris. He would give it the blue ground first; then the logwood, alder-bark, and verdigris; and then finish it with sumach and sulphate of iron.

If the blue ground were omitted, he should dye the cloth twice, giving it more of logwood and alder-bark, but verdigris the same; and finish it with sumach and sulphate of iron. Nevertheless, when we dye to a pattern, the pattern must be our guide.

Different goods will require different quantities of drugs. Logwood should be about one-fourth of the weight of the goods; the sulphate of iron about one-fifth of the logwood; alder-bark, when used, about the same quantity as sulphate of iron; but for some yarns this bark is not used, nor is it necessary; and where fustic or oak saw-dust is used, there is the less necessity for using alder-bark. The sumach must be about the same quantity as sulphate of iron. Remember that carbon is generally considered as that which makes the richness of a dye. That it is the iron in the sulphate of iron, combined with the tannin and gallic acid which are assumed to be in the sumach and logwood, that produces the blackness of the dye; but this theory is questionable. See below.

The way to ascertain when the quantities of drugs are most appropriate for producing the desired effect is as follows: -

First, ground with different quantities of drugs, from three to five or seven patterns, and use from one third to one fifth of sulphate of iron and sumach to the grounding; afterwards finish with the remainder of the sulphate of iron and sumach: the fuller the ground the richer will be the black, if the logwood be not in excess, and the quantities be used as thus stated.

We ought also to state here (from Berthollet, Vol. ii. p. 4.) that commonly more simple processes than any of those above described are employed for black. Thus the blue cloth is simply turned through a bath of gall-nuts, when it is boiled for two hours. It is next passed through a bath of logwood and sulphate of iron for two hours without boiling, after which it is washed and fulled.

A black may also be dyed without a blue ground with walnut rinds or the roots of the walnut tree; in this case the cloth receives a dun ground from the walnut husks or roots, and is afterwards made black in the manner above described, with logwood and sulphate of iron.

The blacks, however, without the blue ground are only given in general to inferior cloths.

The colouring principle of logwood is called hematin; it is crystalline, of a rosy-white, and, viewed through a lens, very brilliant; its taste is slightly astringent, bitter and acrid; exposed to the action of fire in a retort it affords all the products of animal substances, and also a small quantity of ammonia, which proves that it contains nitrogen. It dissolves easily in boiling water; on adding some acid very gradually, it changes to yellow and then red. Potash and ammonia give the solution of hematin a purple red; if a great excess of these alkalies be added, the colour becomes violet-blue, then brown-red, and finally yellow-brown. In this state it is decomposed and cannot be recovered by any acids. Protoxide of lead, protoxide of tin, hydrate of tritoxide of iron, hydrate of copper, oxide of zinc and its hydrate, flowers of antimony and oxide of bismuth combine with hematin and give it a blue colour, with the loss of the violet shade. See notes to Ures Berthollet, Vol. ii. p. 420. See the explanation oi protoxide, &c. under oxide in Chapter I.

The above facts concerning logwood may, by the ingenious dyer, be applied on many occasions with great success.

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