A Treatise on Calico Printing, VOL. I-II
Printed for C. O'Brien, Bookseller, Islington, and fold by Bew, Paternoster-row: Richardson, Royal Exchange: Murray, Fleet-Street: And the Booksellers of Manchester, Glasgow, Dublin, &c.
1792
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(24) It is thought the volatile alkaline particles of the dung, prevents the particles of the colouring drug from too copiously entering into the ground, (which is what is supposed to be meant by guarding the colour) and that of course they will chiefly be imbibed where necessary.The use of this operation is said to hinder the white part of the cloth, or that part wherever it may be, which is to appear white, being stained by the superfluous colour, or according to the usual phrase of coppermen, it is to guard the colour, and prevent marking off: this however will not be the case if too many pieces, particularly if the work is heavy, be entered in the same copper, and which may very easily be accounted for, as it is possible the copper may contain, after some pieces are entered, besides the dung, a solution of mineral and other salts, from the quality of the tbickning or sightning, or other superfluous mat ter that may be dissolved or disunited in the copper; and which may mix wish the acting power «f the dung, and cause stains. In this operation, by letting fresh water into the copper, the encrease of the liquid will cause the foul stuff to run over.
Something likewise may be observed, respecting the dung itself, according as it is gathered in, whether as taken up in afresh state, or when dry, or having remained a long while on the ground; or whether in an almost liquid state by rain or urine; as these circumstances must more or less affect it in the quality; for, be the effective principle what it may, it certainly must vary according to the different states in which it may be gathered: but whatever may be the case in that respect, care must be taken that the copper be not made too hot (as before said) especially if the dung be sresh and pure (if the word may be al lowed) its effective quality being then of the greatest power, and, if the paste or sightning be not entirely got rid of, the action of the dung will disturb the colour, and prevent the madder from striking as it ought.
As to the operation itself, after having filled your copper, proportion the durig to the work, in general, about 3 jets to 2 pieces, giving them about 40 ends in the copper, as quick as possible; the water that you impregnate with the dung must onjy be sufficiently heated, in order gradually to loosen the colour; and as it much depends on the superfluous matter being easy to be removed or not (as just observed) it must of course be carefully attended, and the proportions must be varied accordingly. After this operation, the goods must be winched and well planked, or otherwise cleansed; they are then according to the quality of them, to be sumached, and then snitchelled off, and washed.
In sumaching, proportion the drug to the course of the work, for which, as is often said, certain circumstances prevent giving precise rules, (25) sometimes indeed sumach is not necessary, and sometimes in common work it may be used with the madder, as it is supposed to assist it.
(25) So here it may be said, though weights and measures may be deemed standards, yet coppers, pails, &c. cannot, as being of no regulated sizes; and to say a little or a great deal, a proper quantity and the like, are but comparative terms, and consequently indefinite. — See note 3.
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