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.
1792Bleaching with sour milk or vegetable acid, not being in use now among Callico-Printers, the mineral is here chiefly spoken of; of which mode it may be observed, that it un questionably took some time to get into general practice, vitriol being of so corrosive a nature it might naturally be expected to injure the cloth very materially.
But experience has shewn, that by being praperly weakened, generally so much that it is not stronger than vinegar, and may even be drank, that consideration has therefore vanished. As for vegetable acids, formerly so much in use, that tart-loads of lemons, crab- apples, &c. were frequently brought into printing-grounds, all con tain a portion of oil that prevents the effect being gained so easily as by the vitriolic acid: The milk sours in vogue among bleachers, likewise gives way to the vitriolic; for with this acid no fermentation happens in its not tending to putresaction; but milk sours naturally tending to corruption, if through inattention it should happen while in contact with the cloth, it must damage it as well as undiluted vitriol; in fact, milk may be corrupted before it is used. Besides, milk fours take several days to perform its task, while vitriol souring is done in a space of time no way comparative; but above all, its effect in whitening is the great point in its favour, the absorbent particles in the cloth imbibing it so immediately, that the effect is very soon attained.
This operation, besides contributing to the whiteness of the cloth, is deemed generally needful for the purpose of clearing away stains occasioned by ink, iron, or other articles, Which water alone would have little effect on; it like wise forwards the whitening of the cloth, when laid down after printing.
REMARKS, &c.
(15) Except for the purpose of discharging colour when used in printing.
(16) Very various is the time, different coppermen, or theis employers will allow; it is to be done in a quarter of an hour, but very frequently a considerable time longer is allowed; but a point to be observed, and which ought to regulate it, is knowing when the acid has had its utmost effect, for keeping the cloth in beyond that time, every one must grant is unnecessary, and to a certain degree injurious. Similar to the above observation, it may be added, that the quantity of any article used in any of these processes, is as much undetermined; and even the necessity of some of the processes themselves, but that ever must be the case, while drugs, and the articles they are employed on, are of such different qualities, and the use of them governed by other circumstances of oeconomy, custom, prejudice, &c. hence it is more safe to speak in a general, than in a specisic or positive manner, and hence what is here said of the processes are called remarks, &c. rather than rules. Galling was formerly much used, but goods for printing being now of a softer texture, undapurer quality in general, it is nearly exploded.
(17) A Thermometer is certainly best for the purpose of ascertaining the warmth of the water, some mens' hands being so hard, that their sense of feeling in this instance can hardly be a criterion.
(18) In reipect to the modes of cleansing goods, it is amusing to think of the various ones that have been adopted by battledores, stocks, wash-wheels and and the like, most of which tend considerably to injure the cloth (this however is a circumstance very likely not much desired to be prevented by printers) but it does not appear absolutely certain the effect is so much produced by such violences as by the action of the water; hence the wash-wheel may be said to have the preference; the wash wheel, though, like other improvements of the day, has piobably had its turn; for much mis chief may happen if it be not attended: The dumb planker or wooden-man seems to have the preference. But after all, a plenty of water, with a good falling force, well directed, and the cloth kept in proper motion, would be better than anyof those violent methods, especially if some goods be suffered to remain a little time in a soft soap ley, (of no very considerable strength) and afterwards sufficiently rinced and thoroughly dried.
(19) The complaint against colours brought up in sumach, or bark, is that a good white is not procured no more than a good black (as spoken of before) and consequently that courseof, work is confined to close patterns. The Writer however has seen a slight fielding used with success, in light ground work.What article to use in this operation, whether mineral or vegetable acid, must depend a great deal upon discretion, or other circumstances; vegetable to be sure is now disused among printers in this process,(15) but still the modes in use are so various, that any particular one cannot be insisted on; those most usually adopted are by the vitriolic and marine acids; the proportions most generally about 2 gallons of vitriol to a kettle or upwards of 100 gallons of water, and this quantity is enough for 8 pieces of 28 yard 4-4th wide, or the same number of pieces of 21 yards 5-4th wide; but this depends on the strength of the spirit, and even on the goodness of the water; likewise the quality of the goods must be considered, chiefly in respect to the strength of the warp, and these circumstances are to regulate the time necessary for the process (16); The heat of the water is also of considerable import, for if too hot it takes away from the acid its proper energy, as it is the acid only that is supposed to operate in this case, the water being used only for the purpose of weakening it. By the water being rendered warm the vitriolic particles must the readier enter the pores of the cloth, the pores being by the action of the warm water rendered more open. (17)
If the souring be repeated, the acid should be diminished, from the texture of the cloth being opened by each preceding process; so that the oily particles which blunted the acids are nearly removed, and the alkaline and absorbent earths occasioned by the ashing, if alhing were used, are easily washed out.
The goods then generally are cleansed in a flack lined with lead, and if they are not foul, the liquor may be used again in the kettle.
After these operations, they must be well cleansed by winching and planking, or some other similar process, then run them between the squee zers, and as usual hang them on the stakes, or in the drying - house, previous to being calendered. (18)
For goods that are to be printed in chemical colours, or that are to be brought up in sumach, or american bark, no preparation is necessary, un less the cloth is evidently too foul to pass with out. (19)
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