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
---
(13) Called bucking or boiling among profesled Bleachers, and by them the cloth is, or was, laid down and watered: But with Callico Printers they are generally laid almost loosely on the grass. Tho' as observed (notes 12 and 21 to General Reflections, and elsewhere) new modes will perhaps supersede the present; great address however will be required to introduce them in England into general practice, and certainty of effect.
* See Dr. Percival's Essays and 2nd Volume of Phil. Trans. of Manchester Society.
(14) It once happened that so trifling a circumstance as the ikinning of a dog spoilt several pieces, they having been laid, after souring, on the place where he was skinned.Of Ashing. (13)
Of this operation it may be said, and in which consist the esientials of Bleaching, that it removes some substance which is the cause of cloth appearing brown; and as the whole de pends on knowing its nature, in order to apply what will combine with it, and separate it from the threads, with the least injury, Dr. Home* made various experiments, the result of which was, that, after evaporation, an oily dark coloured substance was left, of an inflammable nature; and, on further experiments, it appears to be compounded of a viscid oil, and the earthy particles of the flax.
It is thought by some,that bleaching with lime may be rendered advantageous; lime having more power in whitening than vitriol has, but (as just said) at the same time it is more dangerous if used alone; but with about one part mixed with four of ash, its caustic quality may not be so effective.
It is a remarkable circumstance that some articles manufactured in India, and brought over unbleached, cannot be made white here. Another circumstance is, that May Dew quickly whitens cloth, and of this it has been observed, that im mense numbers of insects are formed in the sub stance left after evaporation, and these undergo very rapid changes; but how far, or in what manner such circumstances affect the cloth, remains to be determined.
REMARKS, &c.
There is no need for this operation when goods are sufficiently clear and white, and ashing pieces that are so, can only be of service to take out grease or any thing similar to it; but when they are uniformly brown, or brown threads are here and there visible, they certainly mould undergo the process; therefore, in this case, give them a few ends in the ash liquor, and attend the operation with great care, that it be effectually performed; for if it be not, it cannot be done by souring, much less by winching or planking; and if they are suffered to go to the madder copper without having undergone this process sufficiently, or if any greasy or oily quality remain in them, (14) or if there be any part brown, the maddering cannot have its due effect; for, as that brownness is a particular substance in the cloth, that from its nature must prevent the striking of the colour, no one need be told that the maddering must be imperfect, if it be not removed.
Take care that the water be not suffered to boil, before the ash is put in, and in that state it should be continued some time, and the ash should not be put in till near the beginning of the boiling, let it then boil for about ten minutes or more, observing to stir the ashes frequently from the bottom.
The strength of the ley, and the gradation of heat must be well attended, that the texture of the cloth be not too violently acted on by the ash; and the more effectually to imbibe it, it should be opened by degrees; for similar to common wash erwomen observing in putting linen, especially body linen, into boiling-water, that it fixes the dirt; or, (what is to be sure more remote) in culinary processes, in ordertoboil vegetables green, not putting them into the water till it boils, so here it may be said, the oily quality in the cloth would be in a manner closed up, within it, by the cloth being immersed in boiling water.
It is however necessary to be careful that the cloth is thoroughly dry before it is put in the liquor, otherwise the ley will not enter so readily into the body of it; for if it be wet the action of the salts will not be so powersul on the internal structure, nor answer the purpose of dislodging the filth by the aid of the water; but, on the contrary, will act more on the surface, and probably do the cloth some injury.
With coarse cloths there may not be such danger, through the water boiling before they are immersed in it, as with fine ones, from theopennels of the texture; but the precaution before given, is absolutely necessary to attend where the texture of the cloth is fine or slimsy.
After this operation, the goods must be perfectly cleansed from the ash, by soaking them in a cradle, and winching them in a running stream, clear and free from any mineral impregnation; then take them to the planks, or something similar, till deemed sufficiently cleansed; next lay them down to whiten, and after being taken up, rince them, and get them ready for the sour kettle.
Ei kommentteja :
Lähetä kommentti