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
---
(25) These are chiefly allum, lime, marine salt, nitre, sal-ammoniac, tartar, fixed and volatile alkalies, with various metallic salts, and are in general called astringents, though rather forced, as astringent is more applicable to medicine, and some, articles have astringent and colouring qualities united, as galls, sumach &c. but salts or acids would be too general terms; and technicals frequently want allowance in the use of them; thus, specifically speaking, lime is caustic; ash, alkaline; tartar, acid; allum, saline; &c. hence, though not a practical term in printing, wherever astringent is used it alludes to striking or fixing the colour.
(26) The manner of salts being applied in dyeing is different, according as the subject is wool, cotton, silk, velvet, thread, &c, their pores being different, in various respects, and consequently their aptitude to receive colour is so likewise: thus some substances, as cochineal and kermes, that in dyeing give a scarlet to wool (which is the easiest substance to colour) give a very dull one to silk and cotton, and require a larger quantity, see note 36 and 41. The remark is likewise applicable to the different manufacturing of goods; and it is mentioned in the beginning of Bleaching, that the preparation is necessarily different. This is intimated here to those whp think it is indifferent what any tingeing substance may be applied to, and may have occasion to print an other articles than cotton or linen.
(37) Roman allum being white, and pure, is the raast proper, as roch allum contains iron. — See Pomet on drugs and the compendium of chemistry.
(28) Iron, rather than causing a black, contributes to it from the effect of its attriction, as oak turns black by sawing; white grease is made black by its friction with iron; green fruit turns black if cut with a knife; the black colour in earthen ware is swing to vitrified iron; and copperas which is used in procuring a black, is the salt of pyrites, with which iron is incorporated.
The cause of rottenness, attributed generally to the copperas, used in procuring black, is ewing to the earth of iron (where it is used) not being separated from the solution, and when said to be rotten from copperas, it is from the gross particles not finding easy admission into the pores; hence they in a manner burst open their enclosures, tearing of course, the parts that resist. — See iron liquor further on.
(29) Here, according to the laws of affinities, (which should always be borne in mind in whatever relates to colour-making) it is said (though observed before, see article maddering) that between the as tringent introduced to six the colour, and the colouring substance itself, there must be a mutual attraction, or a greater one than between either of the substances and the liquid in which either may be suspended, else they cannot unite so as to form that cement which causes permanency; hence (as before observed) there are no black substances that any saline astringent will take hold of, and even from their natural dryness, their particles keep at too great distance in water, ever to attract each other sufficiently. — See note 31.
(30) Hellot and D'Apligny says there are many plants, which, treated like the anil (from which is procured indigo) would probably produce a black feculence, such as the liquorice root, choak weed, and several others, as mentioned further on in speaking of colouring substances; Dr. Lewis, how ever, doubts it.
The antient Gauls used myrtles in dyeing purple, and it is thought with the use of astringents a black might be raised with them, as well as from the barberry or prickly sorrel; though some who have tried have not succeeded: Linnæus says, St. Christopher's herb gives with allum a black, and Hellot says, a tree in the Brazils is of such a black tingeing quality, as to dye the flesh and bones of animals that eat it, black, similar to the red effect of madder: the anacardium nut is said to produce simply of itself a fast black: but in cases of this nature it is not much to be expected that persons will go out of an old track, and if inclined to it, sufficient quantities of such articles are not to be procured till cultivated for such purposes. — See note 42.
In general, infusions of astringent vegetables mixed with green vitriol, produce black; rain water catched in the open fields has a blueish cast, but what is catched from houses grows purple, from some alkaline quality it thus receives.2d, Of Articles that procure from various Substances their colouring Properties. (25)
The articles of this description are very numerous, and are the chief or only agents we are in possession of, in procuring permanency of colour, and the most general in its application is allum; its superior power is consest by its uniting two qualities, heightening colours, and fixing them at the lame time. (26)
Colours that are not permanent, are, it is apprehended, owing to she want of some such substances being previously applied to the cloth, or of not being able to unite with them; hence (as has been sad) the colouring particles not finding pores sufficiently open to imbibe them, are supposed to lay chiefly on the surface.
Lime has the property of uniting two of the greatest opposites in nature, Salts and Earths; it is soluble in water, by means of fire; but the air renders it indissoluble again; thus it is capable of forming an unalterable cement when united with other matters; but allum, as above-said, has a property beyond, which is that of attracting certain colouring particles (27): nitre, marine salt, sal ammoniac, sacrum saturni, and tartar, are, strictly speaking, only alterants, by changing the red to a crimson, a blossom, a pink, &c. Neutral salts with a metallic basis, rather give strength to the colour, than solidity in respect to its fixity, for every colouring substance will vary, its shade, according to the nature of the earth that attracts its particles:
Two neutrals, Copperas and Roman vitriol, with metallic bases, are in common use, oweing to their astringent quality being in union with their alterative principle.
In procuring a black, it is in general by in troducing within the pores of the cloth, particles of iron dissolved in various liquids, and precipitating them on the subject by means of some astringent substance supplied with phlogiston, sufficient to render the iron black; but this should be done so that the precipitating matter do no injury, and that can only be accomplished in proportion as the particles are dissolved. (28)
It is to be understood (as before said) there is no black substance, vegetable, animal, or mineral, that possesses the durable tingeing properties of indigo, madder or weld (these blue, red and yellow substances are mentioned, being most in use) for all black foeculencies are of too dry a nature to be introduced and fixed in any, either by any adhesive quality tof their own, or by the previous use of astringents, as they only act on unctuous substances. (29) Galls, sumach, logwood, &c. containing within them the primitive colours, blue, red, and yellow, it is thought a black reproduced from a combination of them, and according as either is acted on by the salt of copperas or iron, and as made use offer procuring a black, it indicates by the shade that is left when the black is flown, on which the salt was employed. (30)
Ei kommentteja :
Lähetä kommentti