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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(61) Thus it is common for the colour at the bottom of the tub to be unfit for use. See something similar in Exp. 6 in note 40.
(62) Chalk is lime saturated with fixed air, or aerial acid. Lime is chalk deprived of it.
In this case the stronger acid, that is, the vinegar, expels the weaker, that is, the fixed air, and takes its place, according to the 5th rule of affinities in tho compendium.
(63) If waters were carefully analyzed before being used, some would be found fit for black, though unfit for red, and so of other colours; is truths few are aware of the consequences of an indiscriminate use of hard or soft water; in short, it will render the proportions or articles necessary at one ground, perhaps useless at another. — see article preceding ashing and note 37 to maddering.
(64) The reader is again reminded colour here is a very improper term.
(65) Their attractions to the principal substance or basis of the colour is so be know by studying the laws of affinities.
(66) Some colourmakers nevertheless affect to be wonderfully secret in use of some of these. The writer knows of a great sum being given not far from London, for a recipe for red, because calx of tin was an ingredient. — see notes 35 and 79.
(67) The usefulness of dung, as an animal subfiance, helps the colouring process in callico printing See dunging.Allum, (that is, vitriolic acid and clay,) being mixed in solution with sugar of lead, (which is composed of vinegar and calx of lead,) a decomposition Or change of union takes place according to the laws of affinity; the vinegar leaving the calx of lead to join with the clay, or more properly the earth of allum; while the vitriolic add leaves the earth of allum to unite with the calx, forming with it an insoluble and useless mixture (61) consequently what remains, as useful, is the vinegar in union with the earth of allum (according to vulgar observation and language, sugar of lead-prevents the settling which would otherwise take place too suddenly) but in this mixture there being more acid than necessary, expressed in chymistry by the terms either of excess of acid, or a supersaturation of acid, chalk being added, takes hold of it: the chalk at the same time undergoing a decomposition (by the vinegar expelling the fixed air) (62) the effervescence which commences, evincing this operation.
Whether the necessity of this additament was discovered a priori, or by chance, or experiment, is no matter; it is certain that without it the colour is not so deep. For according to the common mode of proportions, without the use of chalk, there is a useless substance remaining, increasing the bulk ot the liquor without adding to its efficacy. (note 61) An alkali being added tends likewise to take up the excess of acid, hence some use ash in the red colour. (63)
The result, however, being now vinegar and the earth of allum, necessarily diluted; when it goes into the madder copper, the union between the, colouring matter of the madder, and the earth of allum (which forms what is often spoken of in this work as a cement) is easier affected than if with only a mere solution of allum. - Here be it observed, a second decomposition takes place, that is, of the vinegar and earth of allum, by the interposition of the third substance, namely, the colouring matter of the madder or weld, as either is used.
The vinegar is likewise found to agree better with the thickening than a mere solution of allum will, it being in tearers language, not so vittry, lumpy or fpecky; perhaps from not being so crystalizable.
In making red colour (64) various other articles, such as ammoniac, corrosive sublimate, tartar, calx of tin; arsenic, zinc, &c. are or have been occasionally added. When arsenic is used, there certainly should be ash added: Respectable colour-makers are however very sparing in the use of these articles (note 39.)
It is unnecessary (and in fact for reasons just added, not intended) to enter into a detail of their immediate effects, or the causes of them; their chief effects as said already, being as alteratives, (65) but they are necessarily spoken of here again.
It is, however, just intimated that tartar in its union with allum, does not act like sugar of lead: there is not a mutual decomposition, though they attract each other; the attraction is neverthe less destroyed in the copper, and a decomposition then ensues of the previous mixture, followed by a union of the colouring matter with part of it.
Calx of tin, ammoniac, &c. in their effects of brightening (as usually called) are efficacious in consequence of preventing that close attraction of the madder, weld, &c. to the allum, &c. — Tartar used for yellow has this brightening effect in a particular degree; it likewise brightens chymical colours, such as solution of cochneal, brazil, &c. and in printing kerseymeres and other animal subjects this falt is very useful. Urine in some cases strengthens the colour; corrosive sublimate tends to deepen it, but like as with tartar, ash should be used with it. Common experience will shew the effect of other substances, though now few of them are used in callico printing, as just observed. (66)
It is not to a vegetable substance that the at traction of the earth of alum is confined, it acts readily on animal substances, as in the instance of lakes (see note 33) here the alkali seizing the substance suspended in the solvent till then, is thrown down. In printing on woollen this circumstance is very manifest: hence it may here be said, that as in dyeing, a solution of isinglass, or of glue, added to the decoction of the vegetable substance, helps the effects by its attraction to calces, which otherwise would not be at tracted by the colouring substances. (67) — (See calces further on.)
In want of sugar of lead, it may easily be procured by dissolving any of its calces, cerusse excepted, in vinegar.
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