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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(70) Prussian blue is iron, in combination with prussic acid, which acid has precipitated it from its solution. The acid is prepared by calcining animal matters (generally oxes blood) with alkali. The common solution of Prussian blue is by solution of tin or marine acid; something of which kind was lately hawked among London printers as a blue to print with, and called the true Switzerland blue. But the whole proved rather an abortion, — See further on, respecting metallic calces and precipitates.
(71) By the agency of lime, or by adding pure alkali to the woad, when fermented with water.
(72) Forming a liver of sulphur, which is the true solvent. — Livers or hepars being combinations. of sulphur, with alkalies and earths, and the orpiment here which is decomposed, in the course of the processes, contains sulphur.
The properties of indigo are such, that nature seems to have set a barrier to any attempt to use it like many other articles, when it is formed into the pencilling blue colour; (china blue colour being governed by other processes) so as only to require rincing, with all the ingenious contrivances of wired sieves, agitators &c. either in procuring fine lines, or evenness of colour, when the shapes are large and frequsnt (note 39) for as partly observed, note 37, till we can either displace or deaden the attractive powers of a component part of the atmosphere, or else chain down, as it were, the volatility of a principle in the indigo, we must despair of having it in subjection. The new doctrine, however, of gasses, is at present employed with strong, hopes of using it, at leas., to more advantage than hitherto.
* Vital air, which the indigo acquires during combustion, according to the new theory. — See Berthollet's memoirs.
(73) Which will unavoidably be the case if kept too much exposed to the air by attraction of the fixed air* (*Which is a weak acid.) from the atmosphere, chalk being lime saturated with fixed air, which when impelled by fire, or a stronger acid than the fixed air is, is extricated; but which the time afterwards, endeavours to regain. But this attraction if fixed is most manifest in lime water, and every one knows time gets moist soon in the air, especially if the air itself be moist.
** A blowing day is bad for drying the cloth, as it is apt to smudge; but when the blue is once fixed, it is not easily moved.
(74) A desideratum in china blue, printing exbiting it, with deep and pale shade along with madder colours, without pasting or otherwise pre setting it. It is however to be done by certain preservatives, though not by common paste; and even a strong blue to be formed by certain prepared vats, so as not to hurt the madder colours; and it is well known, the writer a few years ago drew patterns with two blues intermixed with chintz work (the house of Ashby and Philpot had the first) but it was deemed impracticable; he however hopes; thinks it will not long be deemed so.
(75) A composition of tobacco pipe clay, and soft soap.
(76) If vitriol of lime or magnesia be in water, the vitriol unites with the alkali, and the lime or magnesia with the oil, forming an almost insoluble soap, floating on the water having the appearance of a curd: hence here cannot be a perfect solution of the soap
*** A solution of soap being poured oh a metallic solution, its acid seizes the alkali of the soap.
Fat oils and bitumen make a fat varnish. By combining fat oils with calces of lead, adding a quantity of water and evaporating the liquor, a thick syrup is obtained which does not crystalize
(77) Being most deprived of its fixed air (see note 73) and consequently there can be little effervescence. The chief, and, perhaps, only proper agent in the production of this colour is indigo; as woad, prussian blue (70) logwood and some other substances, have hitherto not answered not answered the hopes of any. Woad however is the closest of kin to indigo; in fact, indigo is obtainable from it. (71)
The common solution of indigo, or opening of it, as usually termed, it has been said is with ash, lime, orpiment (72) and concentrated vitriolic acid: but, it is here further observed, that indigo, in order to be dissolved, must be decomposed, and a substance which it has acquired, which see below, be expelled. Woad, in which putrefaction has commenced, affects this, and at the same time gives a blue. The appearance that indigo exhibits (note 37) in solution, is its becoming green, or shewing a green surface with lime, alkali or certain calces: The colouring matter here evidently flies off, and until that lakes place it is insoluble. (*) The copperas and orpiment are supposed to do this from certain powers of affinity or attraction.
The best methods for forming blue vats, accordto the most respectable French chymists and dyers, are 1st, By macerating the indigo in a strong ley, then grinding it, adding lime and water to it, raking it when the lime is slacked, and then adding green copperas or orpiment. — After this, the indigo (previously ground) is to be added, raked and then suffered to rest as usual, and, method, being more simple, is by adding certain proportions of indigo, green copperas, lime and water, and this composition, after raking, is fit for dyeing in a few hours.
In these and all other processes in which lime and water are used, the lime must not be too chalky chalky (73) nor the copperas too calcined, and the lime should always exceed; or the solution of the indigo will be the more imperfect; neither neither should it be in use but a few days, as it then gets weak.
Immersing the cloth afterwards in diluted vitriolic acid heightens the colour; it is generally immersed twice, the first time being called roughing, but this commonly hurts madder colours, hence chiefly used with china blue colours only, and these when dull may be mended by further immersions.**
To make this blue, some make a solution of antimony first, and add indigo afterwards. A dry preparation in these processes as well as in others is to be procured from indigo.
The curious may sublime indigo, and thereby procure flowers as with zinc, sulphur, &c. For experiments in a small scaleit may see done in a common flask over a common fire, defending the flask from the contact of the fire.
To speak of the Saxon blue is hardly worth while, it is so very fugitive, being a mere solution (if it can be called such) of indigo in vitriolic acid. If this, however, be added to a proper solution of indigo, a green may be procured; and if the acid be rather predominant, it increases the intensity.
In blue dipping, if the cloth appear clean and white, as in other cases mentioned under the section of copperwork, the preparation is generally dispensed with, on a presumption the cloth has no oiliness in it; but this does not always seem to be the case, and the writer cannot think subordinate blue dippers, printers, and cylinder workers, are always in fault, when stormont and other close work appears uneven. And he knows, that faults are sewer where preparation is more indiscriminate. Even for common chemical work, it may be more needful than perhaps many think; for it is certain, that if the ashing be not properly or sufficiently performed the cloth will turn brown in time: and this, by the way, may account for the brownness that is observed to take place in cloth where chemical colours are brought up in lime: water, unless it be supposed that the lime may deposit some of its earth, or some substance that may be in union with it, (as lime itself is earth) which in time causes that brownness. In this case, how far an immersion in some acid may dislodge it the writer will not say, but the acetous acid seems, most proper: as to the vitriolic that must unavoidably form a selenite. (74.)
In making paste colour (75) in order to preserve certain shapes in white on a blue ground; waters impregnated with selenite or other earthy matters, are detrimental. (76) However, in any case where the soap is decomposed, the paste does not work freely. Instead of tallow to which it is requisite to keep a heat continually applied; some of the fat oils; butter of cocoa, &c. might probably be used to advantage. In wax printing the wax is necessarily kept fluid over burning charcoal.
Lemon-juice being made use of in some cases to procure similar effects, by discharging the colour, it is intimated here how to procure it.
Express the juice of lemons, of any fort, ripe or unripe; expose it to the sun till it deposits a sediment, filter it till the liquor is clear and set it in a sand bath; change the receiver when the drops are acid: The acid preserved in the receiver, is to be kept in vessels secured from the air; Or ,saturate the lemon-juice with lime, wash it and pour it on a due quantity of vitriolic acid; the liquor poured from the precipitate is tlie acid of lemons. — Lavoisier's Chymistry.
The best lime is that what effervesces the least with vinegar, (77) or which mixes quickly with water, and with the greatest heat.
To get the purest lime (though not so abso lutely needful in the above-mentioned processes) is by boiling powdered chalk repeatedly, dissolving it in radical vinegar, and precipitating it by concrete ammoniac. For pencilling blue, pure lime is, however, indispensably needful; in fact, in all the solutions of indigo where it is used, as is the lime so will be the colour.
Lime water when used to bring up the colour, whether bright green, buff, chemick blue, &c. produces the effect by decomposing the mixture applied to the cloth: the acid that held the articles in union being separated from it, and the remainder left on the cloth.
From the preceding suggestions it is inferred, that good black and purple colour is only to be procured from well saturated iron liquor: good red, and yellow from pure vinegar and earth of allum; and good blue by the solution of indigo with pure lime, ash, &c. but to enter here into a description of the tests and analyzation of these mixtures would be too complex and prolix, and for reasons given, it would be almost useless, for it comprizes an analysis of every article that is used both in its simple state and when combined with any other substance. It is, however, certain that no man can properly be deemed a colour maker unless he can do it, if only respecting the common application of them, saying nothing ot those accidents that often confound the best colour makers that we have.
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