The London Encyclopædia: Part II. The Practise of Dyeing. Of Dyeing Compound Colors.
The London Encyclopædia, or Universal Dictionary of Science, Art, Literature, And Practical Mechanics, Comprising A Popular View of The Present State of Knowledge.
By The Original Editor of The Encyclopædia Metropolitana, Assisted By Eminent Professional And Other Gentlemen.
In Twenty-Two Volumes
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Part II. The Practise of Dyeing. Of Dyeing Compound Colors.
235. On this branch of dyeing, M. Berthollet remarks, that simple colors form, by their mixture, compound color; and if the effects of the coloring particles did not vary, according to the combinations which they form, and the actions exercised on them by the different substances present in a dyeing bath, we might determine with precision the shade that ought to result from the mixture of two other colors, or of the ingredients which afford these colors separately: but the chemical action of the mordants, and of the liquor of the dye bath, often changes the results; theory, however, may always predict these effects to a certain degree.
It is not the color peculiar to the coloring matter which is to be considered as the constituent part of compound colors, but that which they must assume with a certain mordant, and in a certain dye bath. Hence, our attention ought to be principally fixed on the effects of the chemical agents employed.
It is in this department of dyeing that the intelligence of the operator may be most useful, by enabling him to vary his processes, and to arrive at the proposed end by the simplest, shortest, and least expensive way.
The processes for compound colors are very numerous. We shall mention only those which moset merit attention, and shall establish the principles on which they ought to be conducted by particular examples.
236. Of Dyeing Wool Green - Green is obtained by the mixture of yellow and blue; and it is distinguished into many different shades; but it requires experience to obtain this color uniform and without spots, especially in the light shades. It is possible to produce green by beginning either with the yellow or the blue dye; but the first method is attended with some inconvences; for the blue soils the linen, and a part of the yellow being dissolved in the vat, changes and makes it green; the second method is, therefore, preferable. It is common to employ the pastel vat, but for some kinds of green, solution of indigo in the sulphuric acid is used; and then the blue and yellow are either dyed separately, or all the ingredients are mixed together, to dye by a single operation.
237. Solutions of copper with yellow substances may also be employed. The blue ground must be proportioned to the green which is desired; thus, for the green like that of a drake's neck, a ground of deep royal blue is given; for parrot green, a ground of sky.blue; for verd naissant, a ground of white-blue is necessary. After the cloths have received the poorer ground, they are washed in the fulling-mill, and boiled as for common welding, but for the lightfaster shades the proportion of salts is diminished. Most commonly the cloths intended for the light shades are boiled first; and, when these are taken out tartar and alum are added.
238. The process of welding is [...] the same manner as for yellow: [...] quantity of weld is employed, except [...] lighter shades, which, on the contrary [...] still smaller proportion. For the most [...]cession of shades from the deepest to the [lightest?] is dyed at the same time, beginning with the deepest and proceeding to the lightedt; [...] each dip, which lasts half an hour, or [...]ters, water is added to the bath. Some [dyers?] give each parcel two dips, beginning the [...] time with the deep shades, and the second, [...] the light ones; in that casem each parcel [...] remain a shorter time in the bath: for the very [...] shades, care should be taken that the bath [...] not boil. A browning with logwood and [...] sulphate of iron is given to the very deep [...].
The green obtained by means of the [...] of indigo in sulphuric acid, is [denom...? ...] Saxon green, from its having been first [practised?] in Saxony. We shall here give the [process? di?]rectred by Fr. Bancroft for this color.
239. The most beautiful Saxon greens may be produced very cheaply and [expeditio...? by?] combining the lively yellow which results [...] quercitron bark, murio-sulphate of [...] alum, with the blue afforded by indigo [dissolved?] in sulphuric acid, as for dyeing the Saxon green.
To produce this combination most [advan?]tageously, the dyer, for a full-bodied [...] should put into the vessel after the rate of [...] eight pounds of powdered bark in a [...] every hundred pounds of cloth, with only [...] proportion of water as soon as it begins. [...]warin; and when it begins to boil, [...] add about sixpounds of murio-sulphate [...] with the usual precautions, and a few [...] after about four pounds of alum. These [...] boiled together five or six minutes, [...] should be added , so as to bring the [...] liquor down to what the hand is able [...]. Immediately after this, as much sulphate of [indi?]go is to be added, as will suffice to produce [the?] shade of green intended to be dyed, [...] to mix it thoroughly with teh first [...] stirring, &c.; and this being fone, the [...] being previously scoured and moistened [...] be expeditiously put into the liquor, and [...] very briskly through it for a quarter of [...] in order that the color may apply itself [...] to every part, which it will certainly [...] way with proper care. By these [...] full, even, and beautiful greens may be gener[...] dyed in half an hour; and, duing this [...] is best to keep the liwuor at rather less [...] boiling heat. Murio-sulphate of [...] prederable for this use tot he dyers' [...] because the latter consists chiefly of [...] which, by its highly injurious actions upon [...] would render that part of the green [...] fugitive. But no such effect can result from the murio-sulphate of tin, since the [...] has no action upon indigo; and the [...] that very acid which alone is proper to [...] it for this use.
Respecting the beauty of the color this produced, those who are acquainted with [...] equalled lustre and brightness of the [quercitron?] yellows, dyed with the tin basis, [...]
conclude, that the greens composed therewith, will prove greatly superior to any which can result from the dull moddy yellow of old fustic; and, in point of expense, it is certain that the bark, murio-sulphate of tin, and alum, necessary to dye [...] given quantity of cloth in this way, will cost less than the much greater quantity (six or eight times more) of fustic, with the alum necessary for dyeing it in the common way, the sulphate of indigo being the same in both cases. But in dyeing with the bark, the vessel is only to be filled and jeated once; and the cloth, without any previous preparation, may be completely dyed in half an hour; whilst in the common way of producing Saxon greens, the copper is to be twice filled; and to this must be joined the fuel and labor of an hour and a half's boiling and turning the cloth, in the course of preparation, besides nearly as much noiling in another vessel to extract the color of the fustic; and after all, the dyeing process remains to be performed, which will be equal in time and trouble to the whole of the process for producing a Saxon green with the bark; so that this color obtained from bark will not only prove superior in beauty, but in cheapness, to that dyed with old fustic.
240. Of Dyeing Silk Green. - In communicating to silk the green color, it requires very great caution to prevent the stuff from being spotted and striped. Silk intended for greens is boiled as for the ordinary color; for light shades, however, it should be boiled thoroughly as for blue.
Silk is not first dyed blue like cloth; but, after a strong aluming, it is washed slightly in the river, and distributed into small hanks, that it may take the dye equably; after which it is turned carefully round the sticks, through a bath of weld. When it is thought that the ground is sufficiently deep, a pattern is tried in the vat, to see if the color has the wished-for tone; if it has not ground enough, decoction of weld is added; and, when it is ascertained that the yellow has reached the proper degree, the silk is withdrawn from the bath, and passed through the vat as for blue.
To render the color deeper, and at the same time to vary its tone, there are added to the yellow bath, when the weld has been taken out, juice of Brazil-wood, decoction of fustet, and anotta. For the very light shades, such as apple-green and celadon-green, a much weaker ground is given than for the other colors. For the light shades, if not for sea-green, it is preferable to dye yellow in baths which have already been used, but in which there is no Brasilwood or fustet, because the silk, perfectly alumed, dyes too rapidly in fresh baths, and is thence subject to take an uneven color. Dr. Bancroft recommends the following process for producing Saxon green at one operation, as the most commodious and certain: -
241. A bath is prepared of four pounds of quercitron bark, three pounds of alum, and two pounds of murio-sulphate of tin, with a sufficient quantity of water. The bath is boiled ten or fifteen minutes, and when the liquor is in temperature till the hand can bear it, it is fit for dyeing. By adding different proportions of sulphate of indigo, various and beautiful shades of green may be obtained, and the color thus produces is both cheap and uniform. Care should be taken to keep the bath constantly stirred, to precent the coloring matter from subsiding. Those shades which are intended to incline most to the yellow, should be dyed first; and, by adding sulphate of indigo, the green, having a shade of blue, may be obtained.
242. To produce what is called an English green, and which is more beautiful than the ordinary greens, and more durable than Saxon green, Guhliche recommends the following process: - He gives the silk, first of all, a clear lue in the cold vat; he speeps it in hot water; washes it in runnin water; passes it through a weak solution of alum; prepares a bath with the sulphuric solution of indigo, a little of the solution of tin, and a tincture of Avignon berry, made with a vegetable acid. He keeps the silk in this bath till it has assumed the wished-for shade; he then washes and dries in the shade. The lighet hues may be dyed in the sequel. The shades may be varied with more or less blue, or more or less yellow, by the proportions of the indigo solution, and of the yellow substance. When it is wished to give a goslin-green to silk, a light blue is communicated to it, either in the hot vat or in the cold; it is passed through hot water, washed in running water, and while moist it is passed through a bath of anotta.
243. Of Dyeing Cotton and Linen Green. - To give a green color to linen and cotton yarns, it is proper to begin with scouring them well; then they must be dyed in the blue vat, cleaned in water, and passed through the weld process.
The strenght of the blue and the yellow is proportioned to the color that is wanted. As it is difficult to give uniformity to the cotton velvets in the ordinary blue vat, they are usually dyed yellow with turmeric, and the green in produced with solution of indigo in sulphuric acid.
244. To dye beautiful greens upon cotton, Chaptal recommends that it be first dyed of sky-blue color with indigo, dissolved by potassa and orpiment, then macerated in a strong solution of sumach, then dried and soaked in a solution of acetate of alumina, dried again, rinsed, and finally dyed with quercitron bark, in the proportion of twelve pounds to every fifty pounds of cotton. The quercitron is preferred to weld for this purpose, because the color of the former combines better with that of sumach.
245. M. D'Apligny recommends a method of dyeing cotton and linen of a fine sea or applegreen by means of a single bath; it is in substance as follows: - The liquor is prepared by mixing verdigris with a sufficient quantity of vinegar, and keeping the mixture in a bottle well stopped for fifteen days in the heat of a stove, and adding to it, about four hours before using it, a solution of potassa equal in weight to that of the verdigris, keepit it still hot. The cotton goods are first soaked in a warm solution, made by dissolving one ounce of alum in five quarts of water for every pound of cotton. The goods are again taken out, and, after adding the verdigris mixture, they are returned, and passed through the bath till sufficiently dyed.
Linen is dyed of the shades of olive and drake's neck green, by first giving it a blue ground, then galling and dipping it in a bath of acetate of iron; afterwards passing it through a bath of weld, combined with verdigris; and through another containing sulphate of copper, finally brightening the color by immersion in a solution of soap.
246. The green, says M. Berthollet, obtained by giving a yellow color to a stuff which has been previously dyed blue, and afterwards washed, presents nothing obscure. The color inclines more or less to yellow, or to blue, according to the tint of blue given, and the strength of the yellow bath. The intensity of the yellow is increased by alkalis, by sulphate of lime, by ammoniacal salts. It is diminished by acids, alum, and solution of tin. The shades vary likewise from the nature of the yellow substance employed.
These different effects will be obtained with the same ingredients in the formation of the Saxon green, according to the process adopted. If the Saxon blue be first dyed, tand the yellow color be nect given separately, the effects will be analogous to those just mentioned. But if solution of indigo be mixed with the yellow ingredients, the results are not the same, because the sulphuric acid acts in this case on the coloring particles, impairing the intensity of the yellow. If a succession of shades be dyed in a bath composed of yellow and the solution of indigo, the last approach more and more to yellow, because the particles of indigo become attached to the stuff in preference to the yellow ones, which therefore become predominant in the bath.