Any of the treatments preparatory to, and following the actual dyeing of, any of these processes may be repeated if deemed necessary. The text-books on dyeing and the technical journals devoted to the subject frequently contain accounts of methods of dyeing Turkey red, but when these come to be dissected the methods are but little more than variants of those which have just been given.
Seeing that the theory or theories involved in this rather complex process of dyeing Turkey red, and that colourists are not agreed as to the real part played by the oil, the sumac and the clearing operations in the formation of a Turkey red on cotton, nothing will be said here as to the theory of Turkey-red dyeing.
Alizarine Red.—It is possible to dye a red with alizarine on cotton which, while being a good colour, is not quite so fast to washing, etc., as a Turkey red. This is done by using fewer treatments, as shown in the following process:—
Process 1.—Boil the cotton in soda.
Process 2.—Oil with Turkey-red oil, as in the Turkey-red process No. 2 above.
Process 3.—Mordant with alum or acetate of alumina.
Process 4.—Dye with alizarine as before.
Process 5.—Soap.
There are three distinct colouring matters which are sold commercially under the name of "alizarine". These are: alizarine itself, which produces a bluish shade of red; anthra-purpurine, which gives a similar but less blue red than alizarine; and flavo-purpurine, which produces the yellowest reds. The makers send out all these various products under various marks.
For dyeing Turkey reds the flavo-and anthra-purpurine brands or yellow alizarines are to be preferred; for pinks and rose shades the alizarine or blue shade brands are best.
Alizarine Pink.—This can be dyed in the same way as Turkey red, only using for full pinks 4 per cent, of alizarine in the dye-bath, or for pale pinks 1 to 2 per cent. It is advisable to reduce the strength of the oiling and mordanting baths down to one-half.
Alizarine Violet.—Alizarine has the property of combining with iron to form a dark violet colour, and advantage is taken of this fact to dye what are called in the dyeing and calico printing trades alizarine purples and lilacs, although these do not resemble in hue or brilliance the purples and lilacs which can be got from the direct dyes. They have not the importance which they formerly possessed, and but a mere outline of two processes for their production will be given.
Alizarine Purple.—Process 1. (1) Boil with soda, (2) prepare with Turkey red oil, (3) mordant by steeping in copperas liquor at 4° Tw. for twenty minutes, take out, allow to lie on stillages overnight, then wash and dry. For deep purples it may be advisable to repeat these treatments; for pale lilacs using them at half strength is advisable. (4) Dye with 8 to 10 per cent. of alizarine blue shade, working as described under Turkey red. The best results are obtained when 1 per cent, of chalk is added to the dye-bath. (5) Soap as in red dyeing.
Process 2. (1) Boil with soda, (2) oil with Turkey-red oil, (3) steep in pyrolignite of iron (iron liquor) for one hour, then age by hanging in the air. (4) Dye as before. (5) Soap.
Fine blacks are got if after oiling the cotton is treated with sumac or tannic acid, then mordanted with iron and dyed with alizarine as usual.
Chocolate Browns.—Fine fast chocolate browns can be got from alizarine by using a mixed mordant of iron and alumina, either the acetate or the sulphate. By varying the relative proportions various shades can be obtained.
Alizarine Orange—Prepare the cotton as if for dyeing a Turkey red, but use in the dye-bath 8 to 10 per cent. of Alizarine orange.
Alizarine Blue—The cotton is boiled three hours with 3 per cent. ammonia soda at 30 lb. pressure, and then washed thoroughly. The boiled, washed and hydro-extracted yarn is oiled with a solution containing from ¼ lb. to 1½ lb. Turkey-red oil, 50 per cent. for every gallon of water. It is then wrung out evenly and dried for twelve hours at 150° F.
Tannin Grounding.
The oiled and dried cotton is worked three-quarters of an hour in a vat containing a tannin solution (1 oz. per gallon). The cotton remains in this liquid, which is allowed to cool off for twelve hours, then it is hydro-extracted. Sumac turns the shade somewhat greener, which is noticed especially after bleaching, therefore tannin is given the preference.
Chromium Mordant.
The cotton treated with tannin and then hydro-extracted is worked cold for one hour in a vat containing a solution of chromium chloride at 32° Tw., and remains in this solution twelve hours. The cotton is then hydro-extracted and washed directly; it is best to employ running water. A special fixation does not take place. The cotton is now ready for dyeing. The solution of chromium chloride and the tannin solution can be used continuously, adding fresh liquor to keep the baths up to strength.
Dyeing—For dyeing, water free from lime must be used. Water having not more than 2.5° hardness can be employed if it is corrected with acetic acid, thereby converting the carbonate of lime into acetate of lime. Very calcareous water must be freed from lime before use. The dye-bath contains for 100 lb. cotton 15 lb. Alizarine blue paste (A R or F, according to the shade desired), 35 lb. acetic acid (12° Tw.), 15½ lb. ammonia (25 per cent.), 2¼ oz. tannin. The cotton is worked a quarter of an hour in the cold; the temperature is raised slowly to a boil, taking about one hour, and the cotton is worked three-quarters of an hour at that heat. Finally the cotton is washed and hydro-extracted. The dyed and washed cotton is steamed two hours at 15 lb. to 22 lb. pressure. Steaming turns the shade greener and darker, and increases the fastness. After steaming the cotton it is soaped one or two hours at the boil, with or without pressure. According to the quality of water employed, 2 to 5 parts soap per 1,000 parts water are taken.
Brown.—A fine brown is got by a similar process to this, if instead of Alizarine blue, Alizarine orange is used in the dye-bath. A deeper brown still if Anthracene brown, or a mixture of Anthracene brown and Alizarine blue, be used.
Claret Red.—Clarets to maroon shade of red are got by preparing the cotton as for blue given above, then dyeing with alizarine.
Logwood Black.—One of the most important colours that come under this section is logwood black, the formation of which on the fibre depends upon the fact that the colouring principle of logwood forms a black colour lake with iron and also one with chromium.
There are many ways of dyeing logwood blacks on cotton, whether that be in form of hanks of yarns, warps or pieces. While these blacks may be, and in the case of hanks are, dyed by what may be termed an intermittent process, yet for warps and piece goods a continuous process is preferred by dyers. Examples of both methods will be given. As in the dyeing of Turkey reds it is probable that no two dyers of logwood blacks quite agree in the details of their process, there may be variations in the order of the various baths and in their relative strengths. Typical methods will be noted here.
Dyeing Logwood Black on Yarn in Hanks.—Operation 1. Sumacing: Prepare a bath with 10 lb. sumac extract in hot water. Work the yarn in this for half an hour, then allow to steep for six hours or overnight, lift and wring. The liquor which is left may be used again for another lot of yarn by adding 5 lb. sumac extract for each successive lot of yarn. In place of using sumac the cheaper myrabolam extract may be used.
Operation 2. Ironing or Saddening: Prepare a bath with 3½ gallons nitrate of iron, 80° Tw. Work the yarn in this for fifteen minutes, then wring out. The bath may be used again when 1 gallon of nitrate of iron is added for each lot of yarn worked in it. In place of the nitrate of iron, the pyrolignite of iron or iron liquor may be used.
Operation 3. Liming: Work for ten minutes in a weak bath of milk of lime.
Operation 4. Dyeing: This is done in a bath made from 10 lb. logwood extract and 1 lb. fustic extract. The yarn is entered into the cold or tepid bath, the heat slowly raised to about 150° F, then kept at this heat until a good black is got, when the yarn is taken out, rinsed and wrung. The addition of the fustic extract enables a much deeper and jetter shade of black to be dyed.
Operation 5. Saddening: To obtain a fuller black the dyed cotton is sent through a bath of 1½ lb. of copperas, then washed well.
Operation 6. Soaping: Work for twenty minutes in a bath of 2 lb. soap at 140° to 150° F. Then wash well.
Much the same process may be followed for dyeing logwood black on warps and piece goods, jiggers being used for each operation.
Another method is to first work the cotton in pyrolignite (iron liquor) at 10° Tw., until it is thoroughly impregnated, then to dry and hang in the air for some hours, next to pass through lime water to fix the iron, and then to dye as before.
Continuous Process.—In this case a continuous dyeing machine is provided, fitted with five to six compartments. The cotton is first of all prepared by steeping in a bath of 12 lb. myrabolam extract for several hours, then it is taken to the continuous machine and run in succession through nitrate of iron liquor, lime water, logwood and fustic, iron liquor and water. The nitrate of iron bath contains 2 gallons of the nitrate to 10 gallons of water, and as the pieces go through fresh additions of this liquor are made from time to time to keep up the volume and strength of the liquor to the original points.
The logwood bath is made from 10 lb. logwood extract and 1 lb. fustic extract, and it is used at about 160° F. The quantities here given will serve for 100 lb. of cotton, and it is well to add them dissolved up in hot water in small quantities from time to time as the cotton goes through the bath.
The iron liquor given after the dyeing contains 2 lb. of copperas in 10 gallons of water.
Between the various compartments of the machine is fitted squeezing rollers to press out any surplus liquor, which is run back into the compartment. The rate of running the warp or pieces through should not be too rapid, and the dyer must adapt the rate to the speed with which the cloth dyes up in the dye-bath.
The addition of a little red liquor (alumina acetate) to the iron bath is sometimes made, this is advantageous, as it results in the production of a finer black. Iron by itself tends to give a rusty-looking, or brownish black, but the violet, or lilac shade that alumina gives with logwood, tones the black and makes it look more pleasant.
Some dyers add a small quantity, 1 per cent., of the weight of the cotton of sulphate of copper to the iron bath, others add even more than this. Some use nitrate of copper; the copper giving a greenish shade of black with logwood, and this tones down the iron black and makes it more bloomy in appearance.
Single bath methods of dyeing logwood blacks are in use, such methods are not economical as a large quantity, both of dye-wood and mordants, remain in the bath unused. Although full intense blacks can be dyed with them, the black is rather loosely fixed and tends to rub off. This is because as both the dye-stuff and the mordant are in the same bath together they tend to enter into combination and form a colour lake that precipitates out in the dye-bath, causing the loss of material alluded to above, while some of it gets mechanically fixed on the cotton, in a more or less loose form, and this looseness causes the colour to rub off.
For a chrome-logwood black, a dye-bath is made with 3 lb. bichromate of potash, 100 gallons logwood decoction at 3° Tw., and 6½ lb. hydrochloric acid. Enter the cotton into the cold bath, raise slowly to the boil and work until the cotton has acquired a full black blue colour, then take it out and rinse in a hot lime water when a blue black will be got.
A copper-logwood black is got by taking 100 gallons logwood decoction at 3° Tw., and 6 lb. copper acetate (verdigris); the cotton is entered cold and brought up to the boil. Copper nitrate may be used in the place of the copper acetate, when it is a good plan to add a little soda to the bath. Some dyers in working a copper-logwood black make the dye-bath from 100 gallons logwood liquor at 2° Tw., 4 lb. copper sulphate (bluestone) and 4 lb. soda. This bath is used at about 180° to 190° F., for three-quarters of an hour, then the cotton is lifted out, wrung and aged or as it is sometimes called "smothered" for five hours. The operations are repeated two or three times to develop a full black.
Logwood black dyeing has lost much of its importance of late years owing to the introduction of the many direct blacks, which are much easier of application and leave the cotton with a fuller and softer feel.
Logwood Greys.—These are much dyed on cotton and are nothing more than weak logwood blacks, and may be dyed by the same processes only using baths of about one-tenth the strength.
By a one-bath process 5 lb. of logwood are made into a decoction and to this 1 lb. of copperas (ferrous sulphate) is added and the cotton is dyed at about 150° F. in this bath. By adding to the dye-bath small quantities of other dye-woods, fustic, peach wood, sumach, etc., greys of various shades are obtained. Some recipes bearing on this point are given in this section.
Logwood is not only used for dyeing blacks and greys as the principal colouring matter, but is also used as a shading colour along with cutch, fustic, quercitron, etc., in dyeing olives, browns, etc., and among the recipes given in this section examples of its use in this direction will be found.
The dye-woods—fustic, Brazil wood, bar wood, Lima wood, cam wood, cutch, peach wood, quercitron bark, Persian berries—have since the introduction of the direct dyes lost much of their importance and are now little used. Cutch is used in the dyeing of browns and several recipes have already been given. Their production consists essentially in treating the cotton in a bath of cutch, either alone or for the purpose of shading with other dye-woods when the cotton takes up the tannin and colouring matter of the cutch, etc. The colour is then developed by treatment with bichromate of potash, either with or without the addition of an iron salt to darken the shade of brown.
The usual methods of applying all the other dye-woods, to obtain scarlets to reds with Brazil wood, Lima wood, peach wood; or yellows with fustic, quercitron or Persian berries, is to first prepare the cotton with sumac, then mordant with alumina acetate or tin crystals (the latter gives the brightest shades), then dye in a decoction of the dye-woods. Sometimes the cotton is boiled in a bath of the wood when it takes up some of the dye-wood, next there is added alumina acetate or tin crystals and the dyeing is continued when the colour becomes developed and fixed upon the cotton.
Iron may be used as a mordant for any of these dye-woods but it gives dull sad shades.
Chrome mordants can also be used and these produce darker shades than tin or alumina mordants.
As practically all these dye-woods are now not used by themselves it has not been deemed necessary to give specific recipes for their application, on previous pages several are given showing their use in combination with other dyes.
The dye-stuff Dinitroso-resorcine or Solid green O is used along with iron mordants for producing fast greens and with chrome mordants for producing browns to a limited extent in cotton dyeing. The following recipes give the details of the process.
Green.—Steep the cotton yarn or cloth in the following liquor until well impregnated, then dry: 3 gallons iron liquor (pyrolignite of iron), 22° Tw. gallons of water, ¾ gallon acetic acid, 12° Tw., 2 lb. ammonium chloride. Then pass the cotton through a warm bath of 3 oz. phosphate of soda and 4 oz. chalk per gallon, then enter into a dye-bath containing 6 lb. Solid green O. Work as described for dyeing alizarine red. For darker greens of a Russian green shade use 10 lb. of solid green O, in the dye-bath.
Brown.—A fine brown is got by steeping the cotton in a bath of 8 lb. Solid green O, 6¾ gallons water, 1½ gallons ammonia and 2 lb. acetate of chrome; dry, then pass through a soap-bath, wash and dry.
Deep Olive Brown.—Mix 8 lb. Solid green O and 4½ lb. borax with 6 gallons water, add ½ lb. Turkey-red oil, 5 lb. ammonia, then 2 gallons water and 1½ lb. copper-soda solution and another 2 gallons water. Steep the cotton in this, dry, soap well and wash. The copper-soda solution is made from 10 lb. chloride of copper (75° Tw.), 5 lb. tartaric acid, 12 lb. caustic soda (75° Tw.) and 4 lb. glycerine.
Khaki.—Make the dye liquor from 14 lb. Solid green O, ½ lb. Alizarine yellow N, 1 lb. caustic soda (36° Tw.), ½ lb. Turkey-red oil and 8 gallons water. To this add 2½ lb. acetate of chrome (32° Tw.), 2¼ lb. copper-soda solution and 4 gallons water.
Sage Green.—Use 1¼ lb. Solid green O, 3 lb. caustic soda (36° Tw.), ½ lb. Ceruleine, ½ lb. Turkey-red oil, 1 gallon water to which is added 2½ lb. acetate of chrome (32° Tw.) and 2¼ lb. copper-soda solution dissolved in 4 gallons water.
Pale Brown.—Use 4 lb. Solid green O, 2½ lb. borax, 3 lb. ammonia, ½ lb. Turkey-red oil, 6 gallons of water and 1½ lb. copper-soda solution dissolved in 2 gallons water.
Pale Fawn Brown.—The dye-bath is made from ½ lb. Alizarine, 1¼ lb. Solid green O, 1½ lb. borax, ½ lb. Turkey-red oil and 5 gallons of water to which is added 1½ lb. acetate of chrome (32° Tw.), 1½ lb. copper-soda solution and 4 gallons water. In all cases the cotton is steeped in the dye liquors until thoroughly impregnated, then the excess liquor is wrung out, the cotton dried, then passed through a soap bath, washed well and dried.
Dark Brown.—Place the cotton in a lukewarm bath of 25 lb. cutch and 1½ lb. copper sulphate; work for half an hour, then steep for six hours, then lift, wring and enter into a bath of 3¼ lb. bichromate of potash at 160° F. for twenty minutes. Then wash and dry.
Yellow Brown.—Make a bath with 14 lb. cutch and ½ lb. copper sulphate; work in this bath for four hours at 120° F., then pass into a bath of 2 lb. copperas and ½ lb. chalk, work for half an hour in the cold, then pass into a hot bath of 2½ lb. bichromate of potash at 150° F. for half an hour.
Dark Brown.—Make a dye-bath with 15 lb. cutch, 2 lb. logwood extract and 2 lb. fustic extract; work the cotton in this at 160° F. for three hours, then pass into a cold bath of 1 lb. copperas and ¼ lb. chalk for half an hour, then into a bath of 3 lb. bichromate of potash for half an hour at 150° F., then wash and dry.
By the action of nitrous acid upon the salts of the primary organic amines the so-called diazo compounds are formed. An example of this important process is that of nitrous acid on aniline hydrochloride shown in the following equation:—
C6H5NH2 + HCl + HNO2 2H2O + C6H5N:NCl Hydrochloric acid Nitrous Water, Diazo-benzene aniline, acid, chloride.
These diazo compounds are distinguished by their active properties, especially in combining with amines in acid solutions, or with phenols in alkaline solution to form the azo dyes, thus diazobenzene chloride will combine with naphthol to form naphthol-azo-benzene, thus:—
C6H5N:NCl + C10H7OH + NaOH = Diazo-benzene chloride, Naphthol, Caustic soda.
C10H6OHN:NC6H5 + NaCl + H2O Naphthol-azo-benzene, Salt, Water.
These azo compounds are coloured, but are perfectly insoluble in water, alkalies, or acids; on the other hand the sulphonates of these bodies are easily soluble and form the numerous azo dyes now so largely made and used in wool and silk dyeing, but which on account of their being sulphonates cannot be used for cotton dyeing.
Methods have been devised for producing the insoluble azo colours direct upon the fibres. They are also called naphthol colours from the use of beta-and alpha-naphthol in their production. Although these azo dyes, when produced on the fibre, do not possess the fastness of the alizarine dyes, yet, on account of their cheapness and relative great fastness to soap and the action of sunlight, they are better than many of the newer cotton dyes.
By this method (first introduced in England by Holliday) colours of exceptional brightness and fastness can be obtained which were not obtainable with the dyes then known. Those which are obtained from phenols are of the first importance.
The Diazotisation of the Amido Bases.
With most bases this must be accomplished as cold as possible below 65° F. At a higher temperature, and when allowed to stand, most diazo compounds decompose quickly with evolution of nitrogen, which decomposition results in the mixture losing its power of producing colour, or at the most gives unsatisfactory results. For this reason it is therefore always necessary to work as cold and as quickly as possible.
The amido-azo bodies, whose compounds with the phenols are also distinguished by their great fastness, are in this respect an exception. They can be diazotised at the ordinary temperature, and their diazo compounds are much stabler than those, for example, of alpha-and beta-naphthylamine or of aniline, which must always be used as quickly as possible.
From anisidine, phenetidine and amido-diphenylamine, still more stable diazo compounds can be obtained, but the prices of these bases are rather high, and the colours produced with them are not fast to light.
The cheapest and most convenient method of obtaining nitrous acid for diazotising is by the action of a mineral acid, preferably hydrochloric acid, upon nitrite of soda.
For diazotising one molecule of base requires one molecule of hydrochloric acid to form a salt of the base, a molecule of nitrite of soda, and another molecule of hydrochloric acid to decompose the nitrite. The diazotisation is better carried out and the diazo solution rendered more stable if another molecule of hydrochloric acid and an excess of nitrite of soda are used. The presence of an excess of nitrite can be determined by testing the diazo solution with potassium iodide starch paper, which in the presence of excess of nitrite gives the blue iodine starch reaction.
In carrying out the diazotisation, the base is first dissolved in the whole amount of hydrochloric acid which has to be used, and the solution is filtered. The diazotisation takes place in the manner shown in the equation:—
The bases which form salts soluble with difficulty, such as nitroaniline and the amido-azo bodies, offer special difficulties in diazotising.
It has been found that the operation with these is best carried out if the chemically pure bases in paste form are mixed with the requisite amount of nitrite, and the diluted paste then poured into the hydrochloric acid.
It has been found by experience that the colour is developed much brighter upon the fibre when the diazo solution contains acetic acid and no free mineral acid. However, the diazotisation is better carried out with hydrochloric acid, and the presence of the latter is necessary to give stability to the solution. If before the diazo solution is used a quantity of acetate of soda be added to it, the free hydrochloric acid liberates acetic acid from the acetate, and the chloride of the diazo body changes into its acetate. It is better to add an excess above the two molecules of acetate of soda which are required.
The combination when aniline and beta-naphthol are used, as the amine and phenol respectively, is shown in the following equations:—
NaOH = 2NaCl + C6H5N:NC10H6OH + H2O Caustic soda, Benzene- azo-naphthol, Water.
Or, with naphthylamine and naphthol, thus:—
C10H7N:NCl + C10H7OH + NaOH =
By the action of nitrous acid upon amido-azo bodies a group of bodies called diazo-azo compounds are obtained which contain the group N:N twice over, thus:—
When this compound is combined with naphthol diazo-azo dyes are produced.
C6H5N:NC6H4N:NC10H6OH. Benzene-azo-benzene-azo-naphthol.
The molecular weights of the bases, phenols and chemicals employed are the following:—
1. Hydrochloric acid, HCl—36.5. 2. Caustic soda, NaOH—40. 3. Nitrite of soda, NaNO2—69. 4. Acetate of soda, NaC2H3O23H2O—136.
1. Commercial hydrochloric acid at 32° Tw. contains about 365 grams of HCl in a litre, or 3½ lb. in a gallon.
2. The commercial 77 per cent. soda must always be used, and for practical purposes it may be taken as pure. It is best to make a solution which contains 160 grams NaOH in a litre of water.
3. The nitrite supplied is almost chemically pure, and is easily soluble in water. In order to make a solution 140 or 290 grams are dissolved per litre.
4. Crystallised acetate of soda contains 3 molecules of water of crystallisation, and is usually somewhat moist. Instead of 136 grams 140 are taken to allow for moisture. The amount is dissolved in about 500 cubic centimetres of water.
Bases.
1. Aniline, C6H5NH2—93.
2. Toluidine, C7H7NH2—107.
3. Alpha-and beta-naphthylamine, C10H7NH2—143.
4. Para-or meta-nitroaniline, C6H4NO2NH2—138.
5. Nitro-para-toluidine, C7H6NO2NH2—152.
6. Amidoazobenzene (base), C6H5N:NC6H4NH2—197.
7. Orthoamidoazotoluol (base), C7H7N:NC7H6NH2—225.
8. Alpha-or beta-naphthol C10H7OH—144.
Example of Quantities Taken.
Applying the principles which have just been described to the dyeing of cotton, it is found that the cotton may be dyed by taking the base and preparing the diazo body, impregnating the cotton with this, and developing the colour by passing into a bath of the phenol. On the other hand, the cotton can be prepared with the phenol and the colour developed by passing into a bath of the diazotised base, and practice has shown that this latter proceeding is the best. Practically the only phenol that is used is the beta-naphthol; alpha-naphthol is occasionally used, but not often.
The purer the beta-naphthol the better, especially for producing the paranitroaniline red. Various preparations of beta-naphthol have been brought out by colour makers.
The process of dyeing cotton with a naphthol colour takes place in two stages, the first being the grounding or preparing with the naphthol, the second the developing with the diazotised base. Some of the effects which can be obtained from the two naphthols and various bases are given in the following table:—
Base. With beta-naphthol, gives With alpha-naphthol, gives
5. Nitroparatoluidine, Orange; Very bright catechu.
6. Alpha-naphthylamine, Bluish claret red; Reddish puce.
7. Beta-naphthylamine, Turkey red; "
8. Amidoazobenzene, Red; "
9. Orthoamidoazotoluene, Yellowish claret red; "
By mixing alpha-and beta-naphthols together a variety of grenat and claret reds and browns can be obtained.
With regard to the fastness of the shades produced the following may be considered:—
The samples were tested for fastness to light by exposing them for nine days with the following results:—
Fast.
Combination of B- Naphthol with Nitroparatoluidine.