Online Encyclopedia

STYLES OF

Online Encyclopedia
Originally appearing in Volume V26, Page 705 of the 1911 Encyclopedia Britannica.
Spread the word: del.icio.us del.icio.us it!
STYLES OF PRINTING The widely differing properties of the hundreds of colouring matters now on the market give rise to many different styles of textile-printing. Generally speaking, these fall into the following four great divisions: (I) Direct printing. (2) The printing of a mordant upon which the colour is after-wards dyed. (3) The discharge style. (4) The resist or reserve style. The fact that each of these divisions is further sub-divided into many smaller divisions renders it out of the question to give more than a few typical examples of the various styles they include. (I) Direct Printing.—This style is capable of application to almost every class of colour known. Its essential feature is that the colouring matter and its fixing agent are both applied to the fabric simultaneously. In some instances the fabric requires to be previously prepared for certain of the colours used along with those characteristic of the process; but this is one of many cases where two styles are combined, and it must be classed with the one which it most resembles. (a) Application of Mordant Dye-Stuffs.—Mordant colours include both artificial and natural dye-stuffs (see also under DYEING), the most important of all being alizarine, an artificial preparation of the colouring-principle of the madder root. With different metallic oxides alizarine forms different colour-lakes all exceedingly fast to light and soap. Aluminium mordant gives red and pink lakes; iron mordant, purples and lavenders; chromium yields maroons; and uranium gives grey shades. Mixture of iron and aluminium produce various tones of chocolate and brown. In addition to alizarine the following are a few of the more important mordant dye-stuffs employed in textile-printing: Alizarine orange with aluminium and chrome mordants for orange and warm brown shades respectively; alizarine bordeaux, with alumina, for violets; alizarine blue with chrome and zinc for quiet blue shades; coeruleine and alizarine viridine for greens and olives with chromium mordants; gallocyanine, chrome violet blue, alizarine cyanines, &c., with chromium for various shades of blue and violet; alizarine yellows and anthracene brown for yellows and fawn shades respectively with either aluminium or chrome mordants. The natural dye-stuffs belonging to this series are chiefly: logwood, with chromium and iron mordants, for blacks; Persian berries and quercitron bark, with aluminium, tin and chromium mordants, for colours ranging from brilliant yellow to quiet old golds and browns; catechu, with chromium, for very fast dark browns; and, occasionally, in mixtures, sapan-wood, peach-wood, Brazil-wood, and divi-divi extracts with any of the above-mentioned mordants. The mordants are mostly in the form of acetates which are stable in the cold but decompose. during the steaming process, and combine as hydroxides with the colours, forming and fixing on the fabric the insoluble lake.699 Alizarine reds and pinks are the most complicated of the mordant colours. requiring for their proper production the addition of brightening agents, such as oxalate of tin, oils, tartaric acid, and also acetate of lime. This also applies to alizarine orange, but all the other colours are very simple to compound and are stable for a long time after making. Reds, pinks and oranges are best prepared freshly each day; their constituents are liable to combine if the colour stands twenty-four hours before printing. The following types of recipes will give some idea of the way in which colours are mixed : Red. 62 gallons thick starch and tragacanth paste. I4 „ alizarine (20 per cent. commercial paste). nitrate of alumina, 18° Tw. acetate of lime, 28° Tw. oxalate of tin, 1o° Tw. I „ lo per cent. solution of tartaric acid. Pink. 62 gallons starch-tragacanth paste. „ blue shade alizarine (20 per cent. paste). „ sulphocyanide of alumina, 18° Tw. e acetate of lime, 28° Tw. oxalate of tin. citrate of alumina, 40° Tw. For reds and pinks the nitrate, sulphocyanide and citrate of alumina are generally preferred in practice to the acetate though the latter is also largely used. Oranges from ;alizarine orange are made similarly. Purple. 9* gallons starch paste. I- „ blue shade alizarine, 20 per cent. s „ acetic acid. 1 acetate of lime, 28° Tw. e I- acetate of iron, 24° Tw. Maroon. 51 gallons paste. I „ alizarine, 20 per cent. 4 „ acetate of chrome, 32° Tw. acetate of lime, 28° Tw. Blues and the other colours are made by leaving out the lime in the last recipe and replacing the alizarine with another colour. Alizarine Blue. z lb alizarine blue shade (powd.). (Light Shade.) 1 gallon water. 31 „ thick paste. 11 „ acetate of chrome, 400 Tw. Logwood and other natural colours are specially boiled. Logwood Black. 115 lb starch. to „ British gum. 42 gallons water. 4 acetic acid. 11 „ logwood extract, 48° Tw. , quercitron extract, 48° Tw. Boil, cool and add: z lb red prussiate of potash. gallon water. 2 acetate of chrome, 40° Tw. 2 oz. chlorate of potash. Quercitron Yellow. IZ gallons quercitron extract, 48° Tw. 61 , water. 11 lb starch. Boil, cool and add : gallon acetate of chrome, 3o° Tw. The proportions here given are liable to variations according to circumstances. Indeed, no two works employ quite the same recipes, although the proportion of mordant to dye-stuff is pretty generally known and observed. After printing, the goods are dried, steamed for one hour, and then washed and finished. (b) Application of Basic Aniline Dye-Stuffs.—These colours all form insoluble lakes with tannic acid; hence tannic acid is the common fixing agent of the group. Arsenic in combination with alumina also gives basic-colour lakes, but their poisonous character and their inferior fastness to most reagents considerably limit their application. The more important basic dye-stuffs are: methylene blue, methyl violet, rhodamine, auramine yellow, safranine emerald green and indoine blue. Most of them are fairly fast to soaping, but towards the action of light they vary a good deal, methylene blue being perhaps as good as any, and the malachite greens the least stable. Their application is simple. A solution of the colouring matter is added to the requisite quantity of starch paste or gum, and, when well mixed in, the tannin is added in the form of a solution also. If desired they may be boiled up like the extract dye-stuffs (logwood, &c.), but this is not necessary unless large quantities are required, when it would be more convenient to boil the whole at once than to mix small batches by hand. Methylene blue will serve as a type of the method by which all basic colours are compounded. Blue. 2 gallons methylene blue, to per cent. solution in water and acetic acid. 6 „ thick starch paste. tragacanth mucilage. „ tannic acid solution, 50 per cent. to gallons. All other basic colours are made up for printing in a similar way by replacing the blue with the required dye-stuff. After printing, goods containing basic dyes are " steamed,” and passed through a solution of tartar emetic, or other salt of antimony, whereby an insoluble double tannate of antimony and colouring matter is formed, which constitutes a much faster colour than the single tannate of the dye-stuff. Basic colours may be printed along with " mordant " and albumen colours. (c) Application of Direct Dyeing Colours.—These colours have a natural affinity for the cotton fibre and therefore require no mordant. They are not very " fast,” however, and, though used enormously in the dyeing of plain shades, they find but little employment in printing except for the tinting of printed goods, and for the " crepon " style, where the colours must be able to withstand the action of caustic soda. They are usually printed with the addition of a slightly alkaline salt (phosphate of soda) and sulphate of soda. Amongst the hundreds of direct colours equally suitable for printing mention may be made of erica for pinks; diamine sky-blue for blues; diamine violet, and diamine, chrysamine, chloramine and dianil yellows. In fact, most of the benzidine, diamine, diaml and Congo dye-stuffs can be used for printing, but with the exception of the yellows none of them will resist the action of light and washing to anything like the extent that " mordant " and basic colours will. The general formula for printing these colours is as follows 4 oz. colouring matter. } gallon water. , starch or tragacanth thickening. 4 oz. phosphate of soda. 2 oz. sulphate of soda. After printing, with direct colours, the goods are first steamed, then slightly washed in a weak tepid soap solution and finally finished. (d) Application of Pigment Colours.—Before the introduction of coal-tar colours, pigments and lakes played a much more important part in textile-printing than they do at present, though they are still largely used for certain styles of work. They form a series of colours more difficult to work than those already mentioned, but very fast to soap and light. Pigment colours, being insoluble mineral precipitates or lakes, can only be fixed on the fibre mechanically; consequently they require to be applied in conjunction with vehicles which cause them to adhere to the fabric in much the same way that paint adheres to wood. Of these vehicles, albumen is the most important and the best. It forms a smooth viscous solution with cold water, mixes readily with all the colours used in pigment printing, and possesses the property of coagulating when heated to the temperature of boiling water. When cloth printed with colours containing albumen is passed through hot steam or hot acid solutions, as in the indigo discharge style, the albumen coagulates, forming a tough insoluble colloidal deposit, which firmly fixes on the fibre any colour with which it is mixed. The colours chiefly employed in pigment printing are: chrome yellow and orange, Guignet's green or chrome green; artificial ultramarine; lamp black for greys; the various ochres for golds and browns; zinc oxide; vermilion and its substitutes, and occasionally lakes of the natural and artificial colouring matters. All these bodies are applied in exactly the same way and may be mixed together in any proportion to form compound shades. The amount of albumen necessary to fix them varies according to the depth of shade required (between to and 25 per cent. of the total weight of the made-up printing colour), and although it is usually considered in text-books as a thickening agent it is rarely used as such in practice on account of its expense. As a rule the colouring matter is beaten up into a smooth paste with the necessary quantity of a strong solution of albumen and then reduced to its proper strength by the addition of tragacanth mucilage or starch paste. The main factor in the successful working of pigment colours is their fineness of division; the finer they are the better they print and the more beautiful is their quality of colour. If they are too coarse they give rise to innumerable defects, either by sticking in the engraving or by scratching the roller, or, if they print at all, by yielding uneven masses of colour, granular and speckled in appearance and quite unsaleable. Even when finally ground they are liable to clog the engraving of the rollers—a defect which is more or less successfully overcome by replacing the colour-furnishing roller in the printing machine by a revolving brush. The following formula of dark ultramarine blue will serve as a type of all other pigment printing colours:—24 lb artificial ultramarine. Place in grinding machine and beat up gradually with 41 gallons 40 per cent. blood albumen solution. „ tragacanth mucilage, 8 oz. per gallon. s}a A Make to 8 gallons with tragacanth or water, and grind the whole until perfectly homogeneous. The small quantities of ammonia, turpentine, glycerin and oil are added to prevent the colour from frothing during the printing process. Chrome yellows and oranges are frequently mixed with a little cadmium nitrate to counteract the action of sulphuretted hydrogen on the lead salts. The great disadvantage of pigment colours is that although extremely fast to light and soap they are liable to rub off, if the fabric is subjected to much friction in washing. They also impart considerable stiffness to the goods, and for these two reasons they are therefore restricted to the printing of small patterns, or are used for such styles as window-blinds where the stiffness is not objectionable. In very pale shades they are used for printing the grounds or " blotches " of multicolour patterns, the small quantity of albumen they then contain being insufficient to appreciably affect the softness of the cloth. In several discharge styles too —notably indigo—they find extensive use, and on the whole they constitute a most useful class of colours. (e) Application of Indigo.—Indigo is printed on cloth by several different methods, the chief of which are: (I) Schlieper and Baum's glucose process; (2) the hydrosulphite process; and (3) the production of indigo on the fibre itself by means of Kalle's indigo salt and several other artificial preparations. The first and second processes depend upon the facts that indigo in presence of caustic alkalis may be converted into indigo-white by reducing agents, and that the indigo-white, being soluble in the alkali, penetrates into the fibres of the cloth, where it is subsequently re-oxidized to its original insoluble state. In Schlieper and Baum's process (also known as the glucose process) the cloth is first prepared in glucose, and then printed with a colour containing finely ground indigo, caustic soda and dextrine thickening (also made with caustic soda). After printing, the cloth is " aged,” that is, passed through damp steam for a few minutes to effect the reduction and solution of the indigo, and is then hung up in a cool chamber for a day or two, in order to re-oxidize the indigo-white to indigo by the action of the oxygen in the air. A wash in cold water finally completes the fixation of the indigo, `and the cloth may then be soaped and finished as usual. The cloth is prepared by running through a box containing a 3o per cent. solution of glucose in water; the excess is squeezed out in a mangle, and the cloth dried. It is then printed with the following colours according to shade required: Dark Medium Light Blue. Blue. Blue. Alkaline dextrine paste 7i gals. 8 gals. 8 gals. Caustic soda, 38° Tw. . . i; „ 4 Indigo 20 per cent. paste ,, ; to gals. to gals. to gals. The printed goods should be dried quickly, and " aged " as soon as possible to prevent the absorption of carbonic acid gas from the air, after which the operations already mentioned may be proceeded with at leisure. The well-known blue and red pattern is produced by this process, the only difference being that, instead of white cloth, turkey red dyed cloth is used, the strong alkali dissolving out, or " discharging,” completely the colour from those parts of the cloth upon which it falls, and leaving the indigo as a blue pattern on a red ground. In the hydrosulphite process, which is much quicker than the preceding, the reducing agent, the indigo and the alkali are all printed together on unprepared white cloth. The goods are then " aged," and allowed to lie a short time, after which they are washed-off in cold water first, until the indigo is thoroughly re-oxidized, and then in hot water or soap. The hydrosulphite printing colour is as follows: 200 parts hydrosulphite N.F. (or too of the concentrated pro-duct). 450 „ alkaline dextrine paste. S 150 „ indigo 20 per cent. paste (ground up in gum). 1 Zoo , alkaline dextrine paste. Thickening 150 parts dextrine or British gum. 850 ,, caustic soda, 70° Tw. Print, dry, " age " and wash off in a copious supply of cold ;water ammonia. glycerin. turpentine. olive or cotton-seed oil. Grind till perfectly smooth in a mill and then add: too parts ice. 20 ,, nitrite of soda of 93 per cent. strength. 8o „ water. starch and tragacanth thickening. benzine. acetate of soda. The third process with Katie's salt is not properly speaking the printing of indigo, but of a special preparation capable of forming indigo when treated with caustic alkalis. The salt is merely , dissolved and thickened with gum or starch, printed, and then passed direct through a solution of caustic soda, when the indigo is immediately developed. Instead of being passed through the alkali, which is apt to cause the colour to run before it is properly developed, the cloth is more commonly printed with thickened caustic soda, whereby the indigo is equally well produced without any fear of " running." Besides indigo, other vat dye-stuffs, such as indanthrenes, the algol, helindone and ciba colours, thioindigo scarlet, &c., are also printed largely at the present time, yielding colours of hitherto unattained fastness to washing and to light. (f) Insoluble Aso-Colours.—These colours do not exist as such, but require to be produced on the fibre itself from their components. They form a range of exceedingly fast colours, including orange, red, pink, maroon, brown, chocolate, blue and black, and are produced by the combination of various diazo-bodies with phenols, the most important of which latter is 0-naphthol (beta-naphthol). In practice their application is briefly as follows:—The bleached cloth is prepared in a solution of 0-naphthol in caustic soda (naphtholate of soda), then gently dried and printed with the thickened diazotized amine required to produce the desired shade. The printing colour must be cooled with ice to prevent its decomposition; hence such colours are sometimes known as " ice colours." The two colours most extensively used are para-nitraniline red and a-naphthylamine maroon, both of which are bright fast colours, only equalled by turkey red and madder chocolate for general usefulness. On 0-naphthol prepare the following colours may be obtained: Red with paranitraniline. Maroon with a-naphthylamine. Orange with orthonitrotoluidine. Pink with azo pink 2 B. Chocolate with benzidine. Brown with benzidine and orthonitrotoluidine. Blue with dianisidine. Black with dianisidine and benzidine. Other naphthols and other bases give a still greater variety of shades. The naphthol prepare requires to be freshly made, and the cloth prepared with it carefully dried, if good results are to be obtained. Paranitraniline is made up for printing by dissolving in hydrochloric acid. Nitrite of soda is then added, and, after standing a short time to complete the reaction, the resulting diazo-solution is mixed with thickening, and acetate of soda is then added to neutralize any free mineral acid still remaining, the presence of which would prevent the formation of the colour. In practice the following formulae have given good results (I) PARANITRANILINE RED Prepare the bleached cloth in: 47 parts-naphthol. 3 „ naphthol R. 107 „ caustic soda, 5o° Tw. 400 „ hot water. 10 „ tartar emetic. 12 ,, tartaric acid. Make up to woo parts with hot water. The cloth is passed through a trough containing this solution, the excess is squeezed out between two wooden rollers, and the cloth is gently dried and then printed with: 36 parts paranitraniline C. Too „ ice. 1 loo „ hydrochloric acid, 30° Tw. 70 „ water. Mix and add quickly: 24 parts nitrite of soda, 93 per cent. 70 , water (cold). And just before printing add further: too parts acetate of soda. 100 „ ice in large pieces. 400 „ tragacanth mucilage, 12 per cent. Print, dry and wash. A similar prepare without the naphthol R. may be used for a-raphthylatnine maroons, the printing colour for which is made up as follows 36 parts a-naphthylamine. 93 „ hydrochloric acid, 3o° Tw. 171 „ tragacanth mucilage. Print, dry and wash. Immediately these diazo-colour pastes come in contact with the naphthol-prepared cloth the colour itself is formed and fixed and requires no further treatment except that of washing to remove the naphthol from the unprinted parts of the cloth. The other bases are diazotized in precisely the same way, the quantities of acid and nitrite of soda being varied according to the molecular weights of each base. Several processes of printing azo-colours directly, without any previous preparation of the cloth, have been proposed, but they are not in general use as yet ; those which have passed the experimental stage are not very successful on the large scale, and have, for the most part, been abandoned. (g) Application of Sulphur Dyes.—Of late years the class of colours known as " sulphur colours " have assumed a prominent place in textile-printing. They are really direct dyeing colours, but their special properties entitle them to be classed apart from those usually known under this name. There are now an enormous number of sulphur-colours on the market under many different names, but, as they are all similar in general properties, it is needless to mention more than one series. The " thiogen colours " of Meister, Lucius and Bruning will serve as well as any to exemplify the application of these dye-stuffs in printing. They comprise yellows, golds, browns, violets, blues, greys and blacks, all fairly, and some very, fast to light and soap, and, under proper conditions, easy of application to a variety of styles. The general recipe for printing is as under 30 parts by weight of colouring matter. 50 glycerin. 8o „ „ water. 1 50 , ,, china clay beaten up with 5o water. 40 „ „ concentrated hydrosulphite N.F., 5o per cent. solution. alkaline British gum thickening. I000 This paste is printed on unprepared bleached cloth, gently dried and then passed through a rapid steam ager, in from 4 to 7 minutes in dry steam at 212° F. to 220° F. (or twice for 3 minutes), after which the cloth is passed in the open width through the washing and soaping machines, and finally dried up and finished. The sulphur colours may be used in combination with the azocolours, on naphthol-prepared cloth, for the production of multi-colour effects, and are eminently adapted also to the production of coloured discharges on paranitraniline red and the direct-dyeing colours. (h) Aniline Black.—Aniline black was discovered and first used by Lightfoot in 1863. It is one of the fastest blacks known, and is equally useful for direct printing by itself, and for working along with printed mordants and discharge pastes. Aniline black is formed by the oxidation of aniline. As a rule the oxidation of the aniline is brought about by means of sodium chlorate in presence of suitable oxygen carriers such as copper sulphide, vanadium chloride or potassium ferrocyanide. Copper and vanadium blacks are usually developed after printing by being aged in a moderately warm room for a day or two, when they become converted into " emeraldine,” at which stage they are taken down, and passed through a hot solution of bichromate of potash to complete the oxidation of the aniline. Great care is required in printing these two blacks, as if overdried they take fire and have occasionally caused considerable damage to buildings in consequence. The blacks made with ferrocyanide, on the contrary, may be printed in conjunction with " steam " colours, and, after a preliminary passage through a rapid steam ager, and an ammonia " gassing " box, will withstand the long steaming necessary for alizarine colours. A copper aniline black may be made as follows: ( 15 lb starch. j( 8 lb British gum or dextrine. 54 gals. water. 4 lb chlorate of soda. 4 gal. olive oil. Boil, cool and add : 8 lb aniline salt. 3 lb aniline oil. 5 lb sulphide of copper (precipitate pressed to a 30 per cent. paste). _1 gal. water. „ „ 400 25 75 I000 700 ,, This black may be either hung to develop, which is the safer course, or, if printed in fine shirting patterns, it may be " aged " through steam for 2 to 3 minutes. Whichever method is adopted the printed cloth must afterwards be passed through hot bichromate —” chroming "—and then well washed. The following ferrocyanide black works well in practice: To lb starch. 2 lb British gum. 6 tb yellow prussiate (ferrocyanide) of potash. 7 gals. water. Boil, turn off the steam, and add: 2; lb chlorate of soda in powder. Cool and add : 8; lb aniline salt. Print, age 4 minutes through the rapid ager, chrome, wash and soap. If printed with alizarine steam colours it must be passed through ammonia vapour after " ageing," and then be steamed for one hour before chroming and washing. Sometimes the chroming is omitted, but the colour is then apt to become green after a short time owing to the action of sulphur dioxide present in the air. Aniline black is now used almost exclusively for printing along with mordants for the madder style, and for black ground goods that were formerly dyed with logiiood on an iron mordant. Shirtings and all single-colour black dress goods are also executed in aniline black, which is faster to light, washing, and perspiration than any other black except some of the sulphur blacks. (2) Printing of Mordants.—This, the second of the great styles of textile printing, was, at one time, the most extensively practised of all, and is still the most important for all classes of work whereits weight of arsenious acid, or " white arsenic," a substance which retards its oxidation. For this purpose the goods are printed with either aluminium or iron acetates, and hung or " aged " for 2 to 3 days in a brick chamber containing moist air at about 30° C. dry bulb, and 27° C. wet bulb thermometer. In this operation the " ageing " (which is really the volatilization of the acetic acid, leaving the hydrated oxide on the fibre) goes on slowly and evenly. After hanging, the last traces of acid are removed and the hydroxide thoroughly fixed by " dunging," a process in which the goods are passed through a mixture of cow-dung and chalk at a temperature of about 50° C. In this "dunging ' bath they are worked altogether, about 11: hours, at the end of which the mordants are thoroughly fixed, and all the thickening agents perfectly eliminated, thus leaving the cloth in the best condition to absorb the dye-stuff. The dyeing is carried out by working the goods at 60° C. in a mixture of alizarine, a little chalk, and glue size for i to q. hours. They are then well washed, soaped, and the whites cleaned by a passage through weak bleaching powder solution, followed by a passage through steam. Further soaping and washing is then resorted to until the goods are quite clear and bright. In the case of cloth dyed in red and pink alone the goods after dyeing are well washed, passed through a bath of alizarine oil containing oxalate of ammonia, and then steamed for one hour at 15 lb pressure. This brightens the colours by removing the brown appearance they possess after dyeing. When reds are associated with chocolates and purples, however, the oiling process must be carefully conducted, otherwise the two latter suffer; frequently it is omitted altogether, the brightening being effected by vigorous soaping. By printing the following mordants a six-colour design may be produced with a single dye-stuff and in one dyeing: Red. Pink. Chocolate. I Dark Purples. Violet. Black. Aluminium acetate, 6° Tw. i2 gals. 3 gals. toe gals. gal. ; gal. 8 gals. Black liquor, 24° Tw. Water .. 8 gals. .. 11 „ Ili 4 British gum .. 36 lb .. .. 36 lb' Acetic acid al. . . .. . . Tin crystals 1 a lb '-- lb . Cotton-seed oil ; gal. .. ; gal. ; gal. .. ; gal. Starch 16 lb .. i6 lb 16 lb .. i6 lb the fastest colours are required. It may be conveniently divided into two branches: (a) the madder style, and (b) the printing of other mordants such as chrome, tannic acid, $-naphthol, &c. (a) The Madder Style.—In this style the only mordants used are those of aluminium and iron. Aluminium alone yields various shades of red and pink when dyed up in madder, or its artificial competitor alizarine. Iron alone yields with the same dye-stuffs shades varying from black to the palest lavender. Iron and aluminium mordants in combination yield colours ranging in shade from claret through all gradations of bordeaux and maroon to the deepest chocolates, according to which of the two mordants predominates in the mixture. Browns and allied colours may be dyed on the same mordants with either nitroalizarine alone, or with alizarine itself mixed with dyewood extracts—logwood, Persian berry or quercitron bark, &c. Both aluminium and iron mordants consist of the acetates of their respective metals. The iron mordant which gives the best results is known as " black liquor." It is a crude acetate containing a good deal of organic matter which appears to regulate the speed of its oxidation and so produce much more level colours than have ever been obtained from any other iron mordant. Aluminium acetate in the pure state is also rarely employed, the crude commercial " red liquor " being found in practice to yield the best results, both as, regards colour and ease of working. The " red liquors " vary considerably in composition, some being normal acetates, others basic acetates, some normal sulphate-acetates, others basic sulphate-acetates, but their mode of application is always the same, that is, they are thickened, printed, aged and dyed in alizarine. If they are too basic they decompose on boiling, or on dilution, and become utterly useless; but this rarely happens nowadays and need not be further gone into. Many difficulties occur in the printing of mordants and their subsequent dyeing, but if the following points are observed most of them may be surmounted; (1) after printing the cloth must be gently dried, other-wise the mordants become dehydrated or " burnt," and instead of dyeing up evenly they appear patchy and very light in the over-dried parts; (2) the dye-stuff must not be used in excess; and (3) the temperature of the dye-bath must be kept as low as is consistent with the fixation of -the colour. If these last two points are neglected the unprinted parts of the cloth, which should remain a pure white when it is finished, will be soiled beyond repair unless indeed the " whites " are cleared at the expense of weakening the colour. Iron mordants especially are liable to unevenness due to the oxidation being too rapid; and as this defect is most noticeable in purples and lavenders, the pyrolignite of iron or " black-liquor " is frequently boiled for half an hour or more with 1 per cent. of The above mordants are printed on white bleached cloth, dried hung 2 to 3 days, " dunged," dyed, washed, well soaped and washed again; then "chemicked'' through weak bleaching powder solution, and finished. The " dunging " is performed in vats through which the cloth circulates continually during the operation. As a rule dunging is done twice, the second bath being weaker than the first. The vats or " becks " contain a mixture of Too gals. water io lb chalk 1st dunging. . 50 lb cow-dung at 60° C. Too gals. water 5 lb chalk 2nd dunging. 25 lb cow-dung Wash well after " dunging " and dye in alizarine, &c. The dyeing is carried out in large becks over which a roller or bowl revolves, equal in length to the beck. Over this roller the cloth is wound spirally in large loose loops so that one end of the loop is on the roller and the other dips into the dye liquor. When about 700 yds. of cloth have been entered in this way the two ends of it are knotted together, thus forming an endless rope which circulates continuously in and out of the dye-liquor. The vat or beck is then charged with alizarine, chalk and glue, the proportions varying according to the amount of space covered by the mordants on the cloth. If, for instance, half the surface is printed then the dye-liquor might be made up as follows, the quantities being calculated on the weight of the cloth 4 per cent. alizarine (blue shade), 20 per cent. ) in a sufficiency 11 „ acetate of lime, 28 Tw. of water. 10 glue solution, or size, 15 per cent. The goods are entered into this solution cold. The temperature is gradually raised to 60° C., and the dyeing continued at this for one hour or more. The goods are then washed in a similar machine, soaped well and finished off by drying. Aniline black may be printed along with " red liquor " and iron liquor, and many other modifications also employed, but the principle of dyeing is always the same. (b) The Printing of other Mordants.—Of these the most important are tannic acid, chrome mordants and 0-naphthol. For printing tannic acid the following is used: 5 lb tannic acid dissolved in 1 gal. acetic acid and added to 9 ,, starch and tragacanth paste. The goods are simply dried after printing and the tannic acid immediately fixed by passing through a solution of- ,2 oz. tartar emetic. t oz. chalk. ,i gal. water at 60° C. After washing they may be dyed up in any of the basic aniline colours. Various chrome mordants are employed in printing,, amongst which may be mentioned chromium chromate, and chromium acetate. The former is thickened with starch or gum, printed, and fixed by being passed through boiling sodium carbonate. The latter is applied in the same way but, after printing, is steamed before the carbonate treatment. Both these mordants are suitable for dyeing with any of the dyes mentioned under the direct printing of mordant colours, such as alizarine, alizarine bordeaux, coeruleine and the natural dye-wood extracts. They are dyed similarly to the madder colours, with an addition of glue size to preserve the white of the unprinted parts of the cloth. (3) The Discharge Style.—This style is now one of the most important produced. Its range is so extensive, and its modifications so numerous, that it is impossible to mention more than a few of its chief applications. It may be used for locally destroying either the colours dyed on cloth, or the mordants with which they have been previously prepared. In both cases the resulting pattern appears in white, or colours, on a full rich ground the beauty of which cannot be equalled by direct printing. The discharging agents consist of organic acids, caustic alkalis, oxidizing agents and reducing agents, each used according to the kind of colour or mordant to be discharged. (a) Discharge of Iron and Aluminium Mordants.--The cloth is padded with a solution of these mordants, dried in hot air, and then printed with thickened citric acid or acid citrate of soda mixed with china clay to prevent the pattern running. It is then passed through the rapid ager once or twice, " dunged," washed, and dyed in the usual way for madder colours. Wherever the discharge has been printed the mordant is dissolved out, leaving a white pattern on a dyed ground. (b) Tannate of antimony mordant is similarly discharged by printing on caustic soda. The goods are passed in like manner through the ager, well washed in water, and dyed-up in any basic aniline dye. (c) The chrome discharge is produced by padding the goods in chromium bisulphite; then drying them, and printing-on citric acid, or chlorate of soda and yellow prussiate of potash. They are then steamed, passed through chalk and water, well washed and dyed up in any mordant dye. (d) Turkey red may be discharged in both white and coloured patterns by either oxidizing agents or caustic alkalis. (I) The dyed cloth is printed with strong citric acid, or arsenic acid, at 180° Two, and then run through bleaching powder solution, whereby the printed parts are completely decolorized. If colours are required, the citric acid is mixed with lead salts and Prussian blue, and the fabric after passing through the bleaching powder solution, is further treated in a bath of bichromate of potash which forms with the lead salts the insoluble chrome yellow. Green is obtained by the combination of Prussian blue with the chrome yellow. Examples: White. 6 lb citric acid or tartaric acid. t gal. water. 4 lb British gum or dextrine. Boil together. Yellow. 15 lb British gum. 11 gals. dark British gum paste, 30 per cent. , water. 20 lb tartaric acid. 12 lb nitrate of lead. Print, dry, dischage through bleaching powder solution, 18' I'w., and chrome. (e) The dyed cloth is printed with strongly alkaline discharge pastes, passed through the " ager " two or three times, and then washed off in silicate of soda. If blue, yellow and green discharges are desired the dyed cloth must first be passed through glucose solution, well dried, printed with the colours, " aged," passed through silicate of soda, chromed in bichromate, well washed and dried. Examples: White. to lb stannous chloride dissolved cold in 8 gals. alkaline thickening. 2 ,, silicate of soda, 70° Tw. Blue. 15 lb indigo pure 20 per cent. paste. A. gal. turpentine. A „ glycerin. 1 „ British gum paste. 7 „ alkaline thickening. Green. 8 parts of the yellow without silicate. 1 part of blue. (f) Paranitraniline red is discharged by means of the new hydrosulphite-formaldehyde compounds. The dyed cloth is printed with the following: 25 lb hydrosulphite N.F. conc., or hydraldite conc. 11 gals. British gum paste. Heat till dissolved and add- - gal. glycerin. 41 „ starch-tragacanth thickening. After printing, age twice for 4 minutes through dry steam at 220° F., then wash well and soap. Coloured discharges are obtained by mixing hydrosulphite, tannic acid, aniline or phenol, and basic colouring matters together. Mordant dyes fixed with chromium acetate may also be used. On e-naphthylamine maroon the above discharge white requires the addition of induline scarlet, patent blue or anthraquinone, before it becomes effective, otherwise the procedure is the same as for paranitraniline red. (g) Indigo is usually discharged by oxidation. For this purpose the dyed cloth is printed in two different ways. Firstly, with chlorate of soda, and red or yellow prussiate of potash together with a little citric acid or citrate of soda; secondly, with chromate of potash. In the first instance, the cloth is " aged " through the rapid ager after printing, and, in the second, is passed through a vat containing hot sulphuric acid and oxalic acid. Coloured discharges may be obtained in both methods by adding albumen and pigment colours to the discharging agents. (1) Discharge by steaming: {12 lb citric acid, dissolve in: 7 lb caustic soda, 70° Tw., and add: 12 lb sodium chlorate. 5 gals. British gum paste. Heat till dissolved, cool and add : 1 gals. British gum paste. 2 lb yellow prussiate of potash. Print, steam and wash. Chlorate of aluminium is also used for this process, but it acts very energetically and is apt to tender the cloth. (2) Chromate discharge: White. 82 gals. British gum paste. 12 lb bichromate of soda. a gal. turpentine. Yellow. 32 lb chrome yellow pigment. 3 gals. 50 per cent. albumen solution. thick tragacanth mucilage. „ oil (vegetable). 12 lb bichromate of soda neutralized with gal. caustic soda, 70° Tw. a ,, water. Print, dry, pass through a " beck " (i.e. a bath) containing:—too gals. water. 50 lb sulphuric acid (168° Tw.). 50 lb oxalic acid. Then well wash and dry. With these oxidation discharges it is impossible to prevent the fibre being attacked in the discharged portions, with the result that it is partially converted into oxycellulose. Recently a method has been brought out for the production of a white discharge on indigo which is said to do away with the formation of oxycellulose and which consists in printing on a thickened solution of sodium nitrate and, after drying, running through sulphuric acid of 50° Tw. Another method of producing white discharges on indigo consists in printing the dyed cloth with hydrosulphite N.F., then steaming and running through a boiling solution of caustic soda. Good whites are thus obtained without the formation of oxycellulose, but the process is expensive. (h) Direct dyeing or substantive colours can be easily discharged with the hydrosulphite discharge used for paranitraniline red (see above). It must be reduced in strength to about one-fourth for dark shades, and much weaker for lighter colour& Direct colours were formerly discharged by stannous chloride or acetate, but the hydrosulphite has almost entirely displaced these salts for white discharges. (i) Discharges on manganese bronze are of little importance at the present time. They are effected by means of stannous chloride, colours being obtained by the addition of basic dyes and dyewood extracts. (j) Sulphur-colours, dyed basic colours, and some alizarine colours, are discharged with chlorate and prussiate like indigo. (4) The Resist or Reserve Style.—Reserves are substances which, when printed, prevent the fixation or development of mordants and colours subsequently applied, and are used to produce effects similar to those obtained by discharge printing. The principal reserves are those used for madder dyed goods, steam alizarine reds and pinks, steam basic colours, vat indigo blue, insoluble azo colours, sulphur-colours and aniline black. Yellow. 30 lb lead hydrated 50 per cent. 2 gals. water. „ silicate soda. 54 „ alk. thickening. Alkaline Thickening. 15 lb yellow dextrine. 8 gals. caustic soda, 100° Tw. (a) Reserves under Aluminium and Iron Mordants.—For the production of this important class of goods, use is made of the fact that alkaline citrates prevent the fixation of the mordants. The cloth is first printed with citrate of soda (or sometimes citric and tartaric acids for iron mordants), then dried, and again printed over the previous impression, with either a fine "all over " pattern or flat uniform ground, in iron or aluminium mordants. The fabric is then aged, " dunged," washed and dyed as already described, with the result that wherever the " reserve " of citrate or acid was printed a white pattern is left on a figured or plain ground. The fine patterns printed over reserves " are called " covers " and the plain grounds " pads,” hence the name " cover and pad " style in cases where, as frequently happens, a dark " cover " and a light " pad " are both printed over a white " reserve.” The " cover and pad " style is, for the most part, restricted to dyed alizarine purples under which red, black, dark purple and white can all be reserved at the same time, thus giving rise to very pleasing effects. For example: white cloth is first printed with four " colours,” viz., citrate of soda and citric acid for the white; log-wood and iron for the black; strong iron mordant for the purple; and aluminium acetate at 6° Tw. with 8 oz. per gallon of stannous chloride for the red. (The stannous chloride acts as a resist for iron mordants.) The whole is then " covered " in a fine pattern printed in a fairly strong iron mordant, dried, and again printed, in a very weak iron mordant, with a pad roller, that is, a roller which prints a uniform ground over the whole surface of the cloth. After this last printing, the cloth is " aged " for a day or two, by being hung as previously described, then " dunged,” washed and dyed in a blue shade of alizarine. When finally washed, soaped and " cleared " in bleaching powder solution the first printed pattern in white, red, black and purple is seen to stand out, clearly and sharply, from a figured background in two lighter shades of purple. This " cover and pad " style of reserve printing constitutes one of the staple processes of nearly all print-works, and is produced in enormous quantities for both home and foreign markets. Red is not often introduced as in the above example, the usual colours being white, black and two purples. The same method of working can be adopted with aluminium mordants for red and pink covers and pads, but they are better produced with the steam alizarine colours as below. (b) Reserves under Steam Alizarine Red and Pink.—In this case a reserve composed of citrate of chromium alone, or in conjunction with citrate of soda, gives the best results. The goods are first prepared in alizarine oil and then printed with the following: lo lb china clay. 2 gal. citrate of soda, 54° Tw. „ citrate of chromium, 42° Tw. water. z ,. 21 „ British gum paste. Blue. Yellow. Green. Pink. New methylene blue N. . 2 alb .. 2 lb I lb Auramine G. (B.A.S.F.) . . .. 2 lb I4 „ 2 gals. Brilliant green .. 2 gals. 2 gals. 2z lb Theoflavine T. . . 2 gals. 22 lb 2y lb IO Rhodamine 6 G. (extra) . 2i lb IO IO „ 2 gals. Acetic acid IO I a gals. 2 gals. I „ Citric acid 2 gals. I ,, I „ 2 , Starch I , 2 20 lb 20 lb Water . . . I2 „ 20 lb Tragacanth mucilage . 20 lb Tannic acid sol., 50 per cent, . Tin crystals Make up to . . lo gals. lo gals. Io gals. to gals, [TECHNOLOGY After printing the above, the goods are dried and again printed either with " cover " or " pad " or both, in alizarine pink, dried, steamed for i hrs., well washed and soaped. On leaving the steamer the parts printed with the resist are yellow, but become quite white on soaping. Like the purples, the alizarine pinks can be reserved in colours. For blue, green, yellow and violet the ordinary steam basic colours are used with additions of citric or tartaric acid. Example : S 7 lb china clay. j 2 gal. water. 6;, ,, British gum paste. 2 lb methylene blue. t lb citric acid. t gal. acetic acid. Boil, cool, and add i; gals. 50 per cent. tannic acid solution in acetic acid. Red with steam alizarine red; yellow with thioflavine in place of methylene blue in above; green a mixture of blue and yellow. These colours with the white reserve may all be printed at once. Then steam as usual, pass through a solution of tartar emetic and chalk, wash well and soap. (c) Reserves under Insoluble Azo-Colours.—These are based upon the action of stannous chloride, which prevents the combination between the $-naphthol and the diazo bodies by reducing the latter to hydrazines. The 0-naphthol prepared cloth is printed with the following colours, then dried and passed through diazotized solutions of paranitraniline for red grounds; a-naphthylamine for maroon; ortho-nitrotoluidine for orange, &c., &c. The cloth is then washed and soaped until the " ` whites " are clean. White Resist. 5 gals. gum senegal solution. 3o lb tin crystals. 5 lb tartaric acid. For heavy rollers this may be reduced with more gum. Potassium sulphite is also used as a white reserve under insoluble azo-colours with good results. (d) Reserves under Steam printed with:- - 20 lb china clay. 21 gals. water. . 15 lb British gum. 20 lb sodium tartar emetic. 20 lb zinc sulphate. All boiled well together, and then covered, or over-printed, with any steam basic colour—steamed one hour, passed through tartar emetic, then washed and soaped, when the reserve white above comes away, bringing along with it the colour printed upon it and leaving a white pattern on a printed ground. (e) Reserves under Vat Indigo Blue.—This was formerly a very important style, but at present is only used in special cases. Resist or reserve effects are obtained by printing the white cloth with oxidizing agents, &c., and subsequently dyeing it in the indigo vat. In addition to oxidizing agents the reserve pastes contain lead sulphate, barium sulphate, resins, fats and thickenings in various proportions. The following is a good white reserve: 15 lb flour. 6 gals. water. Boil, cool a little, and add 18 lb copper sulphate powdered. 22 lb copper nitrate, 90° Tw. 1 pint alizarine oil. Yellow. 2; gals. British gum paste. 33 lb lead sulphate, 66 per cent. paste. 18 lb zinc sulphate. 22 lb lead nitrate. Print the white and yellow, dry, dye in the indigo vat—sour slightly in sulphuric acid, wash, and pass into a hot solution of bichromate of soda, which develops the lead yellow. Reserve whites also contain lead salts when used for white alone, but obviously the white given is best suited to white and yellow reserves, as its soluble copper salts wash out before the " chroming " stage is reached. (f) Reserves under Sulphur Colours.—These are obtained with zinc chloride. They are not much used, but are capable of yielding fine effects. (g) Reserves under Aniline Black.—Reserves under aniline black are produced with caustic alkalis, alkaline carbonates, silicates and sulphites, sulphocyanides, oxide of zinc and the acetates of magnesia, zinc and soda. The white and coloured resists may be printed upon either the undeveloped black or upon the cloth before the black is applied. In the former case the cloth is slop-padded through a mangle-box with the following black:— . 72 lb aniline hydrochloride. 31 lb sodium chlorate. 4 lb potassium ferrocyanide-10 gals. water. It is then very carefully dried in hot air so that it becomes no darker than a pale yellow; if it is green before printing, the white is sure to be bad. The dried padded cloth is then printed with the " resist " colours, dried and steamed 3 to 4 minutes in a rapid ager, chromed through warm bichromate of potash, and finally washed and soaped. During the steaming the black is developed all over the cloth except where the colours are printed. Here its development is prevented by the alkali or the reducing agent, whichever may be present, in the colour, and instead of a plain black dyed piece a coloured design on a black Basic Colours.—The white cloth is ground is produced. The following formulae may be employed for white and coloured resists: White. 8 lb starch. 8 lb British gum. 30 lb potassium sulphite, 90° Tw. 3 gals. water. 15 lb soda acetate. lo lb bisulphite of soda, 66° Tw. lb ultramarine blue. Boil together. Print on the padded cloth, age, chrome and wash. The resist paste is as under: Resist Paste. lo lb zinc oxide. 11 gals. magnesium acetate, 400 Tw. 21 „ tragacanth mucilage (dragon). starch paste. For reducing the colours take 6 parts resist paste. 4 „ starch paste. 4. ,, white resist. Very good results can be obtained by the alternative method, i.e. printing the resists on white cloth and applying the black afterwards. The basic colours are chiefly used, though chrome yellow and ultramarine are also employed for some styles. The following formulae will serve as types of the composition of white and colours: White. 20 lb precipitated chalk. 5 lb potassium sulphite, 90° Tw. 5 Ib acetate of soda. z lb ultramarine blue for sightening. I gal. water. 6 „ starch paste. The whole ground together in a mill. Colour. {2 lb basic dye-stuff. I gal. water. 24 ,, starch paste. 17 lb zinc oxide. I gal. water. „ glycerin. turpentine. „ bisulphite of soda. L 3 „ starch paste. Print on white cloth, allow to lie a day or two, then slop-pad in the Prud homme black already given, dry, age, chrome and soap. Pigment colours may be applied on black padded cloth as follows Yellow. 40 lb chrome yellow, &c. &c. 22 gals. 40 per cent. albumen. 2 2 , tragacanth water, 6 oz. per gal. 6 lb soda ash. 1 gal. citrate of soda, 40° Tw. Other methods, varying in detail, have been used from time to time, but the above two are at the present time generally employed —especially the former, by which many fine patterns have been produced in all sorts of delicate and artistic shades. The Treatment of Cloth after Printing. After printing, the various classes of goods undergo many different treatments according to the character of the colours printed. These treatments include steaming, hanging in the ageing chamber, passing through tartar emetic, the chalk bath, washing, soaping, chemicking or clearing and finishing. (i) The operation of steaming is necessary for all styles except those with the insoluble azo-colours, vat dyes discharged, and some colours that are precipitated on the fibre. The short steaming necessary for most discharges, indigo blue prints, and aniline black is effected in the Mather and Platt ager, of which a sketch is here given (fig. 2) showing its principle.
End of Article: STYLES OF
[back]
STYLE (from Gr. a-6'1ms, a column; a different word...
[next]
STYLOBATE (Gr. rrf Xos, a column, and 00. ns, a bas...

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click and select "copy." Paste it into a website, email, or other HTML document.