The Dyeing of Woollen Fabrics Part 25

acetic acid. Work at the boil for one hour; then lift, wash and dry.

_Silk, Light Sea Green; Wool, Pale Sage._--Make the dye-bath with 1/2 lb. Fast Yellow extra, 3 oz. Azo Fuchsine G, 1-1/2 oz. Fast Green bluish, and 20 lb. acetic acid. Work as in the last recipe.

_Silk, Light Green; Wool, Brown._--Make the dye-bath with 1 lb. Azo Fuchsine G, 2-1/2 lb. Fast Yellow extra, 1/2 lb. Fast Green bluish, and 20 lb. acetic acid. Work at the boil for one hour.

_Silk, Pale Blue; Wool, Crimson._--Make a dye-bath with 2 lb. (p. 196) Azo Crimson L and 20 lb. acetic acid. Work at the boil for one hour, then pa.s.s into a bran bath for half an hour at 90 F., and into another bath containing 1/2 lb. Turquoise Blue G, and 2 lb. acetic acid, at 90 F., for half an hour; then wash and dry.

_Silk, Light Drab; Wool, Lavender._--Make the first dye-bath from 3 oz. Indigotine, 2 oz. Azo Fuchsine G, and 20 lb. acetic acid. After working an hour at the boil, pa.s.s into a bran bath for half an hour, afterwards topping with 1-1/2 oz. Bismarck Brown R and 2 lb. acetic acid.

CHAPTER VII. (p. 197)

OPERATIONS FOLLOWING DYEING: WASHING, SOAPING, DRYING.

After loose wool, or woollen yarns or piece goods of every description have been dyed, before they can be sent out for sale they have to pa.s.s through various operations of a purifying character. There are some operations through which cloths pa.s.s that have as their object the imparting of a certain appearance and texture to them, these are generally known as finishing processes, of these it is not intended here to speak, but only of those which precede them but follow on the dyeing operations.

These processes are usually of a very simple character, and common to most colours which are dyed, and here will be noticed the appliances and manipulations necessary in the carrying out of these operations.

#Squeezing or Wringing.#--It is advisable when the goods are taken out of the dye-bath to squeeze or wring them according to circ.u.mstances in order to express out all surplus dye-liquor, which can be returned to the dye-bath if needful to be used again. This is an economical proceeding in many cases, especially in working with many of the old tannin materials, like sumac, divi-divi, myrobalans, and the modern direct dyes, which during the dyeing operations are not completely extracted out of the bath, or in other words the dye-bath is not exhausted of colouring matter, and therefore it can be used again for another lot of goods simply by adding fresh material to make up for that absorbed by the first lot.

Loose wool and loose cotton are somewhat difficult to deal with by (p. 198) squeezing or wringing, but the material may be pa.s.sed through a pair of squeezing rollers such as are shown in figure 24, which will be more fully dealt with later on.

#Yarns in Hanks.#--In the hand-dyeing process of hank-dyeing the hanks are wrung by placing one end of the hank on a wringing-horse placed over the dye-tub, and a dye-stick in the other end of the hank, giving two or three sharp pulls to straighten out the yarn and then twisting the stick round; the twisting of the yarns puts some pressure on the fibres thoroughly and uniformly squeezing out the surplus liquor from the yarn.

#Hank-Wringing Machines.#--Several forms of hank-wringing machines have been devised. One machine consists of a pair of discs fitted on an axle, these discs carry strong hooks on which the hanks are placed.

The operator places a hank on a pair of the hooks. The discs revolve and carry round the hank, during the revolution the hank is twisted and the surplus liquor wrung out, when the revolution of the discs carries the hank to the spot where it entered the machine, the hooks fly back to their original position, the hank unwinds, it is then removed and a new hank put in its place, and so the machine works on, hanks being put on and taken off as required. The capacity of such a machine is great and the efficiency of its working good.

Mr. S. Spencer, of Whitefield, makes a hank-wringing machine which consists of a pair of hooks placed over a vat. One of the hooks is fixed, the other is made to rotate. A hank hung between the hooks is naturally twisted and all the surplus liquor wrung out, the liquor falling into the vat.

#Roller Squeezing Machines for Yarn.#--Hanks may be pa.s.sed through a pair of indiarubber squeezing rollers which may be so arranged that they can be fixed as required on the dye-bath. Such a pair of (p. 199) rollers is a familiar article and quite of common and general use in dye-houses.

#Piece Goods.#--These are generally pa.s.sed open through a pair of squeezing rollers, which are often attached to the dye-vat in which the pieces are dyed.

[Ill.u.s.tration: Fig. 24.--Read Holliday's Yarn-squeezing Machine.]

#Read Holiday's Squeezing Machine.#--In figure 24 is shown a squeezing machine very largely employed for squeezing all kinds of piece goods after dyeing or washing. It consists of a pair of heavy rollers on which, by means of the screws shown at the top, a very considerable pressure can be brought to bear. The piece is run through the eye shown on the left, by which it is made into a rope form, then over the guiding rollers and between the squeezing rollers and into (p. 200) waggons for conveyance to other machines. This machine is effective.

Another plan on which roller, or rather in this case disc, squeezing machines are made is to make the bottom roller with a square groove in the centre, into this fits a disc, the cloth pa.s.sing between them. The top disc can, by suitable screws, be made to press upon the cloth in the groove and thus squeeze the water out of it.

WASHING.

One of the most important operations following that of dyeing is the washing with water to free the goods, whether cotton or woollen, from all traces of loose dye, acids, mordanting materials, etc., which it is not desirable should be left in, as they might interfere with the subsequent finishing operations. For this purpose a plentiful supply of good clean water is required, this should be as soft as possible, free from any suspended matter which might settle upon the dyed goods and stain or speck them.

Washing may be done by hand, as it frequently was in olden days, by simply immersing the dyed fabrics in a tub of water, shaking, then wringing out, again placing in fresh water to finish off. Or if the dye-works were on the banks of a running stream of clean water the dyed goods were simply hung in the stream to be washed in a very effectual manner.

In these days it is best to resort to washing machines adapted to deal with the various kinds of fibrous materials and fabrics, in which they can be subjected to a current of water.

#Loose Wool.#--If this has been dyed by hand then the washing may also be done in the same way by hand in a plain vat. If the dyeing has been done on a machine then the washing can be done on the same machine.

[Ill.u.s.tration: Fig. 25.--Hank-washing Machine.]

#Yarn in Hanks.#--A very common form of washing machine is shown (p. 202) in figure 25. As will be seen it consists of a wooden vat, over which are arranged a series of revolving reels on which the hanks are hung, the hanks are kept in motion through the water and so every part of the yarn is thoroughly washed. Guides keep the hanks of yarn separate and prevent any entanglement one with another. A pipe delivers constantly a current of clean water, while another pipe carries away the used water. Motion is given to the reels in this case by a donkey engine attached to the machine, but it may also be driven by a belt from the main driving shaft of the works. This machine is very effective.

[Ill.u.s.tration: Fig. 26.--Cloth-washing Machine.]

#Piece Goods.#--Piece goods are mostly washed in machines, of which two broad types may be recognised. First those where the pieces are dealt with in the form of ropes or in a twisted form, and second those where the pieces are washed while opened out full width. There are some machines in which the cloths may be treated either in the open or rope form as may be thought most desirable.

Figure 26 represents a fairly well-known machine in which the (p. 203) pieces are treated in a rope-like form. It consists of a trough in which a constant current of water is maintained; at one end of this trough is a square beating roller, at the other a wood lattice roller, above the square beater and out of the trough are a pair of rollers whose purpose is to draw the cloth through the machine and also partly to act as squeezing rollers. As will be seen the cloth is threaded in rope form spirally round the rollers, pa.s.sing in at one end and out at the other, pegs in a guide rail serving to keep the various portions separate. The square beater in its revolutions has a beating (p. 204) action on the cloth, tending to more effectual washing. The lattice roller is simply a guide roller.

[Ill.u.s.tration: Fig. 27.--Cloth-washing Machine.]

Figure 27 shows a washing machine very largely used in the wool-dyeing trade. The princ.i.p.al portion of this machine is of wood.

The internal parts consist of a large wooden bowl, or oftener, as in the machine under notice, of a pair of wooden bowls which are pressed together by springs with some small degree of force. Between these bowls the cloth is placed, more or less loosely twisted up in a rope form, and the machines are made to take four, six or eight pieces or lengths at one time, the ends of the pieces being st.i.tched together so as to make a continuous band. A pipe running along the front of the machine conveys a constant current of clean water, which is caused to impinge in the form of jets on the pieces of cloth as they run through the machine, while an overflow carries away the used water. The goods are run in this machine as long as is considered necessary for a sufficient wash, which may take half to one and a half hours.

In figure 30 is shown a machine designed to wash pieces in the broad or open state. The machine contains a large number of guide rollers built more or less open, round which the pieces are guided, the ends of the pieces being st.i.tched together, pipes carrying water are so arranged that jets of clean water impinge on and thoroughly wash cloth as it pa.s.ses through, the construction of the guide rollers facilitating the efficient washing of the goods.

SOAPING.

Sometimes yarns or cloths have to be pa.s.sed through a soap-bath after being dyed in order to brighten up the colours or develop them in some way. In the case of yarns this can be done on the reel washing (p. 205) machines such as are shown in figure 25. In the case of piece goods a continuous machine in which the washing, soaping, etc., can be carried on simultaneously is often employed. Such a machine is shown in figure 28. It consists of a number of compartments fitted with guide rollers, so that the cloth pa.s.ses up and down several times through the liquors in the compartment; between one compartment and another is placed a pair of squeezing rollers. The cloth is threaded in a continuous manner, well shown in the drawing, through the machine; in one compartment it is treated with water, in another with soap liquor, and another with water, and so on, and these machines may be made with two, three or more compartments, as may be necessary for the particular work in hand. As seen in the drawing the cloth pa.s.ses in at one end, and out at the other finished. It is usually arranged that a continuous current of the various liquors used flows through the various compartments, thus ensuring the most perfect treatment of the cloths.

[Ill.u.s.tration: Fig. 28.--Soaping and Washing Machine.]

DRYING. (p. 206)

Following on the washing comes the final operation of the dyeing process, that of drying the dyed and washed goods. Now textile fabrics of all kinds after they have pa.s.sed through dye-baths, washing machines, etc., contain a large amount of water, often exceeding in amount that of the fabric itself, and to take the goods direct from the preceding operations to the drying plant means that a considerable amount of fuel must be expended to drive off this large amount of water. It is therefore very desirable that the goods be freed from as much of this water as possible before they are sent into any drying chambers, and this may be done in three ways, by wringing, squeezing and hydro-extracting. The first two methods have already been described (pp. 198, 199) and need not again be alluded to, the last needs some account.

[Ill.u.s.tration: Fig. 29.--Hydro-extractor.]

Hydro-extractors are a most efficient means for extracting water (p. 207) out of textile fabrics. They are made in a variety of forms by several makers. Essentially they consist of a cylindrical vessel with perforated sides, so constructed that it can be revolved at a high speed. This vessel is enclosed in an outer cage. The goods are placed in the basket, as it is termed, and then this is caused to revolve; at the high speed at which it revolves centrifugal action comes into play and the water contained in the goods finds its way to the outside of the basket through the perforations and so away from the goods.

Hydro-extractors are made in a variety of sizes and forms, in some the driving gear is above, in others below the basket, in some the driving is done by belt gearing, in others a steam engine is directly connected with the basket. Figures 29 and 30 show two forms which are much in use in the textile industry. They are very efficient and extract water from textile goods more completely than any other means, as will be obvious from a study of the table below.

[Ill.u.s.tration: Fig. 30.--Hydro-extractor.]

The relative efficiency of the three systems of extracting the moisture out of textile fabrics has been investigated by Grothe, who gives in his _Appretur der Gewebe_, published in 1882, the following table showing the percentage amount of water removed in fifteen minutes:--

Yarns. Wool. Silk. Cotton. Linen. (p. 208) Wringing 445 454 453 503 Squeezing 600 714 600 736 Hydro-extracting 835 77 812 828

Pieces.

Wringing 334 445 445 546 Squeezing 640 697 722 830 Hydro-extracting 778 755 823 860

In the practical working of hydro-extractors it is of the utmost importance that the goods be carefully and regularly laid in the basket, not too much in one part and too little in another. Any unevenness in this respect at the speed at which they are driven leaves such a strain on the bearings as to seriously endanger the safety of the machine.