Yarn Scouring.—When wool has been spnn, it comes to the manufacturer or dyer in the form of hanks, and contains in this state about 10 to 15 per cent. of rape, olive, or other oils, or oleio aoid, whioh have been added to facilitate the operations of spinning. The detergent used ia generally carbonate of soda, or a mixture of soap and soda, or of soap and ammonia, the letter for better class wools. Before scouring, it is usual with some kinds of wool, in order to prevent the felting of the yam, to steep it in hot wator for about five minutes, and then to leave it to cool. The scouring is done in large wooden boxes, heated by a perforated steam pipe. The hanks of yarn are hung on sticks placed across the box ; they are worked to and fro, and frequently turned over by two men standing on each side, for ten to fifteen minutes, then lifted, drained, transferred to a second box to be worked in a similar manner, and filially washed in cold water. The temperature of the scouring bath is about 60° to 66° (140° to 150° F.). In some establishments, the scouring of hank yarn is also done by a machine very similar to the cotton yarn washing machine, Fig. 373, p. 508. By another method, the hanks are worked about by hand in scouring liquor standing in a tmall box or tub, and are carefully placed on a travelling endless baud, which leads them through a pair of squeezing rollers, and drops them into a box behind. The process is repeated, and a wail in cold water finishes the operation. A good and rapid method of scouring woollen yarn is by means of the machine represented in Fig. 376, which is extensively used in the Paialey dye-works. A great advantage gained by employing this machine is that the scoured and dyed yarn becomes leas tangled, and will wind very much better, than when scoured by hand. It consists of two iron squeezing rollers A and B, both covered about 1 in. thick with some soft, durable material, e.g. silk noils, in order to make them elastic. These rollers are set over the delivery end of the wooden trough C, whieh is about 8 ft. long and 2 ft. wide, and is fitted up internally with wooden rollers above and below. The hanks of yarn are previously linked together, end to end, by means of a small knotted and twisted loop of cotton cord, the knot being buttoned, as it were, in the end of the twisted loop. The hanks thus form one continuous chain, and the whole operation of linking is rapidly performed by a boy. The knot is always left between the hanks, to prevent its cutting the yarn, on passing through the squeezing rollers. By this method, one man and eight boys can scour 3000 lb. yarn a day, using two machines, one for the rough, and the other for the finishing scour. By placing three machines in a row, and feeding the last one with a continuous supply of clean water, the scouring may be performed at one operation, and with fewer attendants. The advantage of this is obvious.
Yarn Sulphuring.—Yarn to be dyed in dark shades needs no further bleaching; but when certain delicate and light shades are to be subsequently dyed, or if the yarn is required white for weaving purposes, the damp scoured yarn is hung on poles, and exposed in a sulphur stove to the action of sulphurous acid gas. Finished white yarn is blued in the last washing with a little neutral indigo extract, or with a mixture of aniline blue and aniline violet, before sulphuring. The common dimensions of a sulphur stove for this purpose are :—Height of the walls without roof 12 ft.,
breadth 12 ft., length 27 ft. It is built of brick, with EL tiled floor, and is provided with a closed window at each end, and with a door, made simply but well. In the interior, there ia at each corner a furnace whereon to burn the sulphur, and opposite each furnace is au iron door opening outwards. Two of the furnaces have a small chimney 6 ft. to 8 ft. high, to facilitate the rising of the vapours to the upper parts of the stove ; the other two have none. The yarn ia hung on poles, resting on a wooden framework ; the entrance door and a trap-door under the ventilator are then closed, the necessary quantity of sulphur is placed in little cast-iron pots, lighted, and put in by the iron doors, and all is olosed up. As the oxygen in the air of the chamber becomes exhausted, the burning sulphur is extinguished. The yarn is left in from six to eight hours or overnight ; then all the doors are thrown open, and, as soon as the place is well ventilated, the yarn is taken out and hung in the open air, to allow the absorbed fumes to escape. The amount of sulphur burnt is about 6 lb. to 8 lb. sulphur to 100 lb. yarn. After sulphuring, the yarn is well washed in cold water, and dried.
Cloth Scouring.—In general, this is very similar to yarn scouring ; but, of course, the machinery is different, and there are slight variations in the time occupied and in the quantities of stuff used, according to the different qualities of the material. Fig. 377 represents one of the machines used. Four such machines, called crabbing machines, are Usually placed one behind another. Each 377.
consists of two bowls, the upper one A of iron, the lower one 13 of wood, working in a wooden box or trough C, of the following dimensions :—breadth above, 28 in.; ditto below, 21 in.; depth, 16 in.; length, 45 in. At the bottom of this box, there are a few wooden rollers, under and over which the cloth has to pass, as well as a steam pipe, for heating the scouring liquor. The bowls are arranged to be driven in either direction, in order to roll or unroll the cloth ou either bowl. The beamed pieces for scouring rest on the bracket D, and, after passing through the liquor, they are re-beamed on the loose beaming roller which rests on the inclined supports at E, and against the roller A. The pieces are singed by plate or by gas, before scouring ; they are beamed on rollers, about fifteen pieces of 36 yds. on a roller.
The following is the process for bleaching muslin-de-laine with cotton warp ; it consists of three passages through soap and soda liquors, sulphuring, mangling, and drying on steam cylinders or in the drying shed. The cotton warp threads will have been bleached before weaving, so that the present bleaching has reference only to the woollen weft. The first machine is set, when com mencing, with 2 lb. soap, and 6 lb. soda ; but generally it is set with the old sada liquor from the third machine, sometimes with half of this old soda liquor and half of the soap liquor from the second machine. The pieces run through at a temperature of 60° (140° F.). Three sets of fifteen pieces each are scoured before letting eff the liquor. The pieces are beamed on the top bowl, and the beam is transferred to the next machine.
The second machine is set for the first fifteen pieces with 1 lb. soap and 3 lb. soda. The pieces from the first machine are run into this second liquor at 71° (160° F.), and are beamed on the loose roller. To the two following sets, lb. soap is added.