The common construction of the heckle is the following: (see [fig. 424.]) [Fig. 424.] is the ground plan, and [fig. 425.] is the section. Upon an oblong plank a b, two circular or square blocks of wood c and d are fixed, in which the heckle teeth stand upright. To give these a firmer hold they are stuck into holes in a brass or iron plate, with which the upper surface of c and d is covered. Both heckles may be either associated upon one board or separated; and of different finenesses; that is, the teeth of the one may be thinner, and stand closer together; because the complete preparation of the flax requires for its proper treatment, a two-fold heckling; one upon the coarse, and one upon the fine heckle; nay, sometimes 3 or 4 heckles are employed of progressive fineness. The heckle teeth are usually made of iron, occasionally of steel, and from 1 to 2 inches long. Their points must be very sharp and smooth, all at an equal level, and must all graduate very evenly into a cylindrical stem, like that of a sewing needle, without any irregularity. The face of the heckle block must be uniformly beset with teeth, which is done by different arrangements, some persons setting them in a circle, and others in parallel rows; the former being practised in Germany, the latter in England. The coarse heckle is furnished with teeth about one tenth of an inch thick, one and a quarter of an inch long, and tapering from the middle into a very fine point. In the centre of the circular heckle is a tooth planted; the rest are regularly set in 12 similar concentric circles, of which the outermost is 53⁄4 inches in diameter. The fine heckles contain no fewer than 1109 teeth. Instead of making the points of the teeth round, it is better to make them quadrangular, in a rhombus form, in which case the edges serve to separate or dissect the fibres.
The operation of heckling is simple in principle, although it requires much experience to acquire dexterity. The operative seizes a flock of flax by the middle with the right hand, throws it upon the points of the coarse heckle, and draws it towards him, while he holds the left hand upon the other side of the heckle, in order to spread the flax, and to prevent it from sinking too deeply among the teeth. From time to time the short fibres or tow sticking to the teeth are removed. Whenever one half of the length of the strake of flax is heckled, it is turned round to heckle the other half. This process is repeated upon the fine heckle. From 100 pounds of well-cleaned flax, about 45 or 50 pounds of heckled flax may be obtained by the hand labour of 50 hours; the rest being tow, with a small waste in boony particles and dust. The process is continued, till by careful handling little more tow is formed.
Many contrivances have been made to heckle by machinery, but it may be doubted whether any of them as yet make such good work with so little loss as hand labour. In heckling by the hand, the operative feels at once the degree of resistance, and can accommodate the traction to it, or throw the flax more or less deep among the teeth, according to circumstances, and draw it with suitable force and velocity. To aid the heckle in splitting the filaments, three methods have been had recourse to; beating, brushing, and boiling with soap-water, or an alkaline lye.
Beating flax either after it is completely heckled, or between the first and second heckling, is practised in Bohemia and Silesia. Each heckled tress of flax is folded in the middle, twisted once round, its ends being wound about with flaxen threads; and this head, as it is called, is then beat by a wooden mallet upon a block, and repeatedly turned round till it has become hot. It is next loosened out, and rubbed well between the hands. The brushing is no less a very proper operation for parting the flax into fine filaments, softening and strengthening it without risk of tearing the fibres. This process requires in tools, merely a stiff brush made of swines’ bristles, and a smooth board, 3 feet long and one foot broad, in which a wooden pin is made fast. The end of the flax is twisted two or three times round this pin to hold it, and then brushed through its whole length. Well heckled flax suffers no loss in this operation; unheckled, only a little tow; which is of no consequence, as the waste is thereby diminished in the following process. A cylindrical brush turned by machinery might be employed here to advantage.
The boiling of flax with potash lye alone, or with lye and soap, dissolves that portion of the glutinous cement which had resisted the retting, completes the separation of the fibres, and is therefore a good practical means of improving flax. When it is performed upon the heckled fibres, a supplementary brushing is requisite to free it from the dust, soapy particles, &c.
Can flax be prepared without retting?—The waste of time and labour in the steeping of flax; the dyeing of the fibres consequent thereon, which must be undone by bleaching; the danger of injuring the staple by the action of putrescent water; and, lastly, the diminished value of flax which is much water-retted, are all circumstances which have of late years suggested the propriety of superseding that process entirely by mechanical operations. It was long hoped, that by the employment of breaking machines, the flax merely dried could be freed from its woody particles, while the textile filaments might be sufficiently separated by a subsequent heckling. Experience has, however, proved the contrary. The machines, which consisted for the most part of fluted rollers of iron or wood, though expensive, might have been expected to separate the ligneous matter from the fibres; but, in the further working of the flax no advantage was gained over the water-retting process.
1. Unretted flax requires a considerably longer time for breaking than retted, under the employment of the same manipulations.