Carpets

by R. S. Brinton

Fig. 17
PRINTING DRUM, COVERED WITH YARN, PARTLY COLOURED

The actual printing or painting of the yarn is effected by means of the scroll pulley, which revolves in a box The arrows show where the repeats begin containing the colour, the whole being borne by a carriage running on rails across the width of the drum at the bottom of the frame. The colours are made up by an expert colourist to match the required shades, and by the admixture of flour and water are brought to the necessary consistency, which is about that of a thin paste, so that the colouring matter is dense enough to adhere, but liquid enough to penetrate the yarn fibres. In the carriage, the colour roller, which revolves in the colour, is supported by springs which tend to give it elasticity and keep it up against the face of the drum. The carriage is drawn across the drum by a rope which is mechanically actuated, and, of course, harmonises with the revolution of the drum. At the end of each traverse of the colour carriage there is a pause, which gives the printer time to change the pawl into the new tooth of the index at which it is required.

The printer is guided in his selection of colours for each scroll that he prints by the “scale board” and the “design board.”

Scale boards vary according to the pitch of the design paper, and according to the length of the design, and the number of times in which a design repeats in one revolution of the printing drum. Thus, for a design on squared paper running seven per inch in its length, the scale board is marked into divisions of seven to the inch throughout its length, so as to correspond with the horizontal divisions on the design paper. Supposing a design repeats four times in the whole revolution, a quarter board is employed; if it repeats twice a half board, the total number of scrolls being divided into four or two respectively. Thus, if the size of the drum is 648 scrolls and the number of wires in one repeat of the pattern is 162, the quarter board will have four vertical columns of figures, running respectively 1-162, 163-324, 325-486, and 487-648. The scale board has a bevel edge, and is preferably arranged so that it can be moved over the design board and aligned with the vertical line of the design which the printer is reproducing.

Fig. 18
SCALE AND DESIGN BOARD COMBINED

Fig. 18 represents part of a scale and design board combined. The numbers along the top indicate the threads in the design, and the printer may be supposed to be ready to print the eighth thread. The numbers on the right-hand side represent the wires in the carpet, with which the numbers on the scale board and the scrolls in printing correspond. The design is 216 wires long; and as the number of scrolls the drum will take is 648, the design is repeated three times in one revolution. The scale board is numbered in three columns; and for the first, second, and third repeats of the design, the printer uses the first, second, and third divisions on his scale.

To minimise the danger of bad effects from a colour running, the rule is to begin printing with the lightest shade. In this instance, the lightest colour is yellow, represented (heraldically) by spots, and it occurs first at the fourth horizontal line. The printer, therefore, turns the drum by hand, and puts the pawl in tooth number 4. He then puts the mechanism in gear and prints the scroll in the manner described, following on immediately by printing a second scroll at number 5. He then reads further down the eighth vertical line of the design, and sees that the colour recurs at 10, 11, 18, 19, 24, and 25. He therefore puts the pawl in the corresponding teeth of the index consecutively and prints accordingly. When all the yellow squares corresponding to the first column of the scale board have been read, he will take the second column, and print 220, 221, 226, 227, 234, 235, 240, 241 and so on, and then those in the third column. The remaining colours will then follow on in order of their delicacy.

When the printing of a drum has been completed, the next process is scraping. The scroll pulley in the act of printing always conveys more pigment on to the yarn than is needed to colour it, a little wall of material being left on each side of the path of the roller. This has to be removed, or it would smudge. This is done by means of small vulcanite tools, bevelled to a blunt edge, from ½ in. to 2 in. wide, the operator being aided by a steel bar fixed across the face of the drum as a guide. Scraping has, however, a further purpose beyond the removal of superfluous colour, and one no less important; for by skilful pressure and rubbing, the colour is caused to penetrate more deeply into the yarn.