In twilled weaving the weft does not pass over every other warp, but over every two, every three, or even more, each weft crossing the warp at a point one thread to the right or left of the one below it. Plate 111-20 shows how this produces a series of diagonal ribs across the fabric, instead of the vertical ribs of plain weaving. The same effect can be seen in modern serge, whipcord, and some tweeds. Tweed, in fact, is only another way of saying twill. We are familiar with the same pattern in basketry, where the yucca tray (11-8) and the floor mat (11-7) were plaited (the basketry equivalent of weaving) in diagonal twill. Even yucca fibre sandals were twilled, for the method seems to have been a favorite with the Anasazi.
Plate 111-17. Hopi striped woolen blanket.
Some time before 1000 A.D. they had begun to make a twilled weave in cloth and the ruins of the famous Four Corners region abound in scraps of such material. The weavers had even gone on to variations such as the V shape and the diamond. All these are made with four sheds, as described below but the sheds pick up different warps and are used in different order.
Plate 111-18 shows the simplest form of diagonal twill, where the weft passes over two warps and under two. Looking at the warp numbers we can see that such a pattern cannot be made by opening only two sheds. There must be four, picking up the following warps.
Shed No. 1 warps 1, 2, 5, 6, 9, 10, 13, 14. Shed No. 2 warps 2, 3, 6, 7, 10, 11. Shed No. 3 warps 3, 4, 7, 8, 11, 12. Shed No. 4 warps 1, 4, 5, 8, 9, 12, 13.
After this we go back to No. 1 again and open the sheds in regular order. This pattern is generally made on a blanket loom and the sheds are opened by one stick and three heddles. The arrangement can be seen in plate 111-12 where the weaver is making the central, diagonal portion of a woman's blanket dress. His shed stick is visible near the top of the warp, with the three heddles below, one almost hidden behind the other two.
He might make the diagonal in various ways, passing the weft over three warps and under two, or over three under one; over three under three; over two under one.
Woman's dark wool blanket dress, center section. The borders were usually in some other weave.
Woman's small white cotton shawl. This was the shawl which had a red and blue borders of which the red, too, was in diagonal weave. (See plate 111-19)
Man's woolen shirts, kilts and breechcloths, usually in dark blue or black. .
Plate 111-18. Diagram of twill weave.
Plate 111-19. Maiden's red and blue bordered shawl, diagonal twill.
Plate 111-20. Fabric in a diamond twill, small diamonds.
Man's white ceremonial sash made in modern times, instead of the braided sash. (Plate 111-36)
The lines of diagonal twill can be broken and their direction changed, so that they form a series of Vs. This pattern, very frequent in tweed, is called a herringbone. The pueblos used it in prehistoric days. Their herringbones were both horizontal and vertical.
Herringbone twill, therefore, is begun exactly like diagonal, with the heddles attached in the same way. A glance at diagram 111-21 will show that the first four sheds are opened in the same order as they would be for diagonal. The change comes when the angle, or elbow of the herringbone is reached. Then the heddle order is reversed. Instead of 1234, 1234, it becomes 1234, 321, 234, 321.
Herringbone weave was used oftenest in combination with others. It can be seen in the Hopi boy's woolen blanket, in black and white plaid- Scotch plaid, we have called it. Here the warp and weft both are in wide strips of black and white. Throughout one or more weft strips the weave is herringbone, then the sheds are opened in different color, as described below, to produce diamond weave. (Plate 111-23)
Plata 111-21. Diagram of herringbone variation of twill weave.
Plate 111-22. Herringbone or V-shaped twill.
Plate 111-23. Hopi boy's blanket, the gray squares in herringbone.