All yarns are initially spun as single plies. In the ancient Peruvian
textiles, there are evidences of preferences for single-ply yarns or
at least the use of them even in fabrics we should consider called for
heavier elements. The Chincha domestic cloths are good examples. We
made yarn analyses on half of the total number of cloths in the study.
All but ten of the fifty-seven examined were woven with single-ply
warp and weft elements and of these ten, only one coarse cloth had
2-ply warps and wefts; the remaining nine had 2-ply warps crossed by
single-ply wefts. The majority of these fabrics classified as "fine"
weavings.
Yarns may be twisted (spun) in two directions. The spirals formed by
twisting may extend upward to the left (the S-twist) or to the right
(the Z-twist). The frequencies of the left and the right twist in
yarns are indicative of motor habits, if nothing more.
The largest Chincha group comprises twenty-nine cloths in which the
warp and weft elements have left spirals; a much smaller group (5
specimens) shows yarns with right spirals. Two other groups (6 and 3
pieces, respectively) have warps with left spirals crossed by wefts
with right spirals and vice versa. The other cloths in which yarns
with different twists are combined perhaps may represent the use of
odds and ends of yarns. The following combinations were found:
1. Single-ply S-twist and Z-twist warps crossed by single-ply S-twist
wefts (2 specimens) or crossed by single-ply Z-twist wefts (1
specimen).
2. Single-ply S-twist warps crossed by single-ply S-twist and Z-twist
wefts (1 fine-texture specimen).
Yarns are characterized as soft- or slack-twist, medium-twist, hard- or
tight-twist, with various intermediate degrees depending upon the
angle taken by the spiral in relation to a vertical axis. A 25-degree
angle, for example, characterizes a medium-twist yarn tending toward
hard-twist. Yarns with 30-degree to 45-degree angles of twist are
hard-twist yarns. More than half of an unselected sample of twenty
yarns fell within the 25-degree to 45-degree range. The remaining
seven had angles from 50 degrees to 90 degrees in some sections of
their lengths. An idea of the variations in any one weaving element
may be gained from plate 4,c and the enlarged section of fabric in
plate 7,c.