S twist
noun
a direction of the twist in yarns, from top left to bottom right, resembling the long stroke of the letter S.
Compare Z twist.
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020
Examples from the Web for s twist
The spirals formed by twisting may extend upward to the left (the S-twist) or to the right (the Z-twist).
Chincha Plain-weave cloths|Lila M. O'Neale