Crimp

What crimp does to a design

Crimp is the waviness a yarn takes as it bends over the crossing threads: crimp % = (straightened length − cloth length) ÷ cloth length. It decides how much yarn a design consumes, how thick and how extensible the cloth is, and how dense it can be set. In a jammed plain weave of equal yarns the crimp is 20.9% in both directions; a 2/2 twill needs only 13.1%; a warp rib may take 57% in the warp and none in the weft.

Open Weaving Calculations 15–16 for the full derivation and the live calculator (θ, spacing, cover factor and crimp for any pair of diameters).