What is stretch twill fabric?
Twill is fabric that has a diagonal pattern. It is actually
woven in such a way as to create diagonal "ribs" in the fabric
itself (not just colored diagonal lines). Think of cordoroy - that
is a fabric with a vertical (up and down) pattern woven into it.
Twill is diagonal weaving. If a twill fabric has extra "give" so
that it can expand (stretch), it is a stretch twill.
Stretch twill often refers to the fabric having a small
percentage of lycra/spandex in it, usually 2-4%.