the.com/shantung

means A silk fabric woven with slightly irregular, nubbly threads that give it a crisp, textured surface and a characteristic sheen.

from Named after Shandong (formerly romanized 'Shantung'), the Chinese coastal province where this type of wild-silk weaving originated. The fabric was traditionally made from the silk of the Chinese Tussah moth, whose uneven, thicker fibers naturally produce that slubby, nubby texture — so the roughness isn't a design trick, it's just what wild silkworm thread does when you weave it.