Tsumugi is an obsolete, costly, narrow Japanese silk fabric made in the following fashion: first, a coarse cloth is woven with cotton wrap and thick silk filling; second, this fabric is run through a dye vat several times; third, it is buried in the ground until the cotton warp has rotted; lastly, the silk is rewoven into a fabric. The result is a mottled design produced by undyed places in the silk yarn where the cotton warp prevented dye penetration.

Olympus Company of Japan developed a cotton fabric similar to the true Tsumugi.