Known as shirring. Having said that, the glance it produces is similar to smocking, that's an embroidery technique that’s been around an extended long time. But maybe don’t google “what's smocking” cuz evidently In addition, it refers to something which has practically nothing to accomplish with sewing… Anyway, shirring Durability: https://covered-elastic-yarn65420.educationalimpactblog.com/53741382/not-known-facts-about-double-covered-yarn