First part of a serial article on leno (gauze) weaving from The Melliand, explaining how warp threads cross one another and how steel doups are used to produce the crossing. It describes the plain steel doup and the slotted (super) doup, with a marquisette loom attachment, a dobby head with jumper motion, and drawing-in and chain drafts. Examples include marquisette, warp stripe, checked and filling-border leno, and a leno and figured rib curtain fabric. The article ends 'To be continued'.