use this technique in order to emphasize the contour of the object. To do it you have to entwine two warp threads (front and back) with the working thread. To make a contour we usually use thicker threads.
You can twine either one warp thread or a few of them with decorative cords. Such cords can be used for edging tapestry fragments or as separate decorative items by combining different textures and colored threads.