Sprang sashes are very elastic. How to finish off an elastic cloth can present a challenge. Historic military sprang sashes are gathered together before the fringe. This is the only point in the sash to have a weft. I reserved some of the same thread when I set up the warp. Several lengths of this reserved thread are used together for this weft. Actually two weft thread bunches are required, one for each end of the sash.
The weft thread bunch is placed in a completed row. Another weft bunch is placed in the mirror-image row. These weft thread bunches criss cross in subsequent rows. I placed little yellow or green loops to help me later to snug up these wefts. I use spring-loaded clips to keep the weft threads and the little green or yellow loops out of my way while weaving.
Gathering happens after the weaving is complete. Bunching the threads up during the weaving invites those tangle pixies and results in a less-than-perfectly-even fringe head. I wait until after the weaving is complete, and the circular warp cut apart before I tighten up the fringe head. Knots that I made when setting up the warp were lined up. I am glad to report that I am cutting very near that line of knots. The knots will not be part of the finished sash.
All that is left is the fringe twisting.
That’s my little exercise weight. Hours and hours of weaving, I find the weight useful for wrist and forearm exercises, prevents problems. The weight also keeps the sash in place, provides counter-tension for the fringe twisting. In this picture you will also notice that those little yellow threads are now snug against the fringe head. I incorporate the weft bunch into the fringes.