Last summer I did a blog post on how I tied on a new warp. (That post here.) I like to tie on because it lets me take advantage of a particular threading for as long as possible. Sometimes it involves a re-sleying for a different sett, or sometimes it involves a different treadle tie-up, but even with these it is a time saver.
I first learned how to tie on when I was warping front to back (f2b). When I warped f2b, my warp was tied to the back apron rod in bundles. Warping back to front (b2f) is a little different. The warp isn't cut for the back apron rod, rather the apron stick is slipped through the uncut loop at one end of the warp.
This makes tying on a little challenging. Once the weaving is cut off the loom, the remaining warp is no longer secured because it isn't tied to the apron rod. It can easily be pulled off. When I tie on a new warp, I'm careful to not pull the old warp ends off, but they do become very uneven from my pulling and tying. No matter how careful I am, I end up with uneven lengths of warp.
I was thinking about this as I finished weaving my advancing twill sample warp. My plan was to tie on a different size yarn and experiment with that. So to secure the old warp, I decided to see if I could weave in an inch or so of waste weft, close to the back apron rod to hold the warp in place.
To do this I needed tension on the warp, so I waited to cut off the woven fabric. First I pulled the lease sticks out, and then from the back of the loom, pushed the treadles down to make a tabby shed. It was pretty awkward, but I was able to weave in about four picks of a heavy yarn. I beat them down with a hair pick and then put the lease sticks back in the same way.
I found that this helped stabilize the warp quite a bit; though not enough to prevent it from being pulled out if I tugged hard enough. Even so, it helped a lot. The next time I tie on, I'll weave in a bit more and that should do the trick.