In an earlier post, I had made a passing comment that my left selvedge was creating more problems than the right selvedge. I didn't pay this too much mind as my understanding is that for most people, one selvedge is not as good as the other. A solution commonly offered has been to change seating positions. I have hesitated to try that as moving away from center would affect the evenness of my beat.
This morning, the left selvedge was becoming progressively worse. I did some feeling around with my fingers/hands, testing for tension. I couldn't quite tell, but it seemed like the threads on the left side might be just a tad looser than the others. So I got out a wooden double-pointed knitting needle (size 7), and inserted it between the back beam and the first 5 threads on the left selvedge. The selvedge immediately improved. The left and the right selvedges looked virtually identical.
Yes, this is magic, but not without its own problems. As I continue to weave, the added tension to those 5 threads will result in those threads gradually stretching and getting looser and looser. Another knitting needle will have to be added. And later, I will probably have to hang weights from those knitting needles. Except in this case I will probably not have to do the last as I have only about 12 more inches to weave off.
And what effect will this gradual stretching of those 6 warp threads have on the appearance of the finished weaving? I don't know. I expect that in this case, with washing and hard-pressing (or, in this case "killing", for I am working with acrylic yarns) there will be no discernible difference. Perhaps it might affect the wear and tear on that side? I don't know, but if one wove for a long time with these few threads specially weighted and growing more and more stretched out, I wouldn't be surprised.
In any case, this "magic" solution is only for emergencies. The real issue is that I muse figure out how to keep this from happening on future warps.
I do have a suspicion, and therefore a solution for, of what may be happening. I attach my warp to the front beam by lashing with very slippery mason cord. I lash from left to right. To begin, I attach the cord with several knots on the left side. My suspicion is that there is some slipping on those knots. I do have a book of knots and I might investigate that for solutions. But I think I will also use a separate, non-slippery cord, to tie the warp rod to the apron rod. There should be much less tendency for the knot in this cord to slip, We shall see.