The problems I'm asking about in this post relate to the part of the 2.2.3 assignment after re-threading the reed from 18 epi to 12 epi. When I tried to fix the arch appearing in the column of charcoal substitution threads, I got distortion in the existing weaving. It didn't appear immediately, though. It appeared about 2 inches into weaving at 12 epi. My working assumption is that somehow the charcoal threads lost their tension because they were tied as part of two bundles instead of all in one bundle. I've included pictures and questions are at the end of the post.
As always, any help is greatly appreciated.
1. The arch appeared after just shy of 2 inches of nice, even-fell weaving to spread the threads after going from 18epi to 12 epi. To address the arch, I tried adding more weight in back, but it made the arch more pronounced. I took the weights off, adjusted the cone-in-cone tension in the back a little to make it more consistent with the bundles on either side.
2. I noticed the charcoal substitution threads were split across 2 tie-on bundles. I decided to rearrange the tie-on bundles such that there were be three bundles tied on instead of two: a smaller white; 10 charcoal threads; and a smaller white bundle. The fell line looked better when all the substitution threads were in the same tie-on bundle presumably with the same tension. But making this change introduced distortion into the previous weaving.
3. I retied the threads to the original two bundles. The fell improved, probably because of the retying, but the distortion did not go away.across the threads felt even and I started to weave again. The distortion was still there, but eventually I got an even-ish fell. There's a funny soup bowl appearance starting about 11 shots from the top. The fell straightened out for a while - exactly 3/4 inch of weaving delight - and then started to arch up again.
Is the best practice when substituting a group of threads to tie them on as a group with no other threads in the group?
Why did the arch show up after some weaving instead of initially?
How should I have fixed it?
Once the distortion shows up, is there any way to get rid of it?