Looking for linen thread for weaving, I stumbled back to the same store that offered the Overhogdal Tapestry book. I decided this was fate and got a copy. Most of the pages are dedicated to possible interpretations of the images and the story of the tapestry's discovery. But there is good information on how it was made. And great pictures! By a close inspection of the images, I found at least two ways the soumak is worked. If, as you go from right to left and back again, you wrap your snare so the wrap-back is on top of the prior stitch, you will get V-like rows that look a bit like knitting or tablet-weaving. But if you go over as you work in one direction, and then under as you go in the other, you get a twill effect. Hard to explain in words, a picture would be better. You'd see the same thing if you worked stem stitch back and forth, which this is largely similar to.
I tested both techniques on my tapestry sampler, which hasn't been touched since... was it Battle on the Bay? I think I understand them. I am trying to decide if I am pulling the tapestry off the loom so I can weave a seat cover for Pentathalon.
In other string news, I am seriously doubting my ability to finish the socks in a month. I thought my hand was fully healed, but just 1-2 hours of work over the weekend seems to have put it on a bad path again. Not going to mess with it.
But! I've also found a reasonably-priced source of sand casting material, so a pewter seal is back on the table as a possibility.