It all started when I realized I'd spun a good bit more warp than I needed for my yard of Jorvík 1307. I thought I should probably try some other weft with it so I'd have a sample for teaching aids.
I should say here that I have a good-sized collection of samples I use as visual aids when discussing various weaving concepts, structures, treatments, and colors. They're mostly offcuts from larger projects. Once in a while, though, I weave something specifically for use as a teaching sample. Jorvík 1307 was turning out to be the occasion for doing that again.
I looked through my stash of handspun worsted yarn in appropriate fibers—Icelandic, Manx Laoghtan, Shetland. I noticed I had a fairish quantity of Shetland singles yarn in the 0.6mm diameter range, some Z-spun and some S-spun. The yarn size was in the zone for Jorvík textiles, although not dead-on accurate for any of them when combined with the pre-existing 0.4mm warp. But the Z-Z versus Z-S textile divide has been on my mind since I first read Lise Bender Jørgensen's work on spin direction nearly 25 years ago. Here by happenstance I had an opportunity to experiment with it at period-correct setts using period-correct yarns. I decided I'd weave some of the warp off with each of the two types of yarns so I would have an example of two cloths sharing the same sett, with the same size and fiber type of weft yarn but differing in their direction of spin.
Partly as a relief from the attentive work I'd put into making the first part of the textile as correct as I could, I decided to beat this part of the textile by instinct, until it looked and felt "right." Purely subjective! The 17-18 picks per inch of Jorvík 1307 was too loose for this smaller weft. I didn't count my picks, but I worked hard to beat evenly, especially when it came to matching the beat I'd used in the S section when it became time to weave the Z section. Overall the weaving went speedily and without incident. I did not notice anything to differentiate the ways the two yarns behaved as weft.
It was difficult to get a good representative photo of the section woven with S-spun weft. This washed-out shot (taken on the loom) shows the texture more clearly than any of the others I took. You can make out the lozenges, but they're indistinct.
When I switched to the Z-spun weft, the structure was immediately more clear. Here's a shot taken off-loom that shows mostly the Z-spun weft area.
|Transition from S-spun weft (below) to Z-spun weft (above)|
Here's a better shot of them both together.
|Z-spun weft at top, S-spun weft at bottom|
After finishing, the S-spun section of the cloth has about 27 picks per inch, while the Z-spun section has only 25 picks per inch. I am at a loss to know whether this result stems from my having failed to beat precisely across different portions of the warp or from some property of the weft yarns themselves.
I have let some other string geeks (mostly spinners) play with the finished cloth to see what they thought. Everyone agrees that the Z-Z textile shows the weave structure most clearly. That could explain why so many broken lozenge twills are woven with Z yarns in both systems. If you're going to go to the trouble of knitting heddles for and then weaving a broken lozenge, I should think you'd want your work to be noticed!
But if that's the case, then why would Z-S broken lozenge twills even exist? The answer to that question may have something to do not with appearance, but with handling.
The Z-S textile, like the Jorvík 1307 one, gives a thick and cushy impression. Everything about it seems like it's smooshed a little more together, from the pick count to its appearance and handling. It's more limp, less dynamic than the Z-Z textile. It reminds me of a tablet-woven band with alternating threading: the twists cancel each other out, leaving the textile neutral. The Z-Z textile responds more quickly to movement, which gives it a more lively hand.
Refreshing my memory about the numbers and distributions of Z-S broken lozenge twills will be a research pleasure. Perhaps it will even lead to some practical conclusions, or at least a testable hypothesis. But for production purposes I will probably stick as much as I can to Z-Z spun twills, since I enjoy the look and dynamism of them. Also, my Z yarns are much better spun than my S yarns!