Subsituting 8/2 Tencel for 10/2
I am planning a project from Handwoven's Design Collection 19. Instead of the 10/2 Tencel specified, I ordered 8/2. Can I use this in place of the 10/2 and should I change the sett from 2 per dent in 12- dent reed to another reed or sleying order? I am a new weaver.
Both Tencel and pearl cotton are available (in a multitude of colors) in the 8/2 size (3,360 yd/lb) and the 10/2 size (4,200 yd/lb). If you check the Master Yarn Chart, you'll see that the balanced plain-weave sett for both 10/2 pearl cotton and 10/2 Tencel is 24 ends per inch, the sett for 8/2 pearl cotton and 8/2 Tencel is 20 ends per inch. For any project requiring a balanced plain weave, sley 2/dent in a 12-dent reed to achieve 24 ends per inch and 2/dent in a 10-dent reed for 20 ends per inch. You'll have to change the number of total warp if you want to achieve the same warp width if you substitute one for the other.
If you are weaving twill, however, the appropriate sett for either yarn is harder to determine and depends on the length of the floats in the twill (the longer the floats the closer the sett). Twills are additionally tricky in that reed measurements with these yarns usually force an irregular sleying. Your project is probably the Peacock Shawl, pages 28–29, in Design Collection 19, Scarves and Shawls for All Seasons. That draft has very short floats in twill squares separated by sections of plain weave. For that reason, even though it includes twill, the sett chosen by the designer is the same as for a balanced plain weave. In looking at the photo of the shawl, however, I see that the design is not quite woven to square; that is, the squares of twill are actually shorter than they are wide. You might consider a sett of 25 ends per inch instead of 24. In that case, you'll have to use an irregular denting order (I'd probably go for 2-3 in a 10-dent reed as the best way to distribute the threads evenly.
I hope this helps!
P.S. Note that in last week's Ask Madelyn (reprinted from January 11, 2012), I used faulty math in calling 3/dent in a 12- dent reed equal to 32 ends per inch. Well, that would clearly produce 36 ends per inch. To get 32 in a 12, you'd have to sley 2-3-3 in a 12-dent reed. Thank you careful readers!