Hi Madelyn!
I am a new weaver (avid knitter for 40 years) and I took a three-day course several months ago. Of course summer arrived and all my crafting went onto a back burner. I go to start and have completely forgotten how to figure out how much weaving yarn I need. The instructions that I wrote down now make no sense to me. The only part I get is that I need 10% for loom waste and something about 36" (width of my loom). Please help—I'm raring to go!!
(Actually, while I've got you could you also recommend a yarn for weaving a soft scarf with a beautiful drape?)
—Donna
Hi Donna!
Let's say you are going to weave a scarf. (The only consideration you'd be making relative to your loom's width is that you can't weave anything wider than it will allow. So your calculations will be based on the finished width of the item you want to make, and that width will have to be possible on the loom you have.)
A scarf is generally from eight to ten inches wide. Usually, you will have some draw-in as you weave (woven width is narrower than the width of the warp in the reed) and some shrinkage if the item is washed. You need to have an idea of those percentages to determine the width on the loom (draw-in and shrinkage). Let's say you choose JaggerSpun wool/silk for a soft, drapable scarf. You can use either plain weave or twill (among other structures). Let's say you sett this yarn at 30 ends per inch for a warp-emphasis plain weave or for a balanced twill. If you calculate about 15% draw-in and shrinkage you'd divide the finished width by .85. So for a finished width of about 9", you'd start with a width in the reed of 10-1/2". That would mean 10.5 x 30 = 315 warp ends.
Next, you determine your desired finished length; let's say that's about 65". I'd calculate 15% for take-up and shrinkage (that might be a little high, but it's better to figure too much than too little). So you'd need to weave 65" divided by .85 or about 76" measured on the loom. I'd therefore put on a 3-yd warp (108"), which would leave 32" for loom waste; the loom waste would include fringe. So you'd need 315 ends x 3 yd = 945 yd for the warp. If you weave 30 picks per inch at 10-1/2" weaving width, you'd weave 76" x 30 ppi x about 11" (you need to allow for extra weft for the weft angle in each shed) or about 700 yd for the weft.
The information you need to figure out the needed weaving yarn any project is: warp and weft sett, desired finished width and length, percentage of draw-in/take-up and shrinkage.
Hope this helps!
P.S. Tom Knisely has an excellent video, The Weaver's Yarn Companion, that covers choosing weaving yarn of the right fiber, weight, and type for your projects, as well as how to choose the right sett and reed for your yarn.