About a year ago I got into the habit of occasionally buying a three-dollar sweater at a thrift store, and turning it into thirty-dollars-worth of wool yarn. It's a pretty fun process, and while time-intensive, it's one of those things you can do while watching back-episodes of your favorite TV show on Netflix.
Here's a batch of nice chunky green yarn :
And the sweater it came from (cute as is, but not my size!):
There are a few simple tips that make the process easy enough to be actually worth it, and without which you can end up with a tangled mess on your hands. First, you need a sweater that was knitted in individual panels, not assembled from machine-knit yardage that was cut and sewn together. Here's what my sweater looked like when I separated the panels:
Each of these individually-knit panels will unravel into a nice long continuous strand of yarn. Had the panels been cut instead, all their edges would be ragged loose ends, and they would unravel into a bunch of uselessly short pieces. You can tell the difference in the sweaters while you're shopping by looking at the seams. Here's some great pictures of "good" seams vs. "bad" seams. For the methodology of separating the panels, I like these two tutorials better. The key is to find the chain of crochet stitches that make the seam, clip it in the right place, and undo the seam just by pulling on the loose end. If you don't get this part down, and you find yourself trying to separate the panels stitch by stitch, you'll probably accidentally cut the yarn you're trying to salvage, and the process will take WAY too long to be worth the effort. If you do it right, the seam unzips almost like the top of a dog food bag. (More nice pics of that important crochet chain here.)
I unravel my sweaters directly into balls using a ball-winder so that it never gets the chance to tangle. If I feel like cheating I stop there, and just use those balls of yarn for my next project. But if I'm being good, I then unwind it into hanks, straighten it, and re-wind it... Yarn that's been unraveled tends to retain the kinks from the knitting. Some people say this makes their project come out uneven. But the straightening process (which would require another post to explain) takes at least as long as the unraveling, and in my opinion, the time investment diminishes your return. If you're planning on selling the reclaimed yarn, you should probably straighten it, or include a disclaimer. Knitting issues aside, you can't measure the length accurately when it's kinked. (Measuring the length will also be the subject of another post. I came up with a kind of cool way to do it without some of the expensive gadgetry, and I'll put together some video I took of it, so stay tuned!)