Well, this is something I would never have thought of. While searching for assistance in determining the basic dimensions of a toe-up sock (so that I could knit it with the size needles and type of yarn I wanted without having to change to match the pattern), I came across an awesome “Super Sock Calculator” by a Danish knitter named Eddie. However, one of her top blog posts included basic instructions on how to reuse the yarn in machine-knit (i.e., store-bought) sweaters. She references Kristin Roach’s, Lee Meredith’s, and Dawn’s blog posts describing in step-by-step fashion how to do this.
If you’re genuinely interested in how to recycle sweaters for the yarn, I’ll let you read the blog posts yourself. But basically, it is possible to literally unravel the entire sweater and ball up the yarn for later use. Eddie gives as an example a wool and nylon (perfect for sock yarn) sweater in a color she absolutely loved, but goes on to say that she has also repurposed cotton sweaters, among other fibers. The caveat is that the yarn you unravel from a machine-knit sweater is often so thin that you have to ply (i.e., twist) the yarn yourself in order to make it thick enough to actually knit with it.
What’s amazing to me is the thought that you could basically get almost-free yarn for life if you’re willing to go to the trouble of unraveling it all. For example, clothing sells very horribly at garage sales, so if you wait toward the end of the sale, people will often be willing to practically give away whatever clothes they have. Why not go to a garage sale, check for any decent-quality sweaters in likable colors with favorable seams, and essentially come away with several balls of yarn for $0.25?
Of course, I’m told there’s a limit to one’s frugality. 🙂