I found some more yarn for sock knitting...in an old wool blanket. This blanket came from a rummage sale about ten years ago, cost $2, and actually was only the top half of a blanket.
Before I deconstruct anything vintage, I do a gut check and ask myself if I am doing the right thing. In this case, the answer was yes; I had owned the blanket for about ten years, but I never really used it, although I liked it a lot.
Not every wool blanket can be unraveled; almost all are too fuzzy or too felted. But it worked very well with this particular blanket. The only obstacle was that I had to trim back the warp threads (the ones that run lengthwise) every quarter-inch, otherwise the weft thread was too difficult to pull out. So I could glean at most half of the wool in the blanket. (The rest could have been saved for stuffing something, but I didn't.) The fringe in the photo is the warp threads ready to be trimmed.
For this blanket, I found that there were two weft (crosswise) strands; the weaver must have used two shuttles, throwing one across and back, and then the other one, crossing strands at the edge. Understanding this helped me to unravel longer strands of wool from the blanket. I unraveled as much as I could of each strand, and when it broke (where the edges of the blanket were worn) I wound the strand up into a little ball.
The unraveled strands were kinked, but I used them as they were. The "hand" (yarn texture) felt a bit crisp, but not scratchy. I found that three strands used together knitted up well with the size of needles that I have.
I unraveled just enough to knit up another pair of socks, of the same pattern as before. I still have more than half of the half-blanket left.