It turns out that transforming straight limp pieces of yarn into cute, perfect little boingable curls for dolls, is incredibly simple.
Wrap the yarn tightly around a knitting needle. I used a standard, Red Heart, worsted weight yarn. The size and thickness of the needle will depend on the size of the doll for which you're making the hair. For our tiny sock dolls, I wrapped the yarn around wooden kitchen skewers. Tie the yarn tightly at the ends - I started out with a slip knot, and ended off by casting on a stitch, as for knitting.
Wet the yarn on the needles. I used boiling water from an instant hot water tap, but because heat will be applied in the next step, I don't think the temperature of the water matters.
Place the wet, yarn covered needles, or skewers on a cookie sheet, and put them in the oven at 200 degrees Fahrenheit. I put mine into a cold oven let it preheat while they were in. That took three minutes. Then, I turned the oven off, and left them in for an additional three minutes. Keep a close on the yarn in the oven, you wouldn't want to catch your oven on fire, just for the sake of doll's hair.
After the yarn cools, remove it from the needles, either sliding it off the end, or unwinding it, and cut it to the the desired lengths.
For the yarn dolls, I tied four, or five curls together, and sewed them on to the dolls head with the lose ends of the yarn that I had tied them together with. It took two to three clusters of curls per doll, which was about four skewers worth of curled yarn. To finish off the dolls hair, I trimmed the front curls short, for bangs.
For the yarn aliens, I used four shorter curls, tied together, and sewed to the center top of the dolls' heads. I also gave them plastic bubble helmets for space travel (we wouldn't want any one's eyes getting sucked out by the atmosphere of alien planets), but I'll tell you more about that in another post.
It's great to be a homeschooler.