The hair used on reborn babies is called "mohair" and comes from Angora Goats. This is the most important part of the baby, as using the wrong, or poor quality hair, can ruin the realism of the doll. After buying high dollar mohair, and being dissappointed in the quality, I decided to raise my own Angora Goats. I feed them high quality show goat food that enhances the fiber/hair and makes it shiny and healthy. I process my own hair , which is very labor intensive, but is well worth the time and effort.
When rooting the hair, I use a 42 guage German Forked rooting needle. It allows a true "micro-rooting" as it only allows one to two hairs to root into each follicle, thus preventing plugs. It is time consuming, but well worth the results. I match the baby's eyebrows to the hair color. There is nothing worse, in my opinion to see a baby with light brown eyebrows and dark brown hair!
The recent trend, is to paint the scalp, under the rooting. I, sometimes paint the whole head, and sometimes, just the hairline--to give the baby that subtle newborn peach fuzz look. The handpainting is done with a very fine paint brush and each "hair" painted, tediously, stroke by stroke. Each layer has to be baked, in between, so this process is more time consuming, to me, than the micro-rooting.