it's true you cant sew it to strechy material ( unless you leave alot of slack in the thread. but if you hot glue the bundles the fabric will still stretch.
hummm.. i did the same thing but with a curling iron (don't have a straighter) but i didn't do the brush thing.. i by hand unwrapped the yarn i might have to do the brush next time
The only time I've had this happen to me is when i've tried to use cotton. It just fell apart.
You have to use a high quality acrylic yarn or wool works well for a more natural texture.
I'm using Lion Brand right now, and I finally got it to work, although it's fragile and falls apart easily.