I looooove my ceramic hair straightener -- on both mine and my doll's hair! It has worked wonders, believe me. Those are good to use on doll hair, but you can also use ceramic curling irons. You can buy them at places like Ulta, Sally Beauty Supply, etc. That way you can curl your doll's hair but protect it from heat damage. I have one of each, and it helps protect your hair ( and your doll's hair!) really well.

But BE AWARE: not all ceramic straighteners are REAL ceramic! So-called ceramic straighteners that cost under about $60 are NOT true ceramic straighteners. They are ceramic-coated metal straighteners, and when the ceramic flakes off, the metal is exposed and can really mess up your hair. So be careful when using the cheaper straighteners; while they do work, as they age that ceramic coating will strip off. The same applies to ceramic curling irons. Real ceramic (read: actually made of ceramic tiles) cost around $80-$200 and often include tourmaline or sapphire in them to help with frizzies and protection from the heat and will actually shatter if dropped hard enough. Name brands of "true" ceramic straighteners or curling irons include Rusk, Wigo, Chi and FHI. Just an FYI!