I recently had a friend blow dry and flat iron my hair. She used Nexxus Heat Protectant - it came in a spray bottle. I did not feel like I had anything on my hair. I like it very much. It did the job with no buildup or residue. It is a little pricey, but if you blow dry and/or flat iron often it is worth the price. Especially, becase I do not believe you need to use an excessive amount of the product.
There are pictures in my photo albulm of the blow dry and flat iron.
I guess I should mention that I believe I am a 3C when it comes to hair.