I recently cut my hair. It's to my shoulders when it's curly and is 3 inches longer than my shoulders when it's straight. I have a 3a curly type hair. I use the CHI flat iron, Tresemme Thermal Creations Heat Tamer Spray, and the Garnier Fructis Sleek & Shine Anti-Frizz Serum. No matter what I do the ends of my hair always curls up. It's fustrating to spend all that time straightening my hair when it doesn't stay straight. I understand that it's going to curl a bit when it's humid outside, but it still curls up when it's not that humid! How do I get it to stay straight?