How To Add Volume To Your Flat Ironed Hair – How To Get Thick Flat Ironed Hair. When a women flat irons her hair, she doesn’t want to have thin flat pieces. We all desire to have thick and voluminous hair even though it’s straight. Over the Thanksgiving break I decided to flat iron my own hair. I first braided my hair in 6-8 box braids, and let it air dry over night. The next day I placed my usual heat protect on my hair and proceeded to flat iron. I didn’t even have to blow dry my hair, which meant less heat. The end result was a thick luscious look that I loved. See my video below for more details, and don’t forget to subscribe to my youtube channel for more hair tips and advice.