Not all naturals can flat iron their hair. This is a fact. The last time I flat ironed my hair, it was over 2 years ago. It was my "present" for reaching bra strap length. I washed my hair, stretched it with curlformers, applied my heat protectant, and flat ironed my hair on 200 degrees Fahrenheit. The result...severe heat damage. A few days after I flat ironed, I noticed 1 to 2 inch split ends going all the way up my hair. They were everywhere. Despite all of the prevention and protection I took to prevent heat damage, I still got it and there was no fixing it. I knew what I had to do. I spent most of that year trimming away the damage. It took me an entire year to reach waist length when it would've taken me only 9 months. I learned a valuable lesson that year. I cannot flat iron my natural hair, like forever. And I'm ok with that. It means that my hair can be healthy, and I can retain length. The healthy hair is much more important.
Of course, as I mentioned before, I love wearing my hair stretched and showing length. So if I wanted to get my hair somewhat straight with no heat, then I would have to think outside of the box. The result was a year worth of testing and thinking about ways to straighten my hair with absolutely no heat. This involved an email to curlformers to make straigthformers (they said they couldn't...be they are actually working on it) and an idea similar to the most recent failed attempted at CWK plates (I didn't have the desire to make more than a days worth of effort). Eventually, I figured it out. Take an old stretched hair style like a roller set, perm rod set, even a braid out, and low bun over night. The result is super stretched hair that gets almost fully straight. So, there it is. You can straighten your natural hair without heat.