Do not use water based product to moisturized flat ironed natural hair. Early on when I had my natural hair straightened (blow out and flat iron) at the salon, I moisturized (water based product) and ruined my hairstyle.
Use coconut oil OR deep condition BEFORE you flatiron.
It was a whole new experience dealing with straightened natural hair.
I went from this:
to this by day 3 after using a water based moisturizer:
It looked like I had a silky straight half wig on top of my own curly hair.
To fix the style, I flat ironed my edges with my miniglide.
I do not recommend flat ironing dirty hair.
Results
By the way, my hair was done by Juanita of Dominican Essence salon in Brooklyn. My hair was a bit too straight so I no longer get a blowout + flat iron. I do one or the other.
This is my hair BEFORE the blowout & flat iron: