Silver
Member
My belief based on my hair (4ab natural) is that intense heat DC over time does infuse the hair with moisturizing properties thereby making it heavier, ergo, looser pattern. I don't have damaged hair. I have been sitting under a hot dryer, weekly for as long back as almost a year. My cuticles do not show damage. In the last couple of months I have started to DC for 2 hours a week and boy is my hair different in a even better way. My hair loves heat/dc combo.
As far as flat ironing is concerned, I do think that when I flat iron my intensily moisturized hair it pushes that moisture further into the hair cuticle, again making it looser even when wet. I do not flat iron often at all.
I also am a big fan of washing with baking soda and have found that it too loosens and softens hair.
I'm going to attach an article web link that does back up what you're saying with the heat and conditioner stuff. Also deep conditioning my hair has improved my texture/curl. But flat ironing the hair or blow drying all the time will damage hair. I'm not against heat at all, I don't wear my hair curly, so I use it. I do not think heat is bad, because I'm a guilty user of flatirons and hand held blow dryers. To the OP just make sure you recognize the signs of damage if they come, I hope your hair does well like your sister's , heat works for some people.
http://thebeautybrains.com/2008/04/29/how-to-protect-your-hair-from-heat-damage/