Blossom's hairdresser doesn't appear to be completely wrong, I think it's maybe been misinterpreted somewhere (not by Blossom) and this review says:-
[QUOTEGHD stylers seal in your hair’s natural oils, moisture and color.]
From this review:-
http://www.behindthescenesmakeup.com/reviews/review-ghd-hair-straightener/
Yes it's very old, but I know I'd heard something similar which is why I went hunting for it. I use GHD's everyday on short (inverted bob), fine, thin hair and don't have any problems with split ends, burning or anything. I also wash, condition and blow-dry it everyday without any problems. I think it's because I don't use any products that my hair is OK, my friend who religiously uses heat protection has this weird, dull, heavy look to her hair and envies my swishy bob
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What you've got to remember is that everyones hair is different. I have clients who get cuts once a year and don't get any split ends, whereas i'll cut my sisters and she'll straighten it once causing split ends to the point it needs cutting again.
Some peoples hair is just more prone to split ends and to prevent that you need products. Products will not 'cause' split ends.
Some peoples hair is also naturally dryer than others, usually coarser hair types, whereas finer hair is much more shiny and smooth due to more moisture, and so your 'swishy' hair
@Trinity [emoji12] but thats not to say fine hair isn't going to get split ends because not everyone with fine hair has a lot of moisture in it, hence blossom's fine hair with split ends. I find you're at one end of the scale or the other.
Blossom please use the hear protection spray, you'll do more bad than good not to.
As for a straightening iron sealing in natural oils, yes they do... Natural oils generally don't reach the ends of your hair otherwise it'd be oil from root to tip when it hasn't been washed. But putting the straighteners on too high a hear would cause any products or oils on the hair to evaporate.