No offense to your childhood hairdresser, but he's making excuses. Of course heat protectants are not going to shield your hair from all heat. If they did, then nobody would use them, because the hair would never get straight. As he said, the iron is hot, touching your hair, there's no getting around that. But the way that I understand it, the cones in heat protectants wrap around your hair and form a protective barrier, so even though you aren't protected from all the damage that heat can do, it does take "the edge" off.
And with the example of your finger...I think it's a little faulty, just because of the inherent differences between the living tissues of the skin and the dead material that is hair. Heat protectant works for the hair the same way that like..cloth works for skin. If you go outside on a really cold day with a sweater, you're still going to feel the cold. But it's better than going out there butt naked, because at least you're getting some kind of protection. Imo, any protection is better than none.
And lastly, I think if anyone doubts that they actually work, then they should try straightening once a week with heat protectant for a month, and then straightening the same amount, the same time, but without heat protection. I bet they won't make it that full second month.
