How Hot is Too Hot for Healthy Hair?
I like to use a blow-dryer with a diffuser attachment on my hair after I have put hair gel in it for about 5 minutes. The heat and quicker-than-air-drying treatment “sets” the waves and curls in my fine hair. Then I let it air-dry until dry. If I let it air-dry exclusively, the weight of the water tends to lengthen the curls and waves somewhat. I worried that the heat would be damaging to my hair – so a little testing and research were in order. ©Science-y Hair Blog 2013 I put a thermometer’s sensor in the bowl of the diffuser right where I put my hair. The hair dryer was set on "warm" and "low." The temperature rose to 125°F (52°C). Now, looking at an article published in the Journal of Cosmetic Science titled, "The Cracking of Human Hair Cuticles by Cyclical Thermal Stresses," I have some answers. The author tested hair alternately immersed in water, then blow dried at various temperatures from 86° to 212° F (30°C to 100° C), re-wetted, and blow dri...