Mik says…I found a new study made in Korea that says that blow drying hair in a particular way is actually less damaging than letting it air dry. Could this be true?
The Beauty Brains respond:
The study that Mik refers to was published in the Annals of Dermatology and it does indeed conclude that “Although using a hair dryer causes more surface damage than natural drying, using a hair dryer at a distance of 15 cm with continuous motion causes less damage than drying hair naturally.”
How can air drying be bad for hair?
For the most part the article confirms what scientists have long known about hair: heat causes damage, especially damage to the shingle-like outer layer of hair known as the cuticle. But the surprising discovery by these authors is that air dried hair sustains more damage to the Cell Membrane Complex (CMC), the sandwich-y layer of proteins, lipids, and covalently bonded fatty acids that is the “glue” that binds cuticles together. Once the CMC is damaged cuticles can become dislodged more easily which leads to rough damaged hair which may eventually split and break.
This finding is surprising since you’d expect the wash/dry cycle or the heat cycle to cause more damage to the CMC than air drying. The authors hypothesize that because air drying takes so much longer some internal components of the CMC are exposed to water for much longer time. This water exposure over time causes a buckling in the CMC layer. Blow drying removes the water more quickly so the CMC doesn’t have a chance to buckle.
While this is intriguing discover there are two major caveats: first, this is a single study and one should never completely believe a surprising finding that comes from only one study; more research needs to be done. Second, even though blow drying appears to cause less damage to the CMC, it does cause MORE surface damage. Therefore you’re trading one kind of damage for another by air drying hair.
The Beauty Brains bottom line
The key finding from this study is that very long drying times may be causing heretofore undetected damage to hair. While it’s well known that fast drying at high temperature causes damage, it wasn’t recognized that slow drying at room temperature could be causing another kind of damage. Perhaps the best approach is one that minimizes drying time and minimizes temperature (e.g., using your blow drying on the cool setting.)
Reference: Hair Shaft Damage from Heat and Drying Time of Hair Dryer, Ann Dermatol. 2011 November; 23(4): 455–462.