How Heat Damages Human Hair

How Heat Damages Human Hair

Many women and some men are very particular about their hair. One of the ways for keeping it in shape involves applying heat, but just how much of it and for how long has been mostly left to experience. A scientist from Purdue University, Indiana, is trying to find a scientific answer.

Some people who have naturally curly hair prefer to have it straightened.

Others with straight hair want to have curls.

“It is kind of like the way I see the world, like the lens through which I see the world and I always was wondering about how we can think about this from a mechanical engineering perspective," explains Tahira Reid, assistant professor of Mechanical Engineering at Purdue University.

Hair irons can take many shapes but are essentially¹ clips or rods with heated surfaces.

“If you go to the mall right now you see an aisle² full of straightening irons, and they have terms like ion technology and twirling," notes Amy Marconnet, also an Assistant Professor of Mechanical Engineering at Purdue University.

The heat weakens or breaks a protein called keratin, responsible for the hair’s shape, and temporarily changes it. But nobody knows exactly at what level the heat can actually cause permanent damage.

“If we understand the onset³ at which that happens than we might be able to intervene before or give some suggestions before you get to that point," Reid says.

Inside a Purdue University lab, a movable flat hair iron goes over a hair strand⁴ while an infrared⁵ microscope measures the changes in the hair’s structure.

Researchers say early results are a bit inconclusive. It turns out that everyone’s hair is different and that there's no exact temperature where hair straightening becomes hair damage. For example, people with naturally curly hair can suffer more damage from heat irons than those with straight hair.

Reid says they will continue their research in the hopes of finding that heat sweet spot for stylists.

1 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

2 aisle   

n.（教堂、教室、戏院等里的）过道，通道

参考例句：

• The aisle was crammed with people.过道上挤满了人。
• The girl ushered me along the aisle to my seat.引座小姐带领我沿着通道到我的座位上去。

3 onset   

n.进攻，袭击，开始，突然开始

参考例句：

• The drug must be taken from the onset of the infection.这种药必须在感染的最初期就开始服用。
• Our troops withstood the onset of the enemy.我们的部队抵挡住了敌人的进攻。

4 strand   

vt.使（船）搁浅，使（某人）困于（某地）

参考例句：

• She tucked a loose strand of hair behind her ears.她把一缕散发夹到了耳后。
• The climbers had been stranded by a storm.登山者被暴风雨困住了。

5 infrared   

adj./n.红外线(的)

参考例句：

• Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
• Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。