Blowdrying. Curling. Straightening. Heat has been used to control hair for hundreds of years.

But how much is too much? If you've ever opened a very hot oven, you know that heat can burn your eyebrows off your face very quickly.

A scientist from Purdue University in Indiana is trying to find a scientific answer on how hot is too hot when it comes to your hair.

Many women and some men are very particular about their hair. Some people who have naturally curly hair prefer to have it straightened.

Others with straight hair want to have curls.

Tahira Reid is one of those people. As an African-American woman, she is familiar with the challenges of maintaining curly, coil or tightly curled hair.

Putting her mechanical engineering training to work, Tahira Reid and other researchers at Purdue University are studying how heat treatment interacts with different types of hair and how to prevent damage.

"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."

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

Amy Marconnet is assistant professor of mechanical engineering. She says the team is seeing how heat and temperature relates to their research.

"If you go to the mall right now you see a whole aisle full of straightening irons, and they have terms like ion technology and tourmaline."

In a Purdue University lab, team members designed a hair straightener tool -- a flat iron with ceramic plates and temperature control. They attached it to a robotic arm that moved over pieces of hair. They monitored the temperature while the device straightened hair.

What did they find? Their study found that 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. Again, Tahira Reid.

"If we understand the onset at which that happens then we might be able to intervene before or give some suggestions before you get to that point."

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.

Ms. Reid says they will continue their research in the hopes of finding what works best without damaging the hair.

I'm Marsha James.