New findings will help provide clearer strategies for optimizing hair care products. Quanjing

"Bad hair days" could soon become a thing of the past, according to German researchers who say they have unsnarled the mystery of frizzy and tangled hair.

The chemists from the University of Bayreuth claim they have developed the first detailed microscopic analysis of what happens to individual hair fibers when they interact with each other, which is to say when they get tangled up with each other and refuse to untangle.

The research could pave the way for the development of improved shampoos, conditioners and other products for repairing damaged hair, according to the findings.

In the new study, the researchers invented a unique technology for analyzing hair that involves mounting individual hair fibers on a cantilever tip of an atomic force microscope and measuring their interactions as they touch each other.

"The system will allow scientists to explore how different hair care products affect hair-to-hair interactions so that these products can be optimized in a more systematic fashion," says study co-author Eva Max, a doctoral student in chemistry at the University of Bayreuth in Germany.

She says the research involves "haptics", the science of touch - how the subjective perception of touch connects to objective surface properties of hair and other materials.

The researchers used this new technique to analyze hair samples to be collected from volunteers. The samples, which were previously bleached, ranged from light blond to dark blonde in color.

The researchers found that hair feels rough and difficult to comb for two main reasons. On the one hand, mechanical damage to a hair's surface or cuticle, creates scaly projections that jut out at perpendicular angles to other hair fibers. When hair fibers slide past each other, these scales create more friction than smooth hairs, causing a rough feel and making hair more difficult to comb. To soften hair, conditioners must contain active agents to smooth-out these scales so that they produce less friction, the researchers say.

On the other hand, chemical changes occur when hair fibres interact. Negative charges build up on the surface of hair that causes repulsion between single hairs. This repulsion causes friction and makes hair rough and difficult to comb. To solve the problem, positively-charged polymers that neutralize the negatively charged surfaces are included in conditioner formula to provide a silky feel to hair.

But finding the right formula for repairing damaged hair is no easy task, notes Dr Claudia Wood, a senior scientist at BASF in Bayreuth, Germany. In addition to hair interactions, many other external factors, such as humidity, water content of hair, and hair stickiness, all affect hair quality, Wood says.

The key to repairing these processes is to find the right ratio of beneficial components in a conditioner or shampoo that optimize hair feel, Max and colleagues say.

DPA

(China Daily 09/03/2008 page19)