The search for shampoos, conditioners and gels that can banish bad hair days for good has been advanced by the development of the first tool that can analyse how individual fibres of hair interact at a microscopic level.

The new approach to hair imaging is starting to reveal the details of how and why hair feels different to the touch, which should assist cosmetics companies to design innovative products that make damaged hair smooth. The system has already been used to highlight two main reasons why hair often feels rough and difficult to comb, providing insights that could be used in haircare product development.

Although the global market for hair care is estimated to be worth more than £30 billion, many products are based on rudimentary science. The effectiveness of shampoos, conditioners, mousses, sprays and gels is generally demonstrated by a comb test, which involves measuring the forces required to comb hair under standardised laboratory conditions.

Eva Max, a doctoral student in chemisty at the University of Bayreuth in Germany, who is leading research into the technology, said: “There's a growing need to make hair feel more natural. However, researchers still are scrambling to put hair care on a firm scientific footing.”

The technology is based on haptics - the science of touch - and aims to establish how subjective perceptions of feeling relate to the objective surface properties of hair.

“For the first time, we present an experimental set-up that allows measuring the subtle forces, both physical and chemical, that arise when single hairs slide past each other or are pressed against each other,” Ms Max said. “The findings will help to provide clearer strategies for optimising hair care products.”

In a study presented to the American Chemical Society's conference in Philadelphia, her team has used an extremely high resolution microscope, called an atomic force microscope, to examine individual hair fibres and to measure how they interact.

“Everybody has experienced the effect of hair conditioners which make hair smooth, pleasant to touch and easy to comb,” the scientists said. “Still, the reasons for the ‘silky touch' that is achieved by hair conditioning are still not well understood.”

The researchers used the system to analyse samples of bleached hair taken from volunteers. They identified two reasons why it feels rough and can be hard to comb. The first was that damage to the hair's surface, or cuticle, creates scaly projections that jut out at right angles to the hair's main shaft. When hair fibres slide past each other, the projections catch, creating extra friction. This suggests that conditioners need to be formulated to contain agents that can soften or remove these scales.

The other effect is caused by negative electrical charges that build up on the surface of hairs, which

leads them to repel one another. This adds to friction and makes hair feel rougher. Positively charged polymers could be added to conditioners to counteract this.

Ms Max said: “The system will allow scientists to explore how different products affect hair-to-hair interactions, so that these products can be optimised in a more systematic fashion.”

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