Under the layer: Kao develops new method to analyse internal structure of base make-up film

Raman spectroscopy is used to analyse and provides detailed information of the composition distribution insides sample by detecting specific light generated by laser illumination.

In the field of dermatology, it can be utilised to measuring water distribution in skin.

Kao researchers employed this technology to reveal the composition and distribution of each component inside the film of base make-up products, without damaging the film sample.

The maker of Biore and Kanebo noted that today’s base make-up products such as foundations and primers must be outfitted with a host of attributes.

“In addition to fundamental performance for providing a beautiful finish, several other attributes are important, such as long-lasting effect, comfortable feeling, smooth and even application, and UV protection,”​ said the company in a statement.

As such, it highlighted the importance of this research as it will help its formulators to develop better products in the future.

“Achieving these expectations at a highly functional level, detailed understanding of the structure and distribution of components of base makeup film formed on the skin, as well as the processes involved in its formation and disruption is very important.”​

The findings obtained in this study were first presented at the 85th Society of Cosmetic Chemists of Japan (SCCJ) Research Workshop in Tokyo last November.

Visualising the internal structure​

Previously, scanning electron microscopy (SEM) observation was used to observe the structure of the film.
However, Kao pointed out that the methodology had its limitations, including being unable to discriminate between oil in cosmetics and sebum, as well as observe temporal changes inside the film.

According to the Japanese company, the Raman spectroscopy technique will also allow researchers to analyse the film’s interaction with sebum as well.

To further analysis the base make-up, iron oxide and titanium dioxide were replaced with talc, which allowed for successful visualisation of the composition.

The scientists explained that the iron oxide and titanium dioxide were replaced as they interfered with specific analysis of the base make-up.

The results of the experiment confirmed that powder, lipophilic, and hydrophilic components formed micrometre-sized aggregations inside the base makeup film.

In addition, the film was shown to be constructed by complex interactions of those components.

The cause of make-up breakdown

In order to observe the interaction between make-up and sebum, the team developed a highly sensitive technique that replaced some atomic elements of the sebum model with deuterium.

The results from the tests confirmed that sebum was a major cause of make-up deterioration, suggesting that base make-up with sebum resistance can contribute to the prevention of makeup deterioration.

Kao said it intends to employ this method in its future development of ‘highly functional’ base make-up products.

“The present novel technique clarified composition distribution and sebum behaviour in base makeup film, which were previously difficult to understand or clearly observe. Kao will make use of this new evaluation method for future development of base makeup products with greater functionality.​