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2020/02/07

  • News Release
  • R&D

Novel Method for Analyzing Base Makeup Film Internal Structure Using Raman Spectroscopy for Visualization of Composition Distribution and Sebum Characteristics

This is an English translation of a news release in Japanese on January 16.

The Analytical Science Laboratory and Makeup Research Laboratory of Kao Corporation (Michitaka Sawada, President) have developed a new evaluation method that visualizes composition and distribution of each component inside the film formed by base makeup such as foundation by use of Raman spectroscopy*1 without disruption of the film. With use of this technique, composition distribution inside base makeup film as well as sebum characteristics can be revealed.
Findings obtained in this study were presented at the 85th SCCJ*2 Research Workshop in Tokyo (November 27, 2019). Kao will make use of this new evaluation method for future development of base makeup products with greater functionality.

  • * 1 Technology for visualizing composition distribution inside sample by detection of specific light generated by laser illumination used in the field of dermatology for measuring water distribution in skin.
  • * 2 Society of Cosmetic Chemists of Japan

Background

When using a cosmetic base makeup product, such as foundation or primer, 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. For 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.
Scanning electron microscopy (SEM) observation is useful for analyzing the structure of base makeup film. However, that methodology has limitations, including lack of discrimination of organic substances such as oil in cosmetic products and sebum, while it is also unable to be used to observe temporal changes inside the film. To address these issues, Kao has developed an analytical method for detailed visualization of the internal structure of base makeup film, such as its composition distribution.

Analysis of internal structure of base makeup film by Raman spectroscopy

Initially, base makeup film samples were prepared using a commonly used liquid foundation, then observed by Raman spectroscopy. However, the internal structure could not be analyzed because of destruction of the film by laser-generated heat. In addition, the Raman signals for some of the components were excessively strong, making precise visualization impossible.
Further examinations showed that iron oxide and titanium dioxide interfered with specific analysis of the base makeup. Therefore, a model formulation was prepared by replacing those with talc, which allowed for successful visualization of the composition of the base makeup film, including organic and inorganic substances, as well as distribution of each component in cross-sectional images (Fig. 1)
Those results confirmed that powder, lipophilic, and hydrophilic components formed micrometer-sized aggregations inside the base makeup film. In addition, the film was shown to be constructed by complex interactions of those components.

Fig. 1. Structure of model base makeup film
(horizontal section) 

Visualization of sebum distribution in base makeup film

Next, the behavior of sebum, a major cause of makeup deterioration, was examined as a test application of this novel technique. It was anticipated that sebum distribution in the film would be visualized by adding sebum*3 to the base makeup film prepared with a model formulation. However, the oil contained in the base makeup, including silicon and UV absorber, as well as in the sebum model could not be discriminated, thus a highly sensitive detection technique that replaced some atomic elements of the sebum model with deuterium was adopted. Using this technique, evaluation of the base makeup film was possible in terms of sebum resistance. It was confirmed that sebum was not spread throughout the film, but rather was localized between the base makeup components (Fig. 2).
The present findings suggest that base makeup film with sebum resistance can contribute to prevention of makeup deterioration due to sebum.

  • * 3 Oleic acid, triglycerides, etc.

Fig. 2. Cross-sectional images of model
base makeup film with added sebum film

Conclusion

The present novel technique clarified composition distribution and sebum behavior in base makeup film, which were previously difficult to understand or clearly observe.
Kao intends to develop highly functional base makeup products by use of this technology.

About Kao

Kao creates high-value-added products that enrich the lives of consumers around the world. Through its portfolio of over 20 leading brands such as Attack, Bioré, Goldwell, Jergens, John Frieda, Kanebo, Laurier, Merries and Molton Brown, Kao is part of the everyday lives of people in Asia, Oceania, North America and Europe. Combined with its chemical division, which contributes to a wide range of industries, Kao generates about 1,500 billion yen in annual sales. Kao employs about 33,000 people worldwide and has 130 years of history in innovation. Please visit the Kao Group website for updated information.

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