Cosmetic effects of red-light reflection by ultramarine blue pigment.

Objective: Inorganic pigments used as colouring agents in cosmetics (especially foundations) have many advantages over organic pigments, such as better opacity, weather and chemical resistance and lower cost. However, the types used in cosmetics are very limited, with various kinds of red, yellow and black iron oxide along with white titanium dioxide being the main materials. Ultramarine blue (UB) as a blue pigment and chromium oxide as a green pigment are also sometimes used in cosmetics. In this study, we focus once again on UB and reexamine the possibility of expanding the colour gamut using UB instead of black pigment and creating other optical cosmetic effects.

Methods: The effects of using UB were measured using spectroscopic instruments to determine the colour parameters when applied on artificial skin. The appearance of the product when applied to the human face was also verified both in terms of human appearance evaluation by an expert (esthetician) and numerical evaluation using imaging spectrometer measurements.

Results: The verified results showed that, at least in the colour range targeting Asian people, UB could not create a new colour gamut, but it was clear that UB could impart an optical effect that produced a beautiful skin effect on the face. This was remarkable both in the evaluation of human appearance and in the spectral measurement results, which confirmed the phenomenon "red-light makes skin look beautiful," which has been variously reported since the 2000s, using a different approach.

Conclusion: We have discovered a new possibility that UB, widely recognized as a pigment, is involved not only in colour tone but also in optical effects that contribute to the goal of beautiful skin, i.e. hiding skin wrinkles, eliminating unevenness of colour and improving skin homogeneity.