Research on the intrinsic mechanism of the darkening of liquid foundation

Abstract

Background To investigate the intrinsic mechanism that causes the darkening of liquid foundations. Materials and method A total of 36 commercial liquid foundations were firstly studied for preliminary screening of influencing factors. A basic liquid foundation was developed for controlling variables to study the influence of each single factor. These samples were evenly spread on the standard opacity charts with the thickness of 100 μm and applied onto human inner forearm skin with the dosage of 2 mg/cm2. The discoloration of each sample was continuously recorded using spectrophotometers and reported in the CIE 1976 L*a*b* color space for at least 120 min, and ΔE was calculated to describe the severity of darkening. Results One hundred twenty‐minute ΔE of all commercial foundations was highly negatively correlated with their 120‐min ΔITA° (R2 = 0.88, p < 0.01). A strong positive correlation was found between the severity of darkening and the volatilization of the basic foundations (R2 = 0.83, p < 0.01). And the darkening of silicone‐based basic foundations using pigment coating with silicon is weaker than those without silicon (p < 0.05). Conclusion The process of the discoloration of liquid foundation is accompanied by the decrease of ITA° and manifested as darkening. The volatilization rate of the product and the coating method of the pigments used in the formula can noticeably affect the darkening of the liquid foundation.

Investigating the impact of sebum secretion on liquid makeup foundation darkening and its solution

“…The observed darkening of the foundation is attributable to the imbalance between the volatilization of solvents and the addition of sebum. Without any artificial sebum, the foundation appears darker, aligning with our previous study which indicated that the rate of darkening of a liquid foundation correlates positively with its rate of volatilization [5]. When the sebum amount was minimal, the volatilization of the liquid foundation resulted in darkening due to an increase in pigment concentration.…”

“…According to the previous study, there is a strong positive correlation between the darkening of base makeup and its volatility [5]. In correspondence with the volatility, the secretion of sebum could be considered as a process of solvent supplementation to the liquid foundation.…”

“…Our previous research on foundation darkening suggested that foundation darkening has a positive correlation with the volatility of the products. Additionally, it was discovered that silicone‐based foundations, when using pigments treated with silicone, exhibit a reduced tendency for darkening compared to using non‐silicone‐treated pigments [5]. In a study by Ogihara et al., it was noticed that pigment infiltration due to sebum secretion can cause colour makeups to darken.…”