J. Cosmet. Sci., 71, 399–410 (November/December 2020) 399 Objective Methods for Quantifying Color Retention and Bleeding Potential of a Lipstick Through Large-Scale Panel Perception and Controlled Usability Studies DI QU, ALYSSA JOHNCOCK, and JIANWEI LIU , Amway Innovation and Science, Ada, MI (D.Q.), (A.J.), Amway Innovation and Science – East Hub, Shanghai, 201203 China (J.L.) Accepted for publication June 17, 2020 . Synopsis Color retention and bleeding are two properties of lipstick performance which impact consumer acceptability and preference. Before now, the claims of long-wear and non-bleeding had yet to be meaningfully substantiated quantitatively. Lack of objectively defi ned parameters and measurement methods inhibits one’s ability of obtaining adequate claims support. In this study, we designed a 30-member, controlled-usability study to develop methods that quantify color retention and bleeding potential. Image analysis methods were used to measure lip color properties at the time points of baseline, immediate after application, and 8 hours of wear. Large-scale panel perception studies were conducted to obtain consumer acceptability criteria and establish consumer relevance of the objectively measured parameters. Our results show that the methods developed can quantitatively describe the color properties. Eight hours after application, the mean levels of color retention and bleeding potential for this specifi c lip color were 82.67% and 2.43, respectively. The results of panel perception studies helped establish threshold values for lip color performance acceptability, that is, if a color retention level was lower than 82.7%, or a bleeding potential level was higher than 2.37, the performance would not be deemed acceptable. The methods and results reported here serve as a useful tool for the evaluation of lip color performance in future development of quality lip color formulations. INTRODUCTION The global lipstick market was worth $12 billion in 2018 and was expected to reach $17 billion by 2024 according to a 2019 report (1). Lipstick has been used for nearly fi ve thousand years as a way to enhance the texture of the lips, provide protection from the environment, and create an overall radiant facial appearance (2). The cultural, psycho- logical, and sociological implications of lipstick use have been well documented (3–7). Phenomena of consumer lipstick purchasing behavior have also been studied. In a recent report, Zhi-xuani et al. (8) researched factors infl uencing lipstick purchases among Chinese female college students. It was concluded that the types of beauty products purchased were signifi cantly affected by multiple psychological factors including their beauty- and Address all correspondence to Di Qu at di.qu@amway.com.

JOURNAL OF COSMETIC SCIENCE 400 fame-seeking motivations, as well as their emotional and diverse personality traits. Hill et al. (9) reported a lipstick effect in the United States, which concluded that women would purchase more beauty products to improve their appearance during economic downturns. Consumer satisfaction over product performance, especially long-lasting or long wear on the lips, is another important, perhaps more infl uential factor. A 2012 study in France had shown that wearing lipstick could have a signifi cant infl uence on restaurant patrons’ tipping behavior (10), and scientists in Japan had detected that wearing red lip- stick enhanced the lightness of facial skin complexion (11). Instrumental and image anal- yses of properties of skin and lips have been active, which provide important quantitative descriptions of multiple color and morphological properties (12–17). However, there is little information in the literature regarding objective measurements of lipstick color retention and bleeding potentials because, up to now, lipstick property and performance have been primarily evaluated by small panel studies or laboratory testing using non-skin surfaces and various instruments (18–20). Although those tests are quick and convenient for prototype testing, the small sample size may lead to inadequate representation of product performance when it comes to fi nal claims substantiation. Relating to measure- ment of color retention and bleeding, there was a Korean research in 2005, which exam- ined lip color tone and spread (bleeding) while studying the lip wrinkles of 20 participants (21). The emphasis was made, however, to the local area around specifi c lip lines, and the pixels showing color spread (bleeding) were manually picked and measured with assis- tance of an image analysis software. The changes in overall color retention and compre- hensive measurement of lip color bleeding were not studied. It is our belief that the objectively measured parameters from a relatively large test population (N ≥ 30) would help achieve better measurement consistency, less variability in assessing product perfor- mance, and more relevance to consumer experience. Therefore, the aim of this study was to develop methods for the objective measurement of lipstick performance with regard to color retention and bleeding properties in a controlled usability study in conjunction with a large-scale panel perception study. This would allow us to evaluate a lipstick for- mulation and derive meaningful substantiated claims to drive consumer satisfaction in the marketplace. MATERIALS AND METHODS STUDY DESIGN A liquid lip color formulation with bright red shade and silky matte fi nish was tested in our clinical testing laboratory in Ada, MI, where the temperature and relative humidity were controlled at 70 ± 1°F and 39% ± 2%, respectively. Thirty female volunteers par- ticipated in the study, with ages ranging from 30 to 63 years and of various ethnicities. They came to the laboratory in the morning and washed their face. After acclimating to the room conditions for 15 min, their frontal facial images were taken using VISIA-CR 4.3 (Canfi eld Scientifi c, Parsippany, NJ) together with a plate of color standards. These images were defi ned as the baseline (BSL) time point. They then applied the test product on their lips under the guidance of a laboratory scientist. After allowing the product to dry for 15 min, their images were taken again and were defi ned as the immediate after lipstick application (IMM) time point. The volunteers were then dismissed from the laboratory with instructions to drink beverages through a straw, cut food into small pieces