Article By Dr. Xuzi Kang Postdoctoral Fellow at TRI Princeton
Ever wonder why the same lipstick looks different on you and your friends? It's not just about the color in the tube; it's a game of “mix and match” with your skin tone. Dr. Xuzi Kang from TRI has been exploring this fascinating interaction and learning how human eye perception and lipstick shades interact.
Color theory of lipsticks:
Like the color theory used in painting, lipstick color theory is a blend of art and science that guides the creation and selection of lipstick shades.
The First Layer - Skin Tone Sets the Stage:
Think of your skin as the canvas and the lipstick as your paint. That first swipe is where the magic begins. Your skin's undertone plays a crucial role here, subtly shifting the lipstick's appearance. A cool undertone might give red lipstick a pinkish hue, while a warm undertone might make it appear more coral.
More Layers, More Drama:
As you layer up, the lipstick starts to reveal its true colors. But even then, your skin tone is like a subtle filter, influencing our perception. This effect is why lipstick might look slightly more intense on lighter skin.
The Color Perception Game:
Our eyes are not just viewers; they're interpreters. They perceive color in context, influenced by surrounding shades. This is why the same lipstick can appear to be a different shade against different skin tones. It's all about how the color interacts with the skin's unique palette.
Delta E (ΔE)
Delta E (ΔE) is a metric that quantifies the difference between two colors in a color space. It's a measure of perceptual color difference, essentially representing how much two colors deviate from each other to the human eye. The term 'delta' signifies a difference or change, while 'E' stands for 'Empfindung,' which is German for 'sensation' or 'perception. Delta E values below 1 represent a barely noticeable color difference to the average person when the colors are separate. In commercial reproduction, a Delta E of 3 to 6 is acceptable, though noticeable to print and graphic experts. Delta E is calculated between skin color and applications to show the color differences with different application layers.
Sample lipstick is applied 0.5 (one swipe), 1, 3, and 5 rounds on the inner arm of panelists with Type III and Type VI skin according to the Fitzpatrick skin scale. A portable colorimeter is used to measure the colors of the lipstick application (Figure 1). Delta E is calculated and compared between skin colors and sample applications (Figure 2). We can see that when zoomed in, the skin colors are very different (Delta E is 18.1), but after applying 5 rounds of the lipstick, the colors are almost the same (Delta E is 2), although, from Figure 1, they look very different with different skin color as the background.
Its significance for claims:
Complementing Skin Tones: By applying color theory, R&D teams can develop a range of shades designed to complement various skin tones. This is crucial for claims like "flattering for all skin tones" or "universal shades." Understanding the interactions between lipstick colors and skin undertones (cool, warm, or neutral) allows for creating shades that enhance natural beauty.
Color Accuracy and Consistency: Color theory ensures that the pigment in the lipstick translates accurately from the tube to the lips. This is essential for claims like "true-to-color" applications. It involves studying how different pigments mix and how they appear when applied, ensuring consistency between batches.
Color Correction Properties: Some lipsticks are formulated with color correction in mind, using principles of color theory to neutralize discolorations or pigmentation in the lips, supporting claims like "color-correcting lipsticks."
☺ At TRI, we offer lipstick testing that measures the properties of the lipstick stick itself (hardness, stickiness, and melting behavior), lipstick spreadability (pay-off and layering friction), color effects, lipstick transfer and longevity, and lip hydration. For details, refer to our previous blogs:
We are pleased to announce that TRI is starting a promotion season for lipstick testing starting now, enjoy a 10% discount for orders placed before June 30th, 2024!