Cosmetic Science Library

Answering the “why” of
cosmetics, with science.

A library where you learn cosmetic science. Aiming to be the definitive cosmetic-science library.

Explore the Library

324 ingredients

Start from a concern

News

2026.09.08NEWThe 4-Week Summer Damage Recovery Blueprint 2026.09.01The Season-Change Switch: How the Autonomic Nervous System and the Skin Barrier Move Together 2026.08.25Grading the Buzzwords of Brightening Skincare

Ingredient of the Day

Hydrolyzed Hyaluronic Acid

Its reduced molecular size makes it blend easily into the stratum corneum, giving a sensation of moisturizing from within.

Ingredients

Featured Ingredients

Ceramide NP NS AP

Barrier function repair, TEWL reduction

Niacinamide Vitamin B3

Wrinkle improvement, melanin suppression, barrier strengthening, NAD+ precursor

Vitamin A (Retinol)

Turnover promotion, collagen synthesis, wrinkle improvement

Vitamin C (Ascorbic Acid)

Antioxidant, collagen synthesis (cofactor for proline hydroxylation), melanin suppression

An amino acid that replenishes the natural moisturizing factor of the stratum corneum and imparts a moist feel

Moisturizing, skin softening

Journal

Journal

Skin Longevity SeriesNEWThe 4-Week Summer Damage Recovery Blueprint2026.09.08 Skin Longevity SeriesThe Season-Change Switch: How the Autonomic Nervous System and the Skin Barrier Move Together2026.09.01 Skin Longevity SeriesGrading the Buzzwords of Brightening Skincare2026.08.25 Skin Longevity SeriesThe 3-Day Obon Reset ── A Concentrated Rest Protocol for Sun-Tired Skin2026.08.18 Skin Longevity SeriesThe Invisible Dryness Under Air Conditioning — The Science of TEWL and Barrier Function2026.08.11 Skin Longevity SeriesThe Science of Summer Acne—Sweat, Sebum, Clogged Pores, and the Ecology of C. acnes2026.08.04

Skin Longevity

Don’t fight aging.

KAIAN’s way of rethinking the relationship between skin and time.

READ THE ESSAYS