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

342 ingredients

Start from a concern

News

2026.10.13NEWThe First Three Signs of Aging — Preventive Skincare from Your 30s 2026.10.06NEWDesigning Moisture in Layers — Humectant, Occlusive, Emollient 2026.09.29Is PDRN (Salmon DNA) the Real Deal? Grading Regenerative Buzz Ingredients with Science

Ingredient of the Day

Houttuynia Cordata Extract

Soothing, anti-inflammatory, acne prevention, K-Beauty trend

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

Moisturizing, skin softening

Prevention of moisture evaporation, skin softening

Journal

Journal

Skin Longevity SeriesNEWThe First Three Signs of Aging — Preventive Skincare from Your 30s2026.10.13 Skin Longevity SeriesNEWDesigning Moisture in Layers — Humectant, Occlusive, Emollient2026.10.06 Skin Longevity SeriesIs PDRN (Salmon DNA) the Real Deal? Grading Regenerative Buzz Ingredients with Science2026.09.29 Skin Longevity SeriesCeramide, the Protagonist — The Science of the Lipid That Binds the Skin2026.09.22 Skin Longevity SeriesRe-examining the "28-Day Turnover" Myth Through Science2026.09.15 Skin Longevity SeriesThe 4-Week Summer Damage Recovery Blueprint2026.09.08

Skin Longevity

Don’t fight aging.

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

READ THE ESSAYS