Science

Sunscreen Is a Surface Strategy

A mineral SPF is the one product in a routine that is formulated to do the least, in the specific sense that matters here: stay on the surface.

What ‘Penetration’ Actually Means

Skincare copy uses "penetrates deep" as a blanket compliment. In real formulation terms, the depth an ingredient reaches is a specific, testable, and often deliberately limited property.

Why the Corneum Isn’t the Enemy

Exfoliating acids are marketed against the outermost layer of skin as if it were dead weight. It is dead -- and that is exactly why it matters.