Glycerin
Glycerin is the single most-studied humectant in skincare — cheap, stable, and effective at pulling water into the skin's surface. It's the workhorse hydrating ingredient behind most moisturizers, even when a fancier ingredient gets top billing on the label.
How to introduce it
7x
Starting / week
7x
Target / week
—
Ramp period
4w
Fair to judge by
Rules that don't bend
- Apply to damp skin, then seal with moisturizer — on dry skin in low humidity it can pull water from the skin instead of the air.