How Long Should You Give a New Korean Skincare Product Before You Judge It?
Hydration shifts in hours, barrier repair over days, turnover in about 36 days. A Seoul studio on when a new product has actually had its chance — and the one studio rule we give away in full.
Why Does Skincare Sting? What That Sting Tells Us — and What It Doesn't
A sting means something reached your nerve endings faster than your skin could buffer it. In one study of 209 healthy women, two-thirds stung on a standard lactic acid test.