Hanluvi — The Korean skincare routine (K-beauty): the | hanluvi.com
The concentrations these actives are actually dosed at, the pH conditions they need, and how often each one is used.
Niacinamide serums are commonly dosed at 2-5%, with stronger leave-on products at 10%. It is the most forgiving active in the routine: it sits in the serum slot morning or night and pairs with almost everything, which is why 2-5% used daily tends to outperform a 10% bottle used sporadically.
Vitamin C as L-ascorbic acid typically runs 10-20% and only performs well in formulas below pH 3.5. That acidity requirement is why it goes onto freshly cleansed skin, and most routines give it the morning slot, where it sits under sunscreen.
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Retinol is the slow game. Starters use 0.25-0.5% and step up to 1% only when the lower strength is tolerated; about 12 weeks of nightly use should pass before results are judged. It belongs to the evening, and nights alternate with exfoliating acids rather than stacking with them.
Salicylic acid (BHA) rounds out the core four: leave-on exfoliants are formulated at 0.5-2%, while rinse-off washes run milder at 0.5-1%. Two or three nights a week is the standard cadence for the leave-on form.
The environment matters as much as the percentage. Skin sits at pH 4.5-5.5, and a cleanser above pH 7 disrupts the acid mantle that every active depends on — so the gentle second cleanse of the 10-step routine in order is part of the dosing strategy. And because several actives increase sun sensitivity, the SPF and PA ratings guide covers the protection that has to sit on top.
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