Mixing 21 and 23: the two-refill trick when you sit between Korean shades 21호·23호
If 21 looks ashy and 23 looks a touch warm or deep, many people keep both refills and mix on the puff or in a spare compact. It is not a colour-theory degree — it is a way to track seasonal tan. Letters (N, W, C) still differ by brand, so mix within one line rather than across two cushions with the same number.
How to mix without making mud
Press once of each on the back of the puff, then press into the face. You can also decant a little of each into an empty compact if you will use it up inside the PAO window. Stirring huge amounts in a bowl wastes product and hygiene.
Seasonal shift
Summer often wants more 23, winter more 21, if those numbers even describe your depth. Re-check in daylight when you change climate, not only when you change country.
Undertone still matters
Mixing two mismatched undertones can grey out. If 21N and 23W pull in opposite directions, a single better-matched product beats a blend. The number is an in-brand ladder, not a universal standard.
Hygiene
Two puffs in one compact is a microbial party. Wash or rotate puffs, close the lid, and respect the open-jar months. A blend you never finish is more expensive than one shade you wear up.
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🙋 People also ask
What is the difference between essence and serum?
In Korean skincare, essence is typically a thinner, hydration-focused layer that preps skin, while serum is more concentrated with targeted actives like vitamin C or niacinamide. Essence usually comes first; serum follows. The line between them blurs, and not every routine needs both.
What is the difference between AHA and BHA?
AHAs like glycolic and lactic acid are water-soluble and work on the skin's surface to brighten and smooth, while BHA like salicylic acid is oil-soluble and gets into pores. In Korean skincare both are used sparingly, a few times weekly, always with daily sun protection.
What is a cushion foundation?
A cushion foundation is a Korean makeup innovation: liquid foundation soaked into a sponge inside a compact, applied with a puff for a dewy, buildable, skincare-infused finish. Many include sun protection and hydrating ingredients, blurring the line between makeup and skincare.
What is the difference between essence, serum and ampoule?
Essence is the lightest and most hydration-focused, serum is more concentrated and targeted, and ampoule is the most concentrated of the three. The boundaries are marketing convention, not regulated definitions.
✍️ Written & reviewed by the KoreaPlus Editorial team — dermatologist-informed, cosmetic-science researched & source-cited. Last reviewed: 2026-08-28.
General educational information using cosmetic structure-function wording — not medical advice. Always patch-test new actives. © KoreaPlus.