Skincare science
Skincare science, decoded.
Ingredient-led reads on K-beauty actives, new exfoliants, and the science behind what actually works — written for people who read labels.
Ingredient guides & skincare reads
From Korean clinic favourites to the acids in your face wash — plain-language science for ingredient-aware buyers.
Copper peptides: collagen signalling, explained
Copper peptides (GHK-Cu) are short chains of amino acids bound to copper — a combo that signals your skin to produce more collagen and elastin. They're gentler than retinol but still support firmness, wound healing, and barrier recovery. The catch: they don't play well with strong acids or vitamin C at low pH — use them on alternate nights or in a dedicated PM step. Look for concentrations around 1–2% in serums for meaningful results.
Read on The CutPHA (Polyhydroxy Acid): exfoliation for sensitive skin
PHAs like gluconolactone and lactobionic acid are the gentlest exfoliants in the acid family. Their larger molecular size means they penetrate slowly — less sting, less irritation, more barrier-friendly. They still dissolve dead skin cells, improve texture, and provide antioxidant benefits. Ideal if AHAs or BHAs leave you red and tight. In a triple-acid wash (AHA + BHA + PHA), PHA is the safety net that keeps daily use possible.
Read on ByrdieWhy AHA, BHA, and PHA together actually make sense
AHAs (glycolic, lactic) work on the skin surface — brightening and smoothing. BHAs (salicylic acid) are oil-soluble, so they penetrate pores and target blackheads. PHAs exfoliate gently while hydrating. Used together at sensible concentrations, they cover more skin concerns in one step than any single acid alone. The key is formulation: a rinse-off cleanser limits contact time, making a triple-acid system safe for daily use for most skin types.
Read on Soko GlamNiacinamide at 5%: the dose that actually works
Niacinamide (vitamin B3) is one of the most studied skincare actives — and 5% is the sweet spot for visible results on pores, oil control, and uneven tone. It strengthens the skin barrier, reduces transepidermal water loss, and calms redness. Unlike many actives, it plays well with most ingredients. Higher isn't always better: studies show 5% matches or outperforms 10% for sebum regulation without increasing irritation.
Read on Chemist ConfessionsCentella Asiatica (Cica): Korea's calming staple
Centella — also called Cica or tiger grass — is a K-beauty cornerstone for sensitive and compromised skin. Its active compounds (asiaticoside, madecassoside, asiatic acid) reduce inflammation, support wound healing, and strengthen the moisture barrier. You'll find it in everything from toners to post-procedure creams. It pairs well with actives like retinol or acids by reducing the irritation they can cause. Look for it high on the INCI list, not buried at the bottom.
Read on VogueSnail mucin: hydration with a side of repair
Snail secretion filtrate isn't as strange as it sounds — it's a mix of glycoproteins, hyaluronic acid, and glycolic acid that hydrates, soothes, and supports skin repair. Korean brands popularised it for the 'glass skin' look: plump, dewy, healthy. It works for most skin types, including sensitive, because it's inherently reparative. Use it as an essence or serum layer before moisturiser — especially if your barrier feels stripped from over-exfoliation.
Read on MediumBakuchiol: the retinol alternative worth knowing
Bakuchiol is a plant-derived compound that mimics retinol's effects on collagen production and cell turnover — without the dryness, peeling, or sun sensitivity. It's safe during pregnancy (unlike retinol) and can be used morning or night. Studies show comparable improvements in fine lines and hyperpigmentation over 12 weeks. It won't replace prescription retinoids for severe acne, but for anti-ageing maintenance, it's a credible, gentler option.
Read on ByrdieSee what's in our formulas
Read the full ingredient breakdowns for every Reluctant product — concentrations included, marketing fluff excluded.
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