How We Read an Ingredient Label at Seoul Skin Archive

When a product lands on our desk for evaluation, the first thing we check isn't the packaging or the brand story. It's the International Nomenclature of Cosmetic Ingredients (INCI) list — the full, ordered declaration of every ingredient from highest to lowest concentration.

Concentration tells you the actual formula

Ingredients are listed in descending order of concentration. If niacinamide appears fourth on the list, it's a meaningful concentration. If it appears fifteenth — after fragrance, thickeners, and stabilizers — it's window dressing. We don't count ingredients; we look at where they land.

This is the most common gap between what a product claims and what the formula actually delivers. A brand can market a product as a "vitamin C serum" while L-ascorbic acid appears at position twelve. We mark that as a concern.

What we check beyond position

pH-sensitive actives: L-ascorbic acid (vitamin C) requires a pH below 3.5 to function. We check whether the formula's other ingredients are compatible with that requirement.
Fragrance placement: Fragrance is the leading cause of contact sensitization in skincare. We note whether it appears and where — especially for products targeting sensitive skin types.
Penetration enhancers: Some ingredients (like propylene glycol) increase absorption of everything that follows. Beneficial with actives, potentially problematic with irritants.
Preservative systems: We look at what's keeping the formula stable. Parabens are not automatically disqualifying — the alternatives are sometimes worse for reactive skin.

Why this matters for the archive

Every Seoul Skin Archive candidate is cleared at the ingredient level before it reaches the product pool. This is slower than curating by brand reputation or review score, but it's the only method we've found that produces boxes where every item is actually appropriate for the skin type it was matched to.