Why one cleanse is never enough — and what a second step actually removes

The chemistry of double cleansing: why two steps are necessary

Sunscreen, foundation, sebum, and oil-based pollution particles are all lipid-based substances — they dissolve in oil, not in water. Foaming and gel cleansers are water-based and struggle to break down lipid substances efficiently, particularly modern long-wearing SPF filters and silicone-based makeup. Attempting to remove these with a water-based cleanser alone requires excessive rubbing that causes micro-tears and barrier disruption. The first step of the K-beauty double cleanse uses an oil-based cleanser or cleansing oil that dissolves lipid substances rapidly and emulsifies into water for removal — no rubbing required.

What a cleanser leaves behind — and why it matters for the rest of the routine

Studies of cleansed skin show that even after thorough single-step water cleansing, residual SPF filter molecules remain in the upper skin layers — not enough to provide UV protection but enough to create a barrier to serum and moisturiser absorption. Double cleansing with an oil first removes these residues completely, leaving the skin's surface ready to receive skincare actives without interference. This is the reason K-beauty routines consistently produce results in controlled tests: the cleansing step prepares the skin for maximum absorption of subsequent products.

Oil cleanser texture and how to choose the right type for your skin

Oil cleansers come in three main textures: pure oil (fastest to emulsify, most cleansing power), balm-to-oil (richer, suits dry skin, slower to emulsify), and gel-to-oil (feels lighter, suits combination skin). All three emulsify to a milky texture when water is added and rinse off cleanly without leaving a greasy residue — a property called self-emulsification, which distinguishes modern cleansing oils from mineral oil-based products. For skin that has avoided oil cleansers due to fear of breakouts, a lightweight gel-to-oil or water-soluble formulation is the starting point.

Dear, Klairs Gentle Black Deep Cleansing Oil 150ml — available on BuyBeautyKorea →