The Colloid Physics of Micelles: What Actually Happens on Skin
Micelles are microscopic spherical aggregates formed by surfactant molecules. Each molecule has a hydrophilic (water-loving) head facing outward and a lipophilic (oil-loving) tail pointing inward.
When you wipe a soaked cotton pad across your face, the micelles break open. The oil-loving tails grab onto sebum, foundation, and waterproof pigments, rolling back into spheres that trap the dirt inside. However, when the water solvent evaporates, some surfactant molecules and trapped makeup particles remain deposited on your stratum corneum. Over hours, residual surfactants can disrupt the intercellular lipid bilayers, leading to micro-irritation and clogged pores.
The Dermatological Verdict: To Rinse or Not to Rinse?
If you are camping, traveling on a plane, or in an emergency, leaving Bioderma on your skin is infinitely better than sleeping in makeup.
However, if you are at home beside a sink, taking 15 seconds to rinse with lukewarm water (or following with a gentle water-based wash as Step 2 of a double cleanse) removes all emulsified makeup residue and surfactant ions, leaving your skin truly clean and receptive to serums.