The principle is rooted in a fundamental rule of chemistry: like dissolves like. Oil and water don't mix – which is why both cleansers are needed for the alignment of removal and restoration. Oil-based impurities like SPF and foundation require an oil-based medium to fully dissolve them. Water-based cleansers, however effective on their own terms, cannot break these bonds on their own.

Applied to dry skin first, an oil cleanser engages directly with these lipophilic residues, dissolving them at the surface before water is introduced. The second cleanse then addresses the hydrophilic layer – sweat, water-soluble pollutants, and residual sebum – while simultaneously emulsifying and removing any trace of the first cleanser so nothing sits between your skin and what comes next. Every serum, treatment, and moisturiser you apply works harder when the skin beneath it is truly, completely clean.