Acetum

Acetum is the INCI name for acetic acid, most commonly derived from fermented sources such as vinegar. In skincare formulations, it functions primarily as a solvent and pH-buffering agent rather than as an active ingredient targeting specific skin concerns.

Its role in cosmetic products is largely technical: it helps dissolve other ingredients, adjust formulation pH to optimal levels, and maintain product stability. It is not typically included for direct skin benefits.

Acetum works as a weak acid, meaning it can donate hydrogen ions to adjust the pH of a formulation towards acidity. This is important because skin naturally sits at a pH of around 4.5–5.5 (acidic), and skincare products formulated at this pH tend to be better tolerated and more effective.

As a solvent, acetum dissolves both water-soluble and some lipid-soluble compounds, allowing formulators to create stable, homogeneous products. Its antistatic properties help reduce unwanted electrical charge that can affect product texture and feel.

Acetum is a background ingredient in finished products and not something you would apply directly. Simply use products containing it as directed by the manufacturer. Its presence is a sign of thoughtful formulation rather than a marketing feature to prioritise when choosing a product.