A thin, water-based cosmetic vehicle with little or no oil phase, used to carry water-soluble ingredients onto skin. It usually contains a humectant, a preservative system and a thickener. The base decides whether a peptide stays dissolved and stable in the bottle. It does not decide how much reaches living tissue.

Why it matters here

Cosmetic records state a percentage in the base. That is a concentration in the bottle, and the amount getting past the skin barrier is a separate and usually unmeasured question.

Also called

• serum base
• aqueous base
• water phase

Serum base, aqueous base and water phase all name the same water-side vehicle. In formulation work, water phase can also mean one half of an emulsion rather than a finished product.

Compounds carrying this term

None on file yet. This term is in the controlled vocabulary but no compound record currently uses it — which is a statement about our coverage, not about the term.

See also

• Cream or Gel Base — Vehicle / Diluent
• Topical — Route of Administration