Glossary · Labelling & formulation
A measure of acidity or alkalinity on a scale of 0 to 14. The skin surface is mildly acidic, typically around pH 4.5 to 5.5. Formula pH affects stability, preservative performance, skin tolerance and how well some actives work: L-ascorbic acid and alpha hydroxy acids, for example, are more effective at low pH.
Getting this right early shapes the formula, the label and the claims, and avoids costly reformulation once a product is close to launch.
Guires CSL formulation, testing, clinical and regulatory teams work with pH on client projects every week, from the first brief to the final product file.
FormulationRelated terms
The standard ingredient names used on cosmetic labels in the EU, US, ASEAN and many other markets, assigned by the INCI committee of the Personal Care Products Council.
Read definition →The ISO guidelines on technical definitions and criteria for natural and organic cosmetic ingredients (Part 1, 2016) and the way to calculate natural and organic origin indexes for ingredients and products (Part 2, 2017).
Read definition →A dispersion of oil and water held together by emulsifiers, either oil-in-water (most lotions and creams) or water-in-oil (richer, water-resistant textures).
Read definition →How a product flows and deforms: viscosity, yield stress and shear thinning.
Read definition →Regulations and standards are listed first, then peer-reviewed literature. Sources checked October 2026.
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