Hard water vs. foam performance

A recent study conducted by L'Oréal's Research & Innovation division in India highlights the detrimental effects of hard water on the stability of foaming cosmetics, underscoring the importance of taking this parameter into account in the formulation process. Dissolved ions weaken the internal structure of the foam, accelerating bubble coalescence, drainage, and the loss of elastic properties. On a macroscopic scale, the viscosity of the foam does not vary significantly between soft and hard water, indicating that water hardness mainly influences stability and longevity, rather than immediate tactile perception.