protective action

in colloid chemistry
Addition of small amounts of hydrophilic colloid to a hydrophobic sol may make the latter more sensitive to flocculation by electrolyte. Higher concentrations of the same hydrophilic colloid usually protect the hydrophobic sol from flocculation. This phenomenon is called protective action.
PAC, 1972, 31, 577. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry' on page 610 (