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.
Source:
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