No abstract

Application of colloid stability theory to soil redeposition in detergent liquors has enabled the formulation of a working hypothesis for the effect of polymeric additives on the process. Ionogenic additives are presumed to function by increasing the electrical repulsive forces between soil and fabric, while nonionogenic or weakly ionogenic addi tives may decrease the attractive dispersion forces or increase the nonelectrical repulsive forces. The electrical repulsive force is inferred from soil redeposition tests to be at a maximum when the zeta potentials of soil and fabric are equal in sign and magnitude. As the difference in zeta potential between the two substrates is increased, an attractive force results, even though the sign of the zeta potential is the same for both substrates. This behavior is attributed to an induced charge effect.