The stability of particles in solution can be quantified by measuring the Zeta potential of the particles. Zeta potential is the measurement of the electric potential at the slipping plane in the double layer surrounding a particle in liquid suspension. 

By using a specially designed cell, the Zeta potential of a flat surface can be measured through the same process as Zeta potential for particles in solution. While the flat solid surface does not contribute particles for measurement, the surface Zeta potential is measured by adding probe particles to a test solution.