ABSTRACT
The contact angle method still remains the most accurate force balance methodology for measuring the interaction between two surfaces at the minimum equilibrium distance, = o (i.e., at molecular contact). But for determining the rate of decay of the interaction with distance, , one has to apply the various theoretical rate of decay rules which apply to each different interaction mode. However, one can measure the force of attraction between two surfaces, in air, or in vacuo, or immersed in a liquid, as a function of distance, , by means of a mechanical force balance.
