Our research on friction mechanisms has shown that the frictional force between sliding surfaces at moderate speeds and loads is primarily due to mechanical effects, such as plowing of surfaces by entrapped wear particles. In the absence of mechanical interactions, the coefficient of friction is extremely low. In this paper, one way of eliminating mechanical interactions is presented. Hard, smooth single crystal silicon wafers were dip coated in aqueous polyurethane dispersions. The film thickness was varied from 90 to 250 nm by diluting the elastomeric material with different amounts of water, yielding a mean surface roughness comparable with that of the substrate, i.e. 3 nm. Borosilicate glass balls, 4 mm in diameter, were used as the counterface. An ultra-low friction coefficient of 0.04 in dry sliding was achieved through an appropriate selection of film thickness and crosslinking density. The friction coefficient of such films is dependent on the normal load, exhibiting a minimum friction coefficient under a specific normal load. Higher loads result in tearing of the surface, whereas at low loads the viscoelastic losses of the surface layer contribute to the increase in the coefficient of friction. Under the optimal normal load and film thickness, there is no visible damage to the surface after the friction tests. However, atomic force microscopy of the tested surfaces revealed that, even when the friction coefficient was as low as 0.05, the surface of the films was plowed. In general, a higher friction coefficient corresponds to greater surface damage.