The steric repulsion induced by adsorbed layers of the commercial dispersant Hypermer KD3 has been probed by direct measurements in decalin. The forces are long range (commencing at 30-40 nm) and repulsive, and the distance dependence can be modeled with a simple scaling theory expression valid for polymer brushes. We obtain layer thicknesses of similar to 9-15 nm for the compressed layers, depending on KD3 concentration, whereas the undisturbed layers have a thickness of similar to 23-24 nm, independent of polymer concentration. Comparison of the measured interaction lengths with previous layer thickness estimates based on rheological studies shows that the polymer layers are compressed in dense suspensions.