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 on the order of L~9-15 nm for the compressed layers depending on KD3 concentration while the undisturbed layers have a thickness L~23-24 nm, independent of polymer concentration. Comparision of the measured interaction lengths of compressed and undisturbed polymer layers with previous layer thickness estimates based on rheological studies shows that the polymer layers are compressed in dense suspensions.