Measurements performed on a benchtop polishing tool using plain commercial polyurethane chemical mechanical polishing pads and an instrumented, nonrotating stainless steel polishing head show both negative (suction) and positive fluid pressures under different regions of the head. Observations of the head attitude also show a pronounced bank of the head toward the center of the pad. By carefully characterizing the pad topography and surface mechanical properties and by the application of this physical data in a load- and moment-balanced hydromechanical theory, we show that it is possible to accurately account for the location and magnitude of fluid pressure observations and for head tilt data. The results highlight the influence of the pad radial surface height profile on fluid and solid contact pressures on plain pads. (c) 2005 The Electrochemical Society.