A new description for the pigment volume concentration (PVC) is given. It is based on the average effective density of the aggregated particles as they are present in dispersions, coating layers, and oil absorption pastes. The average effective particle density can be measured by mercury porosimetry. In this paper, the model is applied to pigment powder packings. Oil absorptions are contributed by the average effective particle density, the packing of the particles, and the wettability of the particles by the oil. -- AATA