Influence of bulk and surface interactions from thick, porous, soil-based substrates on the spreading behavior of different viscosity oils

preading area through a 1.3 cm deep matrix was reduced with increased moisture content, densely packed matrixes, and higher viscosity oils. Initial contact angle (CA) measurements for all oils was typically lower on clay matrixes due to its sheet-like structure and high absorption capabilities. Individual droplet penetration took longer at lower MC in direct contradiction to bulk kinetics studies, suggesting different spreading behavior across the surface border.