Fig. 1. The abscissa represents water drop penetration time (WDPT) in log scale, and the ordinate represents the average depth of each 1-cm slice below ground surface. Individual results are denoted by small solid markers, while the average WDPT of the layer is denoted by a large, open similar marker. The squares represent 0 to 1 cm, circles 1 to 2 cm, triangles 2 to 3 cm, inverted triangles 3 to 4 cm, and diamonds 4 to 5 cm. The vertical dotted lines indicate the boundaries between the different repellency classes as defined in the text.