Fig. 5

Liquid-phase water permeation observations during dye-solution permeation experiments. Use bark pieces with a, d thin, smooth; b, e thick, smooth; and c, f rough outer-bark surfaces. White dashed lines indicate outer-bark surface contours; white and gray bars indicate inner and outer bark, respectively; white arrows indicate outer-bark exfoliation; red shading indicates dye permeation, as determined by image processing. The black lines marked on the centers of bark pieces a and b are reference lines for the measurement of the pieces’ thickness. The scale length in all photos is 1.0 mm