This work reviews pertinent literature in modeling by considering the water
movement in filter paper to measure capillary suction time (CST). Both the
diffusion-like and piston-like approaches are described. In addition, liqu
id saturation profiles in the filter paper for pure water and some slurries
are experimentally constructed. Experimental results indicate that the uns
aturated flow in filter paper is unexceptionable in all tests. However, the
CST correlations derived from either piston-like or diffusion-like approac
hes resemble each other in form, which is attributed to the s profile near
the wet front resembling a power-law-type behavior.