AN EXPERIMENTAL-STUDY OF THE RADIAL PENETRATION OF LIQUIDS IN THIN POROUS SUBSTRATES

We present the results of an experimental study of the radial capillary penetration of liquids in thin porous substrates. In particular, we examine the effect of the size of the liquid reservoir on the rate of radial spreading. For capillary penetration from an infinite reservoir, the experimental data are found to be in good qualitative agreement with Marmur's model (J. Colloid Interface Sci.124, 301 (1988)). In the case of spreading liquid drops, both phases of spreading seem to follow Gillespie's prediction (J. Colloid Sci. 13, 32 (1958)) of a t-5/6 dependence of spreading rate on time. © 1993 Academic Press, Inc.