Some examples of porous surfaces include paper, untreated wood, cardboard, sponge and fabric. These porous objects have pores or empty spaces that allow outside matter, such as water, air and particles, to penetrate beyond the outer surface.
Determining the porosity of surfaces is significant in multiple fields, including manufacturing, metallurgy, pharmaceuticals, agriculture, ceramics, engineering and soil mechanics. Microporous surfaces have pore sizes that are comparable to those of molecules and are used in water management, gas separation, oil recovery and removal of organic and metal contaminants from process streams. Macropores, or large pores, allow the easy movement of water and air.