When an indenter is pressed into a gel to a fixed depth, the solvent in the gel migrates, and
the force on the indenter relaxes. Within the theory of poroelasticity, the force relaxation
curves for indenters of several types are obtained in a simple form, enabling indentation to
be used with ease as a method for determining the elastic constants and permeability of the
gel. The method is demonstrated with a conical indenter on an alginate hydrogel.