text: The main application of DVS is to measure water sorption isotherms.  In general, a vapor sorption isotherm shows the equilibrium amount of vapor sorbed as a function of steady state relative vapor pressure at a constant temperature.  For water sorption isotherms, water-relative vapor pressure is more commonly expressed as relative humidity. This is accomplished  in a DVS measurement by exposing a sample to a series of step changes in relative humidity and monitoring the mass change as a function of time.  The sample mass must be allowed to reach gravimetric equilibrium at each step change in humidity before progressing to the next humidity level.  Then, the equilibrium mass values at each relative humidity step are used to generate the isotherm.  Isotherms are typically divided into two components: sorption for increasing humidity steps, and desorption for decreasing humidity steps.  Sorption can be further divided into adsorption (sorbate located on the surface) and absorption (sorbate penetrates the bulk).