An ink jet instrument was used to measure the drop absorption time of various ink-receiver systems. The drop absorption time is defined as the time required for the receiver to completely absorb the impinging ink drop, i.e., the drop totally penetrates into the receiver and disappears from the receiver surface. The instrument consists of a piezo printhead with drive electronics, a stage for receiver support, a strobe light, a CCD camera, imaging optics, and image capture system. The drops ejected from the printhead have a volume of about 25 pL and a velocity of about 5 m/sec. The receivers used in the measurements include both non-porous and porous receivers. Results indicate that nonporous receivers with swellable polymeric coatings have much longer drop absorption time (>30 sec) than those receivers with porous coatings (∼33-100 msec). The difference in drop absorption time between non-porous and porous receivers can be ascribed to the basic difference in the physical mechanisms of ink penetration into the receiver, i.e., diffusion of ink in the polymeric receiver versus capillary flow of ink in the porous receiver. Based on these physical phenomena, simple one-dimensional models have been developed to describe the drop absorption process in the non-porous and porous receivers. The dependence of drop absorption time on the volume of ink drop and physical properties of ink, such as viscosity and surface tension, and receiver, such as diffusion coefficient and porosity, was also derived. Comparison of model results with experimental data are presented and discussed.