The swelling rates of desiccated beads (oven at 40 °C) in different aqueous media were followed using a zoom stereo microscope Olympus (SZ-6045-TR-F) equipped with a colour videocamera DP12 (Olympus, Japan). The degree of swelling was estimated as the ratio of the area of the projected surface of the particles, analysed with DP-SOFT software, compared to that of freshly prepared swollen beads.