Study on macroporours IX resins and the pore structure. In addition to ion exchange reactions, macroporous ion exchange resins also show adsorptive properties which are due to the large pores of the resin beads and to the inner surface inside the beads. To measure this surface and the pore radii requires very precise fixation of the condition existing prior to the drying of the water-moist resin beads. Such stabilizing fixation can be achieved by displacing the regain water by isopropyl alcohol and subsequent drying for measuring the pore data.