which was confirmed using SEM imaging. The spherical pores are formed during slow reactions under atmospheric pressure, while anisotropy is introduced during rapid foam synthesis (Petrovic et al., 2005; Prociak et al., 2014). In the case of examined materials, the pores were elongated in the direction parallel to the foam growth direction, with the shape anisotropy index in range of 1.21–1.28. The materials characterised by lower apparent densities and greater average pore sizes exhibited greater pore shape anisotropy(Table8).The SEM imaging allowed for a more in-depth under standing of the physical properties of the examined materials by indicating that the lower compressive strength oft he 25PP/75RP and 100RP was not only a result of the plasticising effect of the plant-based polyol but also the more disordered porous structure of the RPUF.Moreover the 25PP/75RP and 100RP materials contained a significant number of the biggest pores ca. 2000m in diameter (Fig. 9), which explains the reduced compressive strength of these materials as well as the increased friability.The homogenous structure of the 50PP/50RP material combined with the good mechanical properties and the high renewable material content confirmed the 50PP/50RP material to be the optimal choice for the application as the pumice for the cosmetics industry.