Grain size distributions f_i(a) as a function of post-explosion time for the various dust types formed in the homogeneous ejecta of a 15  M_⊙ SN. Bottom-right panel: grain size distribution summed over all dust types, a power law distribution with exponent −3.5 and the MRN power-law distribution (exponent −3.5 and 50 Å <a< 2500 Å) for an equivalent dust mass at day 900 and 2000 post-explosion.