Observed (black circles) and J14 model optical pseudo-bolometric lightcurves between days 100 and 500 normalized to the radioactive decay chain luminosity of 0.075 M_⊙ of ⁵⁶Ni. The preferred model (12F, blue solid line), model 12C (blue short-dashed line) and model 12E (blue long-dashed line), which differ only in the optical depth (12F, 0.44; 12C, 0.25; 12E, 0) and temperature of the dust, are shown together with model 12B (red short-dashed line), which differs from model 12C only in the positron trapping (12C, local; 12B, non-local).