Spitzer mid-IR observations of core-collapse supernovae have revealed dust formation to be common during the first 1000 days after explosion, while Herschel far-IR observations of supernova remnants such as Cassiopeia A, SN 1987A and the Crab Nebula have measured up to 0.1-0.5 solar masses of cool dust to be present in their ejecta (Barlow et al. 2010, Matsuura et al. 2011, Gomez et al. 2012, Owen & Barlow 2015, Wesson et al. 2015). These estimates are based on fitting the observed infrared continuum emission. However, the completion of the Herschel mission means that there will now be a long wait for comparable or better spaceborne thermal infrared facilities to become available.

The absorption of optical or near-IR radiation by newly-formed dust within the ejecta of supernovae can result in an asymmetry between the red and blue shifted components, with the redwards emission from the far side of the ejecta undergoing greater absorption (Lucy et al. 1989). Such red-blue asymmetries are frequently observed in the late-time (T>400d) spectra of supernova ejecta and there is a large database of such observations available. We present here a new Monte Carlo code that models factors affecting the red-blue asymmetry, including smooth or clumped dust distributions, in order to assess the utility of line profile fitting for quantifying the masses of dust formed in supernova ejecta. We also present some examples of preliminary line profile fits for SN1987A.