  The luminous Type IIn SN 2010jl shows strong signs of interaction between the
SN ejecta and dense circumstellar material. Dust may be present in the
unshocked ejecta, the cool, dense shell between the shocks in the interaction
region, or in the circumstellar medium. We present and model new optical and
infrared photometry and spectroscopy of SN 2010jl from 82 to 1367 days since
explosion. We evaluate the photometric and spectroscopic evolution using the
radiative transfer codes MOCASSIN and DAMOCLES, respectively. We propose an
interaction scenario and investigate the resulting dust formation scenarios and
dust masses. We find that SN 2010jl has been continuously forming dust based on
the evolution of its infrared emission and optical spectra. There is evidence
for pre-existing dust in the circumstellar medium as well as new dust formation
in the cool, dense shell and/or ejecta. We estimate that 0.005--0.01M$_{\odot}$
of predominantly carbon dust grains has formed in SN 2010jl by ~1400d
post-outburst.
