  Infrared (IR) observations of core collapse supernovae (CCSNe) have been used
to infer the mass of dust that has formed in their ejecta. A plot of inferred
dust masses versus supernova (SN) ages shows a trend of increasing dust mass
with time, spanning a few decades of observations. This trend has been
interpreted as evidence for the slow and gradual formation of dust in CCSNe.
Observationally, the trend exhibits a $ t^2$ behavior, exactly what is expected
from an expanding optically thick ejecta. In this case, the observed dust
resides in the infrared (IR)-thin "photosphere" of the ejecta, and constitutes
only a fraction of the total dust mass. We therefore propose that dust
formation proceeds very rapidly, condensing most available refractory elements
within two years after the explosion. At early epochs, only a fraction of the
dust emission escapes the ejecta accounting for the low observed dust mass. The
ejecta's entire dust content is unveiled only a few decades after the
explosion, with the gradual decrease in its IR opacity. Corroborating evidence
for this picture includes the early depletions of refractory elements in the
ejecta of SN1987A and the appearance of a silicate emission band around day 300
in SN~2004et.
