  We discuss the central role that dust condensation plays in shaping the
observational appearance of outflows from coalescing binary systems. As
binaries begin to coalesce, they shock-heat and expel material into their
surroundings. Depending on the properties of the merging system, this material
can expand to the point where molecules and dust form, dramatically increasing
the gas opacity. We use the existing population of Luminous Red Novae (LRNe) to
constrain the thermodynamics of these ejecta, then apply our findings to the
progressive obscuration of merging systems in the lead in to their coalescence.
Compact progenitor stars near the main sequence or in the Hertzsprung gap along
with massive progenitor stars have sufficiently hot circumstellar material to
remain unobscured by dust. By contrast, more extended, low-mass giants should
become completely optically obscured by dust formation in the circumbinary
environment. We predict that 30--50\% of stellar coalescence transients for
solar-mass stars will be dusty, infrared-luminous sources. Of these, the
optical transients may selectively trace complete merger outcomes while the
infrared transients trace common envelope ejection outcomes.
