Near-infrared spectroscopy of two IRAS sources, and 18405A)448, whose LRS spectra suggested the presence of carbonaceous dust, confirms that the former is a late-type Wolf-Rayet (WC8-9) star and shows that the latter is not. Together with new red spectroscopy, our data for IRAS 18405A)448 show H I (Hα and Pa6-16), O I excited by the Lyβ fluorescence mechanism, Fe II, [S III] and [O II]. This shows that IRAS 18405-0448 is similar to luminous emission-line objects like LkHα 101 or η Car. The reddening from the continuum and Paschen decrement is found to be E(B - V) = 5.5±0.5 and that from the O I lines E(B - V) ≥ 4.5. It is suggested that this extinction is mostly circumstellar and that the corresponding absorption in the `silicates' feature can account for the IRAS LRS spectral shape. New photometry of IRAS indicates variability in the dust luminosity on a time-scale ∼1.4 yr, possibly caused by variation in the dust condensation rate.