  In the first paper of this series (Blouin et al. 2018), we presented our
upgraded cool white dwarf atmosphere code. In this second paper, we use our new
models to analyze SDSS J080440.63+223948.6 (J0804+2239), the first DZ star to
show collision-induced absorption (CIA). This object provides a crucial test
for our models, since previous versions of our code were unable to
simultaneously fit the metal absorption lines and the CIA. We find an excellent
fit to both the spectroscopic and photometric data, which further validates the
improved constitutive physics of our models. We also show that the presence of
metal lines allows to lift the degeneracy between high and low hydrogen
abundances that usually affects the fits of white dwarfs with CIA. Finally, we
investigate the potential impact of spectroscopically undetected metals on the
photometric solutions of DC stars.
