Measured continuum flux densities at 3 mm (at ν ≈ ν_CO(7−6)) and 1 mm (at ν ≈ ν_[CII]). The expected flux density ratios for modified black body templates with different temperatures T_d and opacity at the [C II] frequency, corrected for the CMB for a source at redshift z = 6, are shown for comparison. Our measurements, color-coded by the IR luminosity of the quasars, are generally consistent with T_d = 47 K and τ_1900 GHz = 0.2, or T_d = 60 K and τ_1900 GHz = 1. The former template is adopted in our analysis when computing IR luminosities and dust masses.