We study the spectral appearance of an evolving post-AGB object by means of two-fluid radiation hydrodynamics (gas and dust) in spherical symmetry. The stellar parameters as well as mass-loss rates are assumed to vary consistently with the stellar model calculations of Blöcker (1989, Diplom Thesis, University of Kiel) for a 3 M⊙ sequence, resulting in a 0.605 M⊙ remnant. The expelled mass is assumed to consist of spherical astronomical silicates with grain radii of 0.1 μm and an initial dust-to-gas mass ratio of 7.5·10−3. For further details on the computational method we refer to Szczerba & Marten (1992, in: Proc. of the ESO/CTIO Workshop, Mass Loss on the AGB and Beyond, La Serena 1992, in press).