Radial drift speed v_r of particles as a function of the particle size τ_f and solid concentration Z = Σ_solid/ Σ_total. Speed is measured in terms of the sound speed c_s. All solids experience gas drag. Particles of size τ_f ~ 1 experience very rapid drift, which decreases for larger particles. In addition, higher Z forces the gas component to orbit closer to the Keplerian speed, reducing | v_r |. However, in all cases, the drift speed remains high. For reference, for | v_r | = 0.005c_s the particles cross the disk after a few thousand years.