Mass shell plots for two models. Pink represents where more than 1% of the available Si has condensed, and indicates the presence of dust. Left: standard model Δφ_p = 0.0, Δφ_s = 0.0; dust forms just behind the shock wave, where the density is high, leading to efficient wind driving. Right: model Δφ_p = 0.4, Δφ_s = 0.0, with poor wind driving. Dust forms when matter is falling back onto the star, in a low-density region, resulting in significantly less matter condensing into dust, and therefore less material is accelerated in the wind.