Emergent radiation from the same model as in the top row in Fig. 8, but after switching off the magnetic field. This figure demonstrates that even though the maximum optical thickness of the model is only around τ ≈ 1, the symmetry breaking effects due to 3D radiative transfer play a significant role and the Stokes U signal is far from zero. Neglecting 3D radiative transfer could lead to serious errors in the interpretation of the observations.