  We study phase separation in two dimensions in the scaling limit below
criticality. The general form of the magnetization profile as the volume goes
to infinity is determined exactly within the field theoretical framework which
explicitly takes into account the topological nature of the elementary
excitations. The result known for the Ising model from its lattice solution is
recovered as a particular case. In the asymptotic infrared limit the interface
behaves as a simple curve characterized by a gaussian passage probability
density. The leading deviation, due to branching, from this behavior is also
derived and its coefficient is determined for the Potts model. As a byproduct,
for random percolation we obtain the asymptotic density profile of a spanning
cluster conditioned to touch only the left half of the boundary.
