  Considering the hydrodynamical limit of some interacting particle systems
leads to hyperbolic differential equation for the conserved quantities, e.g.
the inviscid Burgers equation for the simple exclusion process. The physical
solutions of these partial differential equations develop discontinuities,
called shocks. The microscopic structure of these shocks is of much interest
and far from being well understood. We introduce a domain growth model in which
we find a stationary (in time) product measure for the model, as seen from a
defect tracer or second class particle, travelling with the shock. We also show
that under some natural assumptions valid for a wider class of domain growth
models, no other model has stationary product measure as seen from the moving
defect tracer.
