Radiative blast waves can be created by focusing intense laser pulses into highly absorbing clustered gases. By considering the plasma conditions these shocks can be categorized as optically thin radiative shocks, a regime of particular interest for laboratory astrophysics experiments. A periodic spatial modulation is introduced to the shock front in order to investigate instability and shock collisions. Hydrodynamic simulations are presented which are in qualitative agreement with the experimental results. A technique to perform a single shot measurement of the entire shock trajectory and the possibility to detect oscillations in the shock velocity is discussed. © 2009 Elsevier B.V.