Rate of cooling by the principal molecular coolants, H₂ (mauve), H₂O (green), CO (blue) and OH (red) for V_s = 40 km s^-1 and b = 2 for model M1 (left panel) and M2/M3 (right panel), which are shown together because the presence of SiO in grain mantles does not affect the cooling of the shock wave. Note the different distance intervals on the x-axes.