the observed points superimposed on our theoretical shock model grid. From this, it is immediately apparent that nowhere does the measured iron depletion factor; $\log D_{\rm Fe}$ exceed -0.5. Indeed many of the points are consistent with no depletion at all.

Furthermore, it is clear that the indicated shock velocities in general exceed 200km/s. Thus for most of these the \[\] line ratio can be used to estimate the shock velocity. However, a number of the points lie in the ambiguous region of the / line ratio velocity diagnostic. To the extent to which it is possible, both shock velocities and $\log D_{\rm Fe}$ have been estimated for each cloud from these diagnostic diagrams. The results are given in Tables \[table3\] and \[table4\]. We find a mean shock velocity $\left< v_s \right >$ of 240 km/s, and $\left < \log D_{\rm Fe} \right > = -0.15$. This result agrees very closely with the $\left < \log D_{\rm Fe} \right > = -0.16\pm0.07$ found by @Dopita16 in N49, another bright LMC SNR, and shows that dust has been largely destroyed by the time the recombination zone of the shock has been reached.

A similar analysis was applied to the \[\]$\lambda 5270$/H$\beta$ 