We propose polarimetric mapping of the Crab Nebula for the spring launch
 with ISOCAM in the 12-18 and 5-8.5 micron bands. This will enable separate
 colour maps to be derived for the synchrotron and thermal (dust/lines)
 components of the emission. The distribution of synchrotron colours will
 elucidate the nature of the spectral break in the MIR. If the break is due to
 synchrotron losses, we expect to see a reddening towards the edges of the
 nebula. If it is intrinsic to the injected spectrum, we expect to see no
 radial colour trends accompanying the spectral break in the spatially
 integrated flux density.