  Radiation which has a quadrupole component of anisotropy, can get polarized
by Thomson scattering from charged particles. In the cosmological context, the
microwave background photons develop significant quadrupole anisotropy as they
free stream away from the the epoch of standard recombination. Reionization in
the post recombination era can provide free electrons to Thomson scatter the
incident anisotropic $CMBR$ photons. We compute the resulting polarisation
anisotropy on small (arc-minute) angular scales. We look for significant
non-linear contributions, as in the case of Vishniac effect in temperature
anisotropy, due to the coupling of small-scale electron density fluctuations,
at the new last scattering surface, and the temperature quadrupole. We show
that, while, in cold dark matter type models, this does not lead to very
significant signals ($\sim 0.02 - 0.04 \mu K$), a larger small angular scale
polarization anisotropy, ($\sim 0.1 - 0.5\mu K$), can result in isocurvature
type models.
