  Several mechanisms have been proposed to explain the alignment of grains with
the interstellar magnetic field, including paramagnetic dissipation, radiative
torques, and supersonic gas-grain streaming. These must compete with
disaligning processes, including randomly directed torques arising from
collisions with gas atoms. I describe a novel disalignment mechanism for grains
that have a time-varying electric dipole moment and that drift across the
magnetic field. Depending on the drift speed, this mechanism may yield a much
shorter disalignment timescale than that associated with random gas atom
impacts. For suprathermally rotating grains, the new disaligning process may be
more potent for carbonaceous dust than for silicate dust. This could result in
efficient alignment for silicate grains but poor alignment for carbonaceous
grains.
