  We study the effects of an oscillating axion field on the pressure between
two metallic plates. We consider the situation where a magnetic field parallel
to the plates is present and show that the electric field induced by the
coupling of the axion to photons leads to resonances. When the boundary plates
are perfect conductors, the resonances are infinitely thin whilst they are
broadened when the conductivity of the boundary plates is taken into account.
The resonances take place at the tower of distances close to dn = (2n+1){\pi}/m
where m is the axion mass and have a finite width and height depending on the
conductivity. The resulting resonant pressure on the plate depends on the
induced polarisation at the surface of the plates. We investigate the reach of
future Casimir experiments in terms of the axion mass and the conductivity of
the boundary plates. We find that for large enough conductivities, the
axion-induced pressure could be larger than the quantum Casimir effect between
the plates.
