  In our study we investigate the behaviour of the net force (NF) emerging
between an ellipsoidal particle and a thick plate (slab), when the interaction
takes place in a near critical fluid medium with account for the omnipresent
van der Waals forces (vdWF). Here we consider the case of complete wetting of
the objects surfaces by the medium, due to strong adsorbing local surface
potentials, exerted by thin solid coating films. The influence of the bulk
inner regions of the particle and the slab on the constituents of the fluid
results in long-ranged competing dispersion potentials. As a consequence from
the critical fluctuations of the medium, the system experiences an additional
effective interaction, traditionally termed critical Casimir force (CCF). The
forces of interest are evaluated numerically from integral expressions obtained
utilizing general scaling arguments and mean-field type calculations in
combination with the so-called "surface integration approach" (SIA). Within the
scenario considered here, this technique is applicable if one has knowledge of
the forces between two parallel semi-infinite plates, confining in between some
fluctuating fluid medium characterized by its temperature $T$ and chemical
potential $\mu$. It is demonstrated that for a suitable set of particle-fluid,
slab-fluid, and fluid-fluid coupling parameters the competition between the
effects due to the coatings and the core regions of the objects result, when
one changes $T$ or $\mu$, in {\it sign change} of the NF acting between the
ellipsoid and the slab.
