An apparatus is disclosed for coating a surface that is movable relative to the apparatus with a layer of metallic particles or particles having a metal-like appearance and reflectivity, the particles adhering more strongly to the surface than to one another. The apparatus comprises at least one spray head for directly or indirectly applying to the surface a fluid stream within which the particles are suspended, a housing surrounding the spray head(s) and defining an interior plenum for confining the fluid stream, the housing having a rim adjacent the surface that is configured to prevent egress of particles from a sealing gap defined between the rim of the housing and the surface to be coated, and a suction source connected to the housing to extract from the plenum the sprayed fluid and particles suspended in the sprayed fluid. In operation, the suction source extracts substantially all particles that are not in direct contact with the surface, so as to leave only a substantially single particle layer adhering to the surface on exiting the apparatus.