A cover is configured for use with a fluid jet device having a surface defining a plurality of orifices formed therein through which a fluid is jetted. The cover includes a cover element movable parallel to the surface between a covered position in which the cover element overlies the orifices and an uncovered position in which the cover is moved to expose the orifices. The cover includes a mounting portion configured to maintain the cover spaced from the surface to define a vapor space region. At least one hinge element operably mounts the cover to the fluid jet device. The hinge element includes a first leg mounted at a free end to a stationary portion of the fluid jet device and a second leg mounted at a free end to the cover portion. The first and second legs are connected to one another by a flexible region such that movement of the legs slides the cover between the covered and exposed positions. The vapor space region maintains a level of fluid vapor concentration around the orifices to reduce the rate of evaporation of the fluid.