A vapor source for depositing a thin film of polymeric lubricant on a magnetic or MO recording medium comprises an enclosure comprised of at least one thermally conductive material and including a back wall and a front wall spaced apart by at least one sidewall thereby defining a chamber with an interior space, the front wall comprising a plurality of openings forming a vapor diffusion plate with an array of vapor orifices; at least one liquid reservoir within the interior space for containing a vaporizable liquid material; a heater for heating the interior space and forming a vapor of the liquid material; and a shutter device for controlling flow of vapor through the orifices of the vapor diffusion plate, thereby reducing lubricant consumption.