The present invention relates to masking techniques and apparatuses, and in particular, to a method and apparatus for masking a flexible substrate to be coated with one or more material layers. The method involves flexing a substrate to provide a curved surface and providing a flexible sheet on the curved surface to properly apply a coating on the surface of the substrate. The apparatus includes a substrate and a flexible sheet. An elastic material, such as a spring pin, or an off-axis roll-down bar may be used to create the tension used to flex the substrate and or flexible sheet.