A gasket (1) having a reversibly compressible lower portion (17), and an upper portion (14) having at least one upwardly extending extension, is described. The upper portion (14) of the gasket (1) includes a first (34) and optionally a second (37) upwardly extending extension, each having an exterior surface (43, 55). The first and second extensions of the upper portion each have a vertical center line (49, 58) that resides over (or extends through) an underlying exterior longitudinal groove (73, 76) of the lower portion, such that when the gasket is compressed along its vertical center axis (23) a force (79, 82) is exerted laterally outward along (or through) the exterior surfaces of the upwardly extending extensions. The force exerted laterally outward along the exterior surface of an upwardly extending extension serves to maintain a seal (214, 217) formed by abutment of the exterior surface of the extension with a separate surface (e.g., the upper edge (190, 193) of a channel (121) in which the gasket resides) while the gasket is reversibly compressed along its vertical center axis. Also described is a method of preparing a coated molded article (223) in a mold apparatus (8) that includes the gasket of the present invention.