14 is of greater mass than lower portion 16 to keep the plug lying horizontal on a flat surface even with residual caulking or adhesive material caked on the scoring edges as shown in fig5 of the 39 597 patent when plug 12 is rotationally inserted within the dispensing aperture of a distally tapering nozzle made of a soft plastic at least one edge partially scores the nozzle interior surface creating a groove although the edge points 19 penetrate the surface a small gap exists between each adjacent pair of penetrating edges which meet in a u201c v u201d shaped vertex and the surface such gaps which reform when the plug after having been rotationally removed is reinserted fill with residual material to create an air tight seal fig2 shows a plug 50 according to the present invention which superficially appears very similar to plug 12 plug 50 includes a knurled upper portion 52 a conically tapering lower portion 54 with a multiplicity of successively contiguous circumferential scoring edges 56 and a rounded tip 58 disposed between and rigidly attached to upper and lower portions 52 54 is a circumferential skirt 60 having a polygonal plurality of generally planar edge segments 62 which prevent the.