 Even when playing a bare aluminium disc with a modern lightweight magnetic cartridge, a hard stylus that does not correctly fit the contour of the groove will score its surface and tend to skip and repeat, damaging the disc as well as degrading the quality of the recovered audio.Because the blunt recording stylus typically bore down on the aluminum at a substantial angle, it produced a disproportionately shallow groove, so that optimum playback with modern equipment requires a custom stylus with an unusually large tip radius.In 1934, the Pyral Company in France and the Presto Recording Corporation in the United States independently created the so-called acetate disc by coating a layer of nitrocellulose lacquer onto the aluminum, which now served only as a rigid support.