Making smooth, high quality chocolate needs one final intensive mixing stage after the basic cocoa flavour has already developed through roasting and grinding. In this stage, heavy rollers or blades stir the chocolate mass continuously for hours, sometimes days, at a controlled temperature, driving off sharp, bitter volatile compounds and coating every particle of sugar and cocoa evenly with cocoa butter. This long stirring and mixing step, which gives finished chocolate its silky, melt in the mouth texture, is called conching.