Get the bottle hotter, slower. I would suggest perhaps an oxymapp torch with adjustable mapp tank and oxygen tank valves ($50 from Sears, with tanks - READ INSTRUCTIONS). Just heat it up with the straight mapp flame (maybe with a touch of oxygen, not too much or you'll get a very hot flame), and gradually work the bottle over with the flame slowly until its glowing red almsot white hot, then I dunno what to do, but I like my cutting torch