Kinda stupid question time, probably… I’m kinda slowly brushing up on my frame-building knowledge after many years away from it. I don’t remember what I don’t know about it all. I’m currently stuck on: why oxy-acetylene/oxy-propane, and not just air-acetylene? Obviously the answer is temperature, but I feel like there must be some more to it than that. Controllability? Obviously the answer is that pure-oxygen flames are superior, because that’s what everyone uses. I’m just curious why?

I’m asking partly because I have an air-acetylene Turbo Torch for plumbing (copper and brass mostly, sometimes some steel), and it seems to get plenty hot. 5500° F ish? And it’s a big, brutish flame that seems to me would be great for lugs, whereby one could get a whole whack of metal up to temp at once. But I know there’s something wrong about this idea, because no one does it. (I’m smart enough to know I don’t have some kind of solution that no one else has ever thought of. ;)) But…why?

Thanks, sages.