Does the warning label say that this can happen? Definitely. Was the welder being careless? Sort of, but not really. When you use these chemicals all the time, they become as commonplace as a wrench or screwdriver. If you spend much time in a shop, carburetor cleaner and brake cleaner become everyday fixes for a variety of problems, just like any other tool. You absolutely will start to take them for granted. And that is exactly why this man's story matters.