I'm going to keep using rubber cement because I already have a big jar and have used it successfully to patch dozens of punctures, but this thread has piqued my curiosity. After a bit of internet searching, I have not been able to find a definitive description of the difference between vulcanizing fluid and rubber cement, just people in online forums like this one claiming that they are different. I'm not claiming that they aren't different, I just can't figure out what it is about them that is different. The MSDS for Park Vulcanizing fluid actually lists the trade name as Rubber Cement. The Rema MSDS calls it vulcanizing fluid. Here's the MSDS for Elmers. I'm not a chemist, but as far as I can tell the vulcanizing fluids use naptha as a solvent where Elmer's uses alcohol. Is that the difference that causes the vulcanization? Seems like there should be more to it than that.