Eh, looks more like soldering than welding. I would trust it to help a leaking rivet, but don't know that I would trust it to fix a crack. I'm not sure how strong it would be considering the "working temperature" of it is nearly 500* less than the melting point of aluminum. Looks like it would just melt into the crack and not really bond it. As far as rivets go, I'd still buck the rivet before I used it. What are you trying to fix? Might just want to go with JB Weld, or a more permanent solution like Mig or Tig welding. There may be some guys on the board that have used something similar and have more real input, but that's my .02