Originally Posted by Pike Bishop
FWIW, I would avoid using Alumaweld (zinc) in an aluminum boat or an aluminum lower unit that spends any significant time in the water because you'll get a galvanic corrosion situation where the zinc will eventually disappear ... just like a zinc anode.
You may be correct in regards to salt water, but I live between 2 rivers and back in the 80's when I was doing it for a living I repaired a ton of broken props with this rod. And a propane torch most of the time.
As mentioned, clean the metal (I used a file mostly) and use a SS brush while you are heating it. I never used flux but I must have tried a few back then, and if it had made a difference I'd have kept using it.
One last thing- using a decent propane torch makes a HUGE difference! You owe it to yourself to buy one of these:
It pumps out heat, and is auto start and stop, just squeeze the button for fire, and let go when you want the fire to stop. Get the one like this one with a variable flame, it gives you a bit more flexibility than the fixed flame model does.