True story from when my Dad worked in a body shop.

One of the lads had a hole in his rubber boots. Dad says "Go over to Jim (the welder) and get him to weld them up for you.
The lad trots over to Jim with his rubber boots in hand. Jim say's "Sorry, I don't have any rubber welding rods, go and ask Bill, see if he's got any"

Of course Bill doesn't have any, and he sends him to someone else. So, for about a week the lad goes around trying to find some rubber welding rods.

Eventually, on of the guys gets some old welding rods, knocks what's left of the flux off of them and threads on some rubber from some old electrical wire.

The lad gleefully takes these over top Jim who says "Sorry Son, You need a DC machine for those. This machine is AC."