The pickle pot
It's got a cool name, doesn't it?
What on earth is this goofy contraption? I'm sure you're asking yourself that right now. Well, if the solder gods have smiled on my and I haven't melted the shit out of a piece I've labored for hours on, it goes in the pickle pot. The pickle is a strong acid that eats away all the black oxides that form on the metal once you've soldered it. A couple of minutes in the pickle and the piece is shiny and new.
Usually you use really nasty chemicals as your pickle, but I found out that you can use citric acid instead and it works pretty well. It takes longer, but now I'm not breathing in nasty nasty fumes. There are enough nasty chemicals in the world, no need to add more.