Home made wort chiller ?

I just made a wort chiller and have a question about the copper. This is probably the second time I've soldered something and my copper has turned a black color near the elbows where I solder. I've attached a picture so you could see what I'm talking about. Should I use some kind of cleaner or just buff it with a scotch pad to get rid of the blackness? I'm just worried it would affect the taste of my beer.

I tested it out for leaks and there's none

Do you use starsan? Mix up a double strength batch in a bucket and let the chiller soak for a couple hours. It will come out shiny.

If you don't have Star-San a dilute solution of vinegar and water will also work.

Boil some water with the chiller in it, that should rinse anything off, and give you a chance to test how quickly it cools.

Barkeepers friend and a green scrubbie or a brass wire brush will clean it right up.

Perfectly normal discoloration during soldering. Any of the above for cleaning. A wire brush will also remove any rosin.

Awesome! Thanks guys. I ended up getting some Scotch Brillo cleaning pads. Things shiny as Russian gold!