Just noticed some heavy black oxidation marks AND some blue-green verdigris (toxic, yum!) on my copper immersion chiller. Was planning on boiling it in some distilled white vinegar and water solution. I understand that this will remove the oxidative layer on the surface of the copper making it nice and shiny. Two questions:

1. Does anyone know what ratio to use for the vinegar/water solution?

2. How do I get that nice oxidative layer back on my chiller before using it in my wort imparting a metallic taste to my next brew?
( I have read that 350F in an oven for 10 minutes after cleaning it will help to build up that good layer again...is this true?)

http://www.howtobrew.com/section1/chapter2-2-2.html

I wouldn't worry about part 2.

I would think that a soak in an acid sanitizer like Star San would work almost as well as boiling it in vinegar. It might be cheaper and probably wouldn't smell up the house as much. That chapter from How to Brew that Spider posted recommends using it to clean copper. I use my old Star San solution to shine up my copper saucepan.

You want to make sure you get all that green shit off.

Ended up boiling it in a quick water/vinegar solution for 5 minutes. Came out nice and shiny. Noticed that the dullness of the copper (oxidized layer) has returned this morning along with what appears to be some "oily" sheen marks that do not wipe away. Hope those are okay....

I use the same mix I use for the monthly coffee machine cleaning, 1/3 distilled white vinegar, 2/3 distilled water.

The outer layer of copper takes less than a second to oxidize. It's a real pain in the ass if you're trying to build a radio antenna with it or trying to get solder to stick to it for any other reason. That tiny bit of oxidation isn't going to hurt your brew however. The colorful shit, however....