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I haven't had the chance to brew in about two years and I've been storing my copper wort chiller in a storage locker for most of that time. Upon moving and retrieving it yesterday, it's got some really interesting coloration on it. The bronzed color is worn off in little splotches and circles here and there. I'm not sure what caused it (be it storage with too much access to the air or improper cleaning the only time I used it).

I have a couple of questions:

  1. Is it still good?
  2. If it is, do I just want to clean it as outlined here or will I need to do something special because of that? cleaning copper
  3. Will these spots, where it almost looks oxidized or as though paint has chipped off, cause any potential problems with brewing or flavor?

Thanks a bunch!

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3 Answers 3

up vote 1 down vote accepted

As long as it isn't rusted and/or leaking, you're probably fine. If it were me, I'd take some polish to it and make sure to rinse it thoroughly afterwards just to be certain. You may not have to, but my perfectionism would scream at me for any mistakes in the flavor of the beer, even if it had nothing to do with the chiller.
I vividly remember having to spend hours polishing brass in the military with the previously linked Brasso, which was seemingly capable of removing any tarnish the metal could throw at me, so I'd imagine it could gnaw right through any oxidized blotches you might have on your chiller.

Like I said, just make sure you rinse it after you polish it, probably would help to run it over with a wet rag just to make sure, but it should do the job perfectly.

EDIT: Just realized copper doesn't rust, so you're safe in that regard.

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Agreed, I tend to be a perfectionist anyhow. It's definitely got some discoloration, which is what had me worried. There are bits of it that have turned a little rainbow-y or silver. You think they're still just oxidized blotches? That sounds good, though, thank you so much! –  Drew Copenhaver Jul 22 '13 at 18:05
    
I'd certainly say it's either oxidized or moisture causing it to slightly erode (nothing serious), but since it hasn't been in continual contact with liquid to cause any serious corrosion, you should be fine. This of course is unless it has gone all statue of liberty green on you, in which case I would advise you to get a new one. A little polish, some elbow grease, and a thorough rinse, and you'll be good. –  Scott Jul 22 '13 at 18:47
    
Excellent, yes, I'm not seeing any green or corrosion, just a bit of discoloration. Thank you so much for your advice! –  Drew Copenhaver Jul 22 '13 at 19:56
    
Welcome back to the hobby. –  Scott Jul 22 '13 at 20:33
    
Barkeeper's friend also works great for cleaning copper (as well as stainless steel and a lot of other stuff). It's cheap and rinses of easily. –  paul Jul 30 '13 at 18:57

You don't want to clean a copper chiller so it is shiny - if you remove the dull color (stable oxide), the metal is more likely to react and form the toxic blue-green oxide (verdigris).

http://byo.com/stories/projects-and-equipment/item/1144-metallurgy-for-homebrewers

Copper is relatively inert to both wort and beer. With regular use, it will build up a stable oxide layer (dull copper color) that will protect it from any further interaction with the wort. Only minimal cleaning to remove surface grime, hop bits and wort protein is necessary. There is no need to clean copper shiny-bright after every use or before contact with your wort. It is better if the copper is allowed to form a dull copper finish with use.

However, you need to be aware that copper can develop a toxic blue-green oxide called verdigris. Verdigris includes several chemical compounds — cupric acetate, copper sulfate, cupric chloride, etc. — and these blue-green compounds should not be allowed to contact your beer or any other food item because they are readily soluble in weakly acidic solutions (like beer), and can lead to copper poisoning (i.e., nausea, vomiting). To clean heavy oxidation (black) and verdigris, use vinegar or oxalic acid-based cleansers like Revereware Copper and Stainless Steel cleanser.

For regular cleaning of copper and brass, unscented dish detergent or sodium percarbonate-based cleaners are preferred. Cleaning and sanitizing copper wort chillers with bleach solutions is not recommended. Oxidizers like bleach and hydrogen peroxide quickly cause copper and brass to blacken; these oxides do not protect the surface from further corrosion, and are quickly dissolved by the acidic wort. Copper and other trace metals are beneficial nutrients for yeast, but the amounts that are dissolved from non-passive oxides can be detrimental to the batch.

Copper counterflow wort chillers should not be stored full of sanitizer or water. Any biological deposits can lead to corrosion in both water or sanitizer. Copper should be rinsed thoroughly with clean water and allowed to drain before storage.

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Good find! This is more deserving of the chosen answer. –  Scott Jul 29 '13 at 14:30

After every 10 or so brews, I soak mine in powdered brewery wash (PBW), goes in with a rainbow of colors comes out looking like new. Plus, no elbow grease required.

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Ooo, good to know, thanks! –  Drew Copenhaver Jul 23 '13 at 12:32

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