Author Topic: star san turned the metal on keg QDs black  (Read 1501 times)

Offline passlaku

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star san turned the metal on keg QDs black
« on: February 08, 2012, 08:16:55 PM »
I left some of my qds soaking in Star San overnight and found the metal on the thread colored black.  Why did this happen?  I think I may be able to buff out the black stain but it is very weird.

Offline rbclay

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Re: star san turned the metal on keg QDs black
« Reply #1 on: February 08, 2012, 08:35:41 PM »
i've done that too. no big deal. can't tell you exactly why, but likely because it is an acid based solution. it just reminded me that Star San only needs a 3 minute contact time to sanitize. soaking metal overnight turns stuff black. scrub it. some of it will come off.
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Offline morticaixavier

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Re: star san turned the metal on keg QDs black
« Reply #2 on: February 08, 2012, 09:03:51 PM »
I once discovered that idophor turns silver purple. :o it was my wedding ring and my wife was much happier when it eventually wore off.

Offline euge

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Re: star san turned the metal on keg QDs black
« Reply #3 on: February 08, 2012, 10:17:06 PM »
Why are you soaking over night in starsan?
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline brewmichigan

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Re: star san turned the metal on keg QDs black
« Reply #4 on: February 09, 2012, 07:48:05 AM »
Why are you soaking over night in starsan?

When I forget I'm doing it.  :P
Mike --- Flint, Michigan

Offline passlaku

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Re: star san turned the metal on keg QDs black
« Reply #5 on: February 09, 2012, 10:01:22 AM »
Why are you soaking over night in starsan?

When I forget I'm doing it.  :P

+1

I totally forgot that I had left them in the StarSan bucket.

Offline hamiltont

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Re: star san turned the metal on keg QDs black
« Reply #6 on: February 09, 2012, 12:23:25 PM »
It happens...  Happens even more often the older you get. Just ask me what vinyl tubing looks like after a month in starsan...  :o No, never mind. I'll tell ya. It's like a snake that just crawled out of a swamp. Slimy & gooey.... The only good thing was it was really sanitized...  ::)
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Offline richardt

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Re: star san turned the metal on keg QDs black
« Reply #7 on: February 09, 2012, 12:37:09 PM »
I got a vinyl transfer hose that's been soaking in starsan for months--what was clear is now opaque and whiter than white.

Yes, I still use it for transfers w/o problems.




Offline thomasbarnes

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Re: star san turned the metal on keg QDs black
« Reply #8 on: February 09, 2012, 01:29:51 PM »
I left some of my qds soaking in Star San overnight and found the metal on the thread colored black.  Why did this happen?  I think I may be able to buff out the black stain but it is very weird.

My ignorant guess is that the metal in the threads was a bit worn, so the underlying metal was exposed. Star San is acidic (~50% phosphoric acid), so it corroded the metal. The black stuff is some variety of metal oxide.

Unless the oxide looks like it's coming off, or is in direct contact with your beer or wort, I wouldn't mess with it.

Offline dean_palmer

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Re: star san turned the metal on keg QDs black
« Reply #9 on: February 09, 2012, 01:55:28 PM »
I've got some disconnects that are really old and have had the plating on the threads completely eaten away by Star San I'm guessing. I'm sure I've forgotten them in the bucket a few times for hours or overnight, but because those threads don't contact the beer it doesn't really matter. I should take some pics. I'm just impressed they have lasted this long without me breaking them or something :-)