Brown, crusty scuzz inside of keg I just cut open

Hey everyone,

So I cut the top off this Sanke I want to use as an HLT, and that went well. Drilling and adding a ball valve also went well. My problem is that the inside of the keg has a brown, crusty residue coating it. It's hard-- my fingernail doesn't scratch it at all-- and rough, maybe the feeling of a fine emery cloth.

Since I had the angle grinder out, I put on a fine grit pad and hit the inside with that; there was a ton of white-ish powder spewed into the air, but I got down to clean metal without a problem on the big flat spots. But there are all sorts of crevices where I can't get the grinder, and I can't lay the grinder down flat enough to get to the very bottom.

Is this beerstone of some sort? Is it normal? Should I worry about getting every last speck out before I use it?

I searched the forums, but variations on "brown crusty scuzz" don't get you many results... hot Oxy-Clean and a green scotch-brite didn't phase it. I'm thinking I'm down to lots of elbow grease and some fine grit sandpaper... ?

Thanks for any insight you have.

Ick!
That one has been sitting a while, a looong while.
Scrub scrub scrub and I would be very careful about breathing that schtuff.
I recently cracked open a two year old keg and damn, the remnants smelt drinkable.

If it's mineral deposits from water (i.e calcium and/or magnesium carbonates), try some vinegar, the acetic acid should take care of it.

Now, if it's true beer stone (calcium oxalate), then you're looking at an entirely different puppy. This is because calcuim oxalate is not very soluble in any traditional household (and "safe") solvents. Concentrated mineral acids (like nitric acid) can be effective, but probably should not be used by the average Joe. There is one thing that I might suggest, although it's somewhat risky, depending on your situation.

Calcium oxalate decomposes to calcium carbonate at around 500C (CaC2O4----> CaCO3 + CO @ ~500C), and the resultant calcium carbonate is soluble in vinegar. Simply convert the calcium oxalate to calcium carbonate and use a mild acetic acid wash to remove the remaining film. Problem is, how do you get to 500C controlled? A blowtorch might work, however, if this is an aluminum keg, aluminum melts at 660C or so. You must make sure your flame temp is >500C but < 660C - kinda hard to do in the basement. Just insert the keg into a kiln set at 575C for an hour and you're set. Piece of cake! This is obviously a difficult solution.

EDTA has been a proven method to removing beer stone, but I'm not sure if you can/want to get the EDTA and/or put up with its nasty fishy smell.

Phosphoric acid may be useful, but again, there is some risk when using acids if you don't know what you're doing. Commercial, ice machine places might be a place to get phosphoric acid.

My best advice is to try using a small dental pick or similar device to manually remove it. Tons of work, but is definitely the safest approach.

Whatever you do, make sure your safety is taken care of first. Chemicals are a blessing if use correctly and a nightmare if used incorrectly.

Just a thought might try taking it getting it soda blasted ,Soda is safe Gurantee (Justin Wilson guarantee)be clean

brewtus_ said:

If it's mineral deposits from water (i.e calcium and/or magnesium carbonates), try some vinegar, the acetic acid should take care of it.

Click to expand...

I will give this a shot first as it sounds like the easiest with least work. If it doesn't work, no loss.

brewtus_ said:

Now, if it's true beer stone (calcium oxalate), then you're looking at an entirely different puppy.

Click to expand...

After reading that, I think I'll stick with abrasives and a respirator... the grinder got rid of it just fine, so it's a matter of either a Dremel or sandpaper and elbow grease at this point.

RDatsun said:

Just a thought might try taking it getting it soda blasted ,Soda is safe Gurantee (Justin Wilson guarantee)be clean

Click to expand...

Hm, I wonder if my siphon-feed sandblaster will pick up something soft like walnut shells or pumice. I've got a ton of silica sand but I'm not sure I want to do that to it...

I suppose I could just leave it and not worry, since I'm only heating water in it, but ugh. Thanks, guys.