Tough sanke cleaning

[Telemon]

Hi, I have a used 13.5 US gallon sanke keg that has some mysterious residues caked to the inside. I don't believe it is beer stone as I have managed to remove that with multiple hot PBW washs. I then tried a concentrated malic acid solution (I had some on hand) which didn't do much of anything. I then tried steaming it over a burner for 20 mins which also didn't do anything except maybe cake the residue on further (!?).

There is one ring of yellow-white residue that just won't budge. There's also other mysterious mineral or chemical looking deposits all over the inside. I even tried soda ash, which did nothing.

Is there an acid I could try? Sulfuric?

Thanks,
Ted

 

[HDIr0n]

How long were you soaking them for? I would try something for a long soak time if you don't have a keg cleaner type setup.

 

[rorypayne]

I don't know if you figured this out but coca cola. I know it sounds stupid but it works. I have used it to take everything off everything. Good luck