So the keg I got and converted into a keggle had apparently been sitting empty for quite some time. It had a major layer of some seriously stubborn beer grime. I had to fill it with the oxy cleaner for a couple hours and use a scotch-brite just to get the junk off the walls. Even then, I still couldn't get the layer of junk off the bottom of the keg. I have it soaking with plain water and a little dish detergent overnight and will attack it again tonight.
That said, I thought the walls were clean, they're now smooth and look good, but I noticed when I rubbed my fingers across them, I'd get this black residue on them. I thought that odd and to check took a paper towel and wiped it over the walls and also got some sort of black residue.
Anyone know what this is and how I get rid of it? Anyone have other suggestions for getting that amazingly impenetrable layer of beer grime on the bottom of the keg off?
I know starsan isn't good for stainless... but i was thinking like maybe just 20 minutes on the bottom of the keg would eat through that grime layer. I don't want to cause any damage though.