Yep. That’s the gunk that was sitting on my elements in my brewkettle.
A good 30 minute scrub later and we now have:
Better. The elements are still scorched black, probably something due to the Ph of the wort that it’s boiling, but at least there’s no gunk on them anymore.
This could possible be the cause of my off flavours, we’ll have to see what happens.
Either way, I think it’s a good idea to use this as an excuse to get some low density elements in there and make cleaning them part of my regular practice.