My current boss, has been a brewer for many a year, occasionally drops a fascinating fact into the conversation. He started out working for Courage, so Imperial Russian Stout occasionally crops up, and I'm pleased to say that last week the mystery of black malt in the copper was solved.
For those of you unfamiliar with brewing Imperial Russian Stout the instructions tell you to add black malt to the copper (kettle) two hours into the three hour boil. Nowadays it might be common for hops to be added at just about any stage of brewing but having malt anywhere but the mash tun is decidedly odd. As indeed my boss said when he talked about it. He couldn't work out why until he realised that the malt in the copper acted as an abrasive agent to scrub off some of the crud that builds up on the heating element during a long boil of a strong wort so restoring some efficiency.
I for one have been able to sleep easier in my bed knowing this. I wonder if he ever brewed an AK in his Courage days?