Food for thought: Some of the old off road two-stroke motorcycles with aluminum engines came from the factory with a flat black paint that was there to help radiate the heat energy from the engine. (see: crazyclimber's comment above.) Looks like that black coating might cut both ways. However, I'm thinking that if there is more heat on the outside of the pan -- the fire -- than there is on the inside -- the cooking food -- that there would be a net gain in heat to the inside. Don't really know S#@t about physics, just a guess!
Here is a cleaning tip that works pretty well. There is a plant that grows here in the U.S. called equisetium, (common name: horsetail) The old pioneer name for this plant was "scouring rush" which says it all. This plant is about a foot to two feet tall, dark green, ridged, and hollow. It is jointed every few inches and can be popped apart and used like a straw. There are no true leaves, it is a very primitive plant. There is a dark band at each joint. It can be seen growing in water, along the margins of streams and ponds. I have seen it on dry ground but very rarely. Now, here is the good part -- The walls of this plant contain silica, (sand). Wad up a handful of these and scrub away. They are abrasive but not overly so, they will not scratch or damage anything. My only problem, passing this on is I don't know if this plant grows in the U.K. Somebody might tell me, I'm curious.
Here is a cleaning tip that works pretty well. There is a plant that grows here in the U.S. called equisetium, (common name: horsetail) The old pioneer name for this plant was "scouring rush" which says it all. This plant is about a foot to two feet tall, dark green, ridged, and hollow. It is jointed every few inches and can be popped apart and used like a straw. There are no true leaves, it is a very primitive plant. There is a dark band at each joint. It can be seen growing in water, along the margins of streams and ponds. I have seen it on dry ground but very rarely. Now, here is the good part -- The walls of this plant contain silica, (sand). Wad up a handful of these and scrub away. They are abrasive but not overly so, they will not scratch or damage anything. My only problem, passing this on is I don't know if this plant grows in the U.K. Somebody might tell me, I'm curious.