I got to play with gas, charcoal, and coal forges at the New England School of Metal Work in Auburn Maine. They make their own charcoal out of scrap wood behind the building. I can tell you that you can work over coal for a long time. You have little time with charcoal. You go through charcoal quick! They bag it up and we were using a lot. The gas forges were cool but I got a lot of scale with the gas. You don't get as much with the coal. I think it smothers the air out around the steel, and it stays cleaner. That's interesting.
