The problem with charcoal is that it takes a lot of wood to make charcoal. The use of charcoal in the preindustrial era lead to the deforestation of Europe and much of the east coat of the United States. Coal was introduced as an alternative fuel in the 1800's and continued as the main fuel well past the turn of the century. Coal has many problems and is not an ideal fuel for working steel. A modern alternative is propane.
Propane is clean burning, hot and controllable.
I use propane forges exclusively for my welding, forging and heat treating operations. I realized that building the universal forge, one that was perfect for welding, forging, heat treating, and general forging was an impossible task, so in my shop I have many forges each built for each operation. They are all built off one basic design however and on this page I will lay out the design and construction of a basic forge. The author specifically disclaims any responsibility or liability for any damages or injuries incurred as a result of the use of any information published herein. Inswool-HP blanket, a 2400F ceramic fiber insulation.