Crushing and Grading Charcoal

Lump charcoal comes in pieces from fingertip to fist size. A forge or a smelting furnace burns evenly only on pieces of one size, so the lumps are broken in a sack and sieved into grades. Bloomery smelters break it to about 2.5 cm and sift the fines out through a 1 cm (3/8 inch) mesh; the fines are kept for the furnace base, for insulation or for the garden. Weigh each grade: the split tells you how much of a sack is usable at your size.