Blast Burden

Prepared blast-furnace charge: iron ore, flux (limestone) and coke mixed in set proportions. Fed to the furnace through the reinforced hopper.

The Burdenmaker is the only source of Blast Burden, dropping a whole batch, wide hopper and narrow hopper together, the moment its gate opens; the ore and lime loaded into both hoppers are exactly what the batch spends, and both ranges clear the instant the gate opens. Its flux fraction decides its grade - 0.03 itself still reads under-fluxed, standard runs above it up to 0.08 inclusive, over-fluxed above that - and that grade, not the fuel charged alongside it, is the only quality the item itself carries. See Ore handling and burden.