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At the smelt’s end, the furnace was allowed to cool slightly, then broken open.
The Appearance:
Inside, at the bottom, sat the bloom—a spongy mass of iron, slag, charcoal, and unburned ore all fused together. It was not clean metal but crude mixture requiring extensive further work.
The bloom was removed carefully (it was still extremely hot), placed on a massive stone or iron block, and immediately worked while still hot.
The Hammering:
The smith attacked the bloom with heavy hammer, striking repeatedly, forcefully. Each blow:
- Compacted the spongy iron, making it denser
- Squeezed out slag inclusions
- Broke up remaining charcoal pieces
- Began shaping the mass into workable form
This was brutal work—the bloom weighed 20-40 pounds, the hammer was heavy, the striker had to work while the iron remained hot enough to be malleable. Multiple people might work in rotation, maintaining the relentless hammering until the bloom became consolidated iron bar.
The Reheating:
As the bloom cooled, it became too hard to work. It was thrust back into the forge fire, reheated to cherry-red, then hammered again. This cycle repeated many times—heating, hammering, heating, hammering—gradually transforming spongy bloom into solid iron.
The Yield:
From 100 pounds of ore, perhaps 15-20 pounds of usable iron emerged. The rest was lost as slag, burned away, or remained in too-small pieces to recover. This low yield made iron expensive—not the ore itself (which was abundant) but the labor, fuel, and skill required to transform it.
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