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When the smelt was judged complete, the furnace was allowed to cool slightly, then broken open to retrieve the bloom. This was destructive process—the clay walls were smashed away, the contents dumped out, the still-hot materials sorted to separate iron from slag and unprocessed ore.
The bloom itself was irregularly shaped mass of iron mixed with slag, weighing perhaps twenty pounds though size varied. It was not the shining metal of final products but dark, rough, spongy material requiring extensive further work. But it was iron—the valuable metal extracted from worthless bog mud, the achievement that justified the entire arduous process.
The bloom was usually worked immediately while still hot, the smith beating it with hammer to consolidate the iron and drive out trapped slag. This initial working was brutal—repeated heavy blows, reheating in forge fire, more hammering. Slowly the bloom was transformed from spongy mass into dense metal bar that could be stored or further worked into tools and weapons.
The yield was modest—perhaps half the ore’s weight emerged as usable iron, the rest lost to slag or remaining unreduced in the debris. But this was acceptable return for accessible ore and local labor. The alternative—importing iron from distant sources—was more expensive and less reliable. The bog smelting made communities self-sufficient in most critical material, independent of trade networks that might be disrupted by war or politics.
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