Folding and welding an iron bloom

Donald B. Wagner
17 October 2022

Rowan The sickle The original artefact
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At the Caherconnell Furnace Festival, 27–28 August 2022, it was fascinating to watch Rowan Taylor, heritage blacksmith, make this reproduction of an 11th-century iron sickle (or billhook, or brush-hook) from bloomery iron. You can find out more about Rowan’s work, and about this piece, on his two Facebook pages (1, 2), or on YouTube, or on the website for his Saxon Forge, or by googling him.

On this page I have concentrated on a single aspect of the making of the sickle: the reworking of an iron bloom by repeated folding and welding in order to break up and spread out the slag inclusions in the bloom.

A typical bloom after this treatment
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Consolidating a bloom
Simon Kotowicz

All pre-Bessemer wrought iron (bloomery iron, fined iron, puddled iron) contains slag inclusions. As can be seen in the film here on the left, when the spongy ‘bloom’ is taken red-hot from the furnace, it is hammered to squeeze out as much of the molten slag as possible: first gently with a broad wooden hammer, then more powerfully with sledge hammers. The result is a rough bar for the blacksmith to work with. After this it is impossible to remove any more slag, but the influence of the inclusions on the quality of the iron can be reduced by further processing.

The first attempt
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Rowan was not accustomed to working with bloomery iron directly from the furnace, and his first attempt to make the sickle was a failure. As you see here, the slag inclusions caused cracks in the iron. On his second – successful – attempt, he first broke up the inclusions by repeated folding and welding – in principle the same sort of operation as when a baker kneads his dough, but with a less tractable material. He folded the bar ten times; in the film below I have captured the last three folds. Note that he used a power hammer in processes where a pre-modern blacksmith would have had one or two assistants wielding sledge hammers.

 

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