Walloon forge

[2][3] Louis de Geer brought it to Roslagen in Sweden at the beginning of the 17th century, with Walloon blacksmiths.

A V-shaped hearth using charcoal was used to heat up the pig iron bar that was presented to a tuyere that decarbonized it and made it melt and fall in drops that solidified in a pool of slag where the decarburization continued.

It is possible the manganese bonded with the impurities during the oxidation, creating a pretty pure wrought iron.

[7][8] In England, the chafery might use coal or coke, as in this stage the iron is solidified and the contamination remain low.

The blister steel was than purchased by Benjamin Huntsman who melted it in crucibles heated in coke-fired ovens and poured it.