The Walloon method conquered Sweden in the 17th century

The Walloon forge is a refining process invented in the Liège region to transform cast iron into wrought iron. Louis de Geer exported it at the beginning of the 17th century to Roslagen in Sweden by having Walloon blacksmiths work there. This technique allowed for the production of a specific iron named vallonjärn to distinguish it from the then-dominant Germanic method.