A Walloon forge (or Walloon process) is a type of finery forge that decarbonizes pig iron into wrought iron.
The process was conceived in the Liège region, and from there extended to France, then England around the end of the 15th century. Louis de Geer brought it to Roslagen in Sweden at the beginning of the 17th century, with Walloon blacksmiths.
The Walloon process spread to Sweden in the Uppland province north of Stockholm, where it was used to produce a specific kind of wrought iron called oregrounds iron.