The method was chosen because of the proximity of salty waters and the lack of more adequate installations. It is based on Lars Barkman's results on reducing iron with hydrogen, and Rosenberg's method in Copenhagen (practiced by Boërge Brorson Christensen). Hydrogen apparatus was not available; a modified Rosenberg method was adopted, which adds the reduction by carbon oxide in the process of heating. The hydrogen method is faster, but this method does not exclude a hydrogen reduction, later.