| Summary: | This thesis studies Finnish Early Iron Age stone box furnaces used for smelting iron through experimental archaeology. Six archaeological sites have been found in eastern and northern Finland with these types of structures and they have been dated to a time period of 400 BC–600 AD. They resemble furnaces found from Russian Karelia indicating that the technological knowledge for making iron with these types of furnaces arrived via eastern river routes. The stone box furnaces were built underground out of slate slabs into a rectangular box with a lid and they often had a clay lining to protect the structures from extensive heat. The front side of the furnace had a gap for the slag to flow out into a slag pit, which had been dug in front of the structure. The thesis first outlines the study of the sites with stone box furnaces and their structural details, which were analyzed in order to form the basis for the experiments. The experiments concentrated on the placement of iron ore inside the furnace and how that affected the behavior of the furnace and the quality of iron. Three experiments were conducted in the Kierikki Stone Age Center in 2014 and have been reported in detail in the thesis. The results indicate that the ore placement affects not only the quality of iron but also the slag flow and formation as well as the duration of the smelt. Scattering the iron ore all around the furnace resulted in small individual iron blooms and placing it on the edge of the blast zone made the smelt slower and yielded a slaggy iron bloom. The best results were achieved when the ore was placed on top of the blast zone producing a good quality bloom and allowing the slag to flow out. Moreover, the decay of the experimental furnace was observed for two years and the observations are analyzed as well. The observations and results from the experiments were compared to the archaeological material and sites yielding interesting results. The comparison resulted in both similarities, like possible reasons for broken lid stones, as ...
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