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An experimental archaeology project considering the stone slab box furnaces used for iron smelting

Date: 
Friday, 13 June, 2014 to Friday, 27 June, 2014
Responsible: 
BA Joni Karjalainen and archaeology student Juuso Vattulainen
Number of Participants / Visitors / Audience: 
2/50/300

Kierikki Stone Age Center organised an experimental archaeology project considering the stone slab box furnaces used for iron smelting. The furnace is dated to the Early Iron Age (500 BC – 400 AD) and they have been found around Finland, northern Sweden and western Russia, close the border of Finland. The furnace type has not been thoroughly tested before, thus we decided to experiment the construction in action.
The furnace has a rectangular shape and possibly half of it was dug underground for constructional durability and to maintain heat. The core structure was made from stone slabs, mostly flat slate. The furnace was then lined with clay to insulate the stones from the intense heat inside the furnace. The furnace was closed with a stone lid to keep the heat inside.
Materials used for the furnace, fuel and ore were acquired from the local area. Everything considering the using of the furnace was done with tools and materials found in the Early Iron Age.
We ran 3 experimental smelts with different kind of variables considering ore amount, ore positioning in the furnace, tuyere and lid stone configurations, which were all documented on close detail as BA Joni Karjalainen is writing his Master’s Thesis on the subject.
The pre-experiment was done during the OpenArch’s Dialogue with Science conference held at Kierikki Stone Age Center and participants were able to see the furnace in action. We managed to make iron in the smelt, although the bloom was relatively fragmentary. The two other follow-up smelts were done during the open hours of Kierikki Stone Age Center and each of them was more successful as we learned more about the structure.
For us many questions were answered in the three smelts and more new questions rose as the smelts we did weren't fully successful. We're hoping we can answer those questions in the coming years.

Images

Photo Jackie Wahrgren, presentation during...
Photo Jackie Wahrgren, presentation during...
Photo Jackie Wahrgren, presentation during...
Photo Jackie Wahrgren, presentation during...