My work with iron smelting began after William Short of Hustwic was visiting a farm in Iceland. There was a large hill on this farm that turned out to be made of slag, a byproduct of smelting iron. The accepted knowledge was that Iceland did not have the materials needed for smelting and that it had never been an Iron producing country, but this giant slag heap stood in contradiction to that fact. William came back to Hurswic with this puzzling piece of data and we began work to crack the secret of smelting Iron in viking age Iceland.
A small group of Hurstwic folks took a trip up to Canada to learn viking age smelting techniques at Wareham Forge with Darrell Markewitz. We took this knowledge back to Massachusetts and started running our own smelts. Traditional smelting furnaces were made with clay, sand, and horse manure but Iceland doesn't have the right kind of clay to build furnaces with. Icelandic clay melts at a lower temperature than is needed to smelt. We started doing chemical analysis of various materials that could be added to the clay to increase its temperature resistance and would have been readily available in viking age Iceland. We found that burned horse manure contained a chemical that might do the trick. There was also archaeological evidence that turf was a furnace material and a few stones were found in the smelting sites. We found that the outer walls of the furnace could be constructed with turf, the stones formed an archway where the bloom could be extracted and clay could be used to just line the inside of the turf greatly reducing the amount of clay needed.
We took all that we had learned and went to Iceland in the late summer of 2019. We held a three day long iron making festival at Erikstadir, the site where Eric the Red had his homestead, and successfully smelted the first Iron in about 900 years made entirely from Icelandic materials. The National Museum of Iceland is currently putting together an exhibition about viking age smelting and the work we did at the festival in 2019