Friday, October 10, 2014

Return to Hals / Icelandic Furnace

From Fall 2007 through Fall 2008, plus one in Spring 2012, DARC mounted a series of five iron smelts specifically aimed at re-creating Viking Age furnaces from Iceland. The archaeology was based on excavations by long time friend (and unofficial adviser) Kevin Smith at the Hals site. This was a long term, 'industrial' scale iron production operation, with the remains of a number of bloomery iron furnaces uncovered.

As a refresher, the Icelandic system is basically a cone made of piled up grass sod, with a cylindrical hole in the centre (the furnace). At Hals, these were constructed entirely above ground level. The cone was then boxed with timbers. The space between the timber and cone was then filled with earth to create a working surface at the top level of the cone / furnace mouth.
Possible Furnace Construction - based on Hals
More details on the site, and the logic behind our reconstructions, can be found in the semi formal description 'Towards an Icelandic Smelt'

An important difference from other furnace builds we have undertaken is that there is no true clay found on Iceland (our normal construction material!) My suspicion is that at Hals, the sod itself forms enough barrier to contain working gasses and heat of the furnace. The timber and earth fill is merely to create the elevated working area for charcoal and ore workers.
I have yet to calculate the required timber or earth needed for the full above ground build. Obviously there would be a considerable volume of both grass sod and earth required. The timber would have to be purchased, most likely in the form of wooden fence posts.

Remains of the Fall 2008 Furnace
Over the earlier series, the working furnace was set back into the low earth bank on one side of the smelting area here at Wareham. (This done to conserve on the materials required for a full build, especially as individual 'problems' were investigated.)

Intended construction - Icelandic Furnace
What I am considering is to simply use the existing earthen bank to contain the lower part (roughly half the needed height) of this construction. This will limit the amount of dirt needed to be dug and shifted. Also greatly reduce the amount of timber required for the upper box construction.
The lower part of the furnace face will be constructed of stone - in effect creating a 'slag room' style, similar in this aspect to what was used for the Turf to Tools project.

The result here is that Sunday October 12 will be a * working * day at Wareham. Sod will be cut and stacked (from a piece of yard that is intended for a garden). The old furnace will be cleared and some earth dug away. Ideally at least the base structure will be laid for the new furnace.
Other hands extremely welcome!

The full build will all be (hopefully) completed in time for a full run of the Hals system (smelt) on Saturday November 1.

No comments:


February 15 - May 15, 2012 : Supported by a Crafts Projects - Creation and Development Grant

COPYRIGHT NOTICE - All posted text and images @ Darrell Markewitz.
No duplication, in whole or in part, is permitted without the author's expressed written permission.
For a detailed copyright statement : go HERE