Wednesday, April 15, 2015

Icelandic Grass Sod Furnace - April 25

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.
The full discussion of the Hals evidence and how it is being interpreted can be found on the main Wareham Forge web site : 'Working towards an Icelandic Viking Age Smelt'
The descriptions of the previous five experiments in this series can be found on the main Wareham Forge Iron Smelting documentation

The original plan for 2014 was to return to the Hals / Icelandic project.
The furnace construction was started, but with one thing following another (for me personally), the build was never completed, and no actual iron smelts were undertaken.

For a discussion of the current build see : Return to Hals / Oct 10, 2014
This year, I fully intend to return to the Hals / Icelandic experimental series. The cancellation of Early Iron 4, originally scheduled for the weekend of April 25, puts an available hole in my schedule. Now that the snow has (finally) cleared off the smelting area at Wareham, I have been able to assess the condition of the work from last fall.

Build in October 2014
With the help of Neil Peterson, last fall the construction was started on a full sized build of the Icelandic pattern furnace.
- To conserve materials, the area where the previous smelts in this series had been built was fully cleared out. This gives a hole into a roughly two foot high earth bank, reducing the amount of timber framing required for the full above ground construction.
- By a nice coincidence, clearing ground for a planned garden means pulling off more than enough grass sod to allow a full 60 - 70 cm height.
- The central shaft is being created by using a metal form - in this case a roughly 35 cm diameter section of metal air ducting pipe.
- At the front is a stone (and brick) support to allow for a taping arch. The interior gap will be filled with more grass sods. The flat stone seen should support sods making the front upper wall, if the lower taping arch needs to be opened.
- The general plan is to set a ceramic tuyere near the top of the stone work - but inside the interior space. Some refining of the size of this stonework still needs to be made to ensure the normal 23 degrees down angle can be used.
- This is intended to be a top extraction, with the space between the conical sod walls and the space at ground level filled with earth removed when clearing the needed space into the bank.
- The ore for this smelt is likely to be the bog iron ore analog (from iron oxide powder).

Note to Readers:
The smelt itself is set for SATURDAY APRIL 25.
This will be the usual 'semi-open' event here at Wareham.
Individuals interested in attending are welcome - but should contact me via e-mail to let me know how many people to expect.  Like usual, there are plenty of 'dirty jobs' to be undertaken.
Pre-heat starts for about 9 - 9:30 AM
Main sequence start for about 11 AM
Extraction expected about 4 - 5 PM

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

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