Monday, April 19, 2021

Revisting the Smelting Area

Casting around for a direction to take in future experimental iron smelts...

Considerable work was undertaken over January through March, leading up to the EAC12 Conference. April 1 was the presentation date of 'Now with 70% less clay! Experiments with Viking Age Icelandic Turf walled Iron Smelting Furnaces' with co-authors Kevin P. Smith and Neil Peterson. (1) This included the writing of the full 73 page formal paper. 

Considering the body of work involved, a number of conclusions suggested there was still aspects of the turf stack system still to be investigated by future experiments. Primary was testing multiple firings of the full build structure. 

To that end, I will be undertaking a full construction of the 'turf cone in a frame' furnace for the 2021 smelting season. (2)

Tentative build plan (north would be to the left of lower image)

The first step is taking a look at the existing smelt working area. Typically the majority of our past smelts have taken place with at least the working crew under the cover of the pole framed metal roof. As this space itself is about 3 x 3 m, the Hals build is simply too large to fit. The previous experiments had the individual furnaces placed along one edge of the roughly 60 cm tall earth bank, with it's block retaining wall, that makes the west boundary of our normal working area. Right now the furnace base remains of our last series (Icelandic stone block) is still in place from the last smelt (November 2020). 

At this point I have already spend several sessions re-arranging and marking out areas for designated purposes : 

April 18, view towards roughly SW

The edge of the overhead is roughly at the extreme left edge of this image.

You can see the remains of the furnace base and lower stones from the last smelt, at the left front of the image. These have been photographed (scaled grid). And may be retained for recording erosion into at least the near future.

The area immediately behind this (so mid ground, left) is a disorganized pile of smaller flat stones and other rocks. My intent is to actually pull these up, sort those useful against future constructions, an collect small pieces for use as fill (south end of the pond).

To the left rear is the 8 x 8 foot deck plate. 

I have measured off the required 2 x 2 m area that will be covered with the Hals build. (also framed with red lines on this image). The pail seen marks roughly the centre, where the furnace shaft will be positioned. As it turned out, I had one piece of 'aged beyond construction use' timber that was just the exact size to help with laying out. I will be lifting all the grass sod in this area, and filling the gap created with clean sand. (The first part of this you can see in the far right corner.) This will both help gather the considerable amount of cut turf I need, and also create an obvious visual base against future examination of the working area.

The 'front' of the furnace, for possible placement of the bellow, and certainly for slag management or potential bottom extraction, will be the side closest to our view here (the north side)

Those familiar with the normal working process at Wareham will note that I have slightly re-positioned the concrete slabs (which had been underneath the sand box area created for the June 2020 'Bones' experiment. The existing slabs have been shifted slightly and re-leveled on a new sand base. There is now a north to south axis, 4 feet wide and extending six feet (use of existing 2 x 2 foot square slabs). You can see the spacing here is a bit tight, the slabs will be running right against one timber wall of the Hals build. Normally this is where the breaking frame for charcoal is positioned. On a typical weekend, usually there is a tarp on poles overhead put up to shield from sun or weather.

To the far right rear, you can see a rebuilt sand pad. This will be used to contain a new 'standard' clay cob build furnace. The intent here is to leave this furnace, within it's clear area, as a long term erosion effect experiment. The hope is for at least 10 years of annual observations.

You can also see the wooden stump that has been used for initial compaction of the hot blooms for the last several years. This stump is still in fairly good condition, and has enough clearance around it with the new stations to still allow for 3 or 4 workers.

There are a number of main purposes for undertaking this build here at Wareham :

a) By undertaking this build over some extended time, it will be possible to make detailed records (measurements, scaled drawings, photographs) of this entire process. 

b) The slower pace of work should allow for more careful control of the process. Additionally more time for contemplation, discussion and possible modifications as the build progresses.

c) Part of the experimental series being proposed includes not only multiple uses of the same furnace, but also some observation of the impact of weathering on the structure over time. Retaining the structure for at least an over winter is required.


Expect further discussion of the contributing elements towards this build and the iron smelt itself, over the next weeks...


1) The 15 minute narrated slide presentation version now available on YouTube:

2) COVID isolation requirements remain in full force in Ontario as I write, at this point there are basically NO private gatherings allowed, through to at least mid May, under the current Government guidelines. Although this certainly shifts the bulk of all the preparation work on to my (getting worn) shoulders, I will be endeavoring to have the furnace built for my originally proposed Saturday June 20 date.

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

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