Friday, May 25, 2012

Hals / Icelandic Five - Furnace Construction

As I had detailed in Wednesday's post 'Return to Iceland', Saturday May 26 will mark our return to the Hals / Icelandic series, based on excavations and insights from Kevin Smith.
Our smelts # 38 , # 39 in Fall of 2008 had tested the general work dynamic around the Hals style construction, plus use of a bellows plate and blow hole system. (This method does not use a tuyere, and has been researched and tested by Michael Nissen of Denmark.)

Field drawings of Icelandic Three & Four
 Because of too much going on and too little time (brain power!) this will be a fast overview - primarily in images.

Icelandic Five will serve two purposes:
1) To re-acquaint the team to the Icelandic system
2) Reduce the furnace wall thickness to 3 cm.

I cleared out the remnants of the 2008 furnace and built a new furnace yesterday (Thursday).
At the end of the last smelt, a plastic pail had been placed down the interior of the furnace. A metal cover was placed over the top. Normally liquid water seeps through the earth bank every spring. 

Remains of the 2008 furnace. The upper portions consisted of smaller pieces of sintered clay held in place by soft raw clay (on the earth side). The lower portions had little heat effects visible, and were still soft clay.
Portions of the lower part of the original solid clay walls. Roots have grown into the clay over the last three summers, actually helping to re-enforce the portions of the walls that remained.
The hole remaining in the earth bank after all the previous wall material had been removed
The first layer of the furnace wall. The metal rule is 3 cm wide, and was used as a gauge to set the rough thickness of the walls. Note how the shape is determined by the hole in the earth bank.
Finished construction, with old sand/ash packing fill. This will both help dry and stabilize the soft clay. The two boards placed against the front surface hold the exposed wall in place

Today (Friday) later in the day, I will remove the packing material. Then a small tap arch will be cut in the front. For this smelt the standard ceramic clay tuyere will be used, mounted above the taping arch. Extraction will be from the top.

Finally, a small wood splint drying fire will be started. The ideal would have been to have constructed the furnace much earlier, and allowed it to air dry for several days.

For smelt day tomorrow, roughly 20 kg of DD1 (red oxide bog ore analog) is already on hand. A small amount of previously prepared (crushed and sized) charcoal is on hand. The remainder required will have to be worked up while the furnace is pre-heating.

Stay tuned!

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

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