Monday, December 07, 2009

Vinland Smelt - Matching the Evidence.

How close are our experimental attempts to the actual recovered Archaeology?

The purpose of our most recent series of experimental iron smelts is to attempt to match, as best we can, the single firing that occurred at 'Leif's Houses' some time about 1000 AD.

Leaving aside all the problems and issues related to the difficulty of ever being able to reproduce a historical event, especially one so poorly understood as what may have actually happened at Vinland, what does the archaeological evidence indicate. Do our attempts leave similar traces on the ground?

For the LAM 3 smelt (November 7, 2009), the primary equipments were all Viking Age types. Most importantly, this included the use of human powered air via a double chamber bellows. One of the possible interpretations of the large pit in the front left of the LAM site is that it marks the location of a slack tub*. (For a full discussion on how the current experiment series was designed, see the earlier postings : 'A Furnace for Vinland', 'Construction Possibilities', 'LAM Smelt Working Area' )

Diagram of Furnace Hut.
LAM 3 Rough Equipment placement.
Overview after LAM 3 smelt.

Of course, the archaeology records only the remains of the complex series of steps that combine for a successful iron smelt, and its secondary processes in compacting the bloom and converting the mass to a working bar. First, the archaeologists will remove materials down to the original ground surface, removing (and hopefully carefully recording) materials above this. Second, it will only be the last of the working stages in the overall process that are likely to remain as evidence. The images of our 'excavations' have been altered to roughly match the scale, orientation and size of the original LAM excavation photograph.

Furnace Hut, Remains of Hearth (to ground surface)
Remains of LAM 2 (to ground surface)
LAM 3 Remains after extraction

The large stone found to the left of the hearth in the Furnace Hut at LAM is interpreted as being used for some form of blacksmithing work (compacting bloom to bar?). It is my opinion that it was placed after the primary smelt sequence.
The central photograph was taken after the LAM 2 smelt on October 11, 2009. The next day the smelting area was 'excavated' by Anitoly Vencovcey. The image shows the remains cleared away to the original ground level, 'surface polished' as in the LAM excavation photo to the left. The primary difference is that the cleared surface is flat, while that at LAM shows a shallow bowl shape.
The third image is of the LAM 3 experiment, the remains of the smelter base just after extraction. In this case the extraction process was undertaken a bit too slowly, so dropping temperatures inside the furnace caused the slag mass to congeal around the bloom. The effort of pulling the mass free resulted in the top 2/3 of the furnace being pulled away.
Now, if work had continued past the initial extraction and primary consolidation step, the furnace base as it remains would have been retained and used as an oversized forge hearth. The fire required for consolidation of a multiple kilogram bloom needs to be significantly larger than that needed for general blacksmithing work*.

* A separate discussion of these topics and interpretations will be made later.

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

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