The chaîne opératoire of ironworking

Alchemists of their own accord

The production of steel, and the working of iron in its own right, requires multiple factors. First, both Prof. Austin Mason and our guest, Martin Pansch, described different factors surrounding the historical scarcity of the materials needed for blacksmithing. First, intensive mining for the purpose of extracting iron and coal was not a coordinated, widespread, or systematic pursuit, at least in Anglo-Saxon England. Not only could both be found in places near to the surface, but the location where they could be found together — bogs — are simultaneously one of our best sources for well-preserved archaeological specimens that help us build the material world of the people we study. Bogs also provide peat, which, to even today, has been used as a cheaper, more accessible source of carbon-based fuel.

Additionally, Martin mentioned that a very large majority of the iron used in the medieval period was recycled — melted down from other purposes and past forms. The question of what to melt down would be informed not only by circumstance but by culture, as iron not only is a material of function, but decoration.

Carbon would then be introduced to iron by combining charcoal with iron in a type of crude smelter called a bloomery — sometimes dug into the ground or standing, constructed of stone brick. Air would be introduced to raise the temperature as high as possible, often using double bellows — one for each hand –. to maximize oxygenation. The resulting alloy is steel, which can be refined further, and eventually rendered into whatever form necessary for working. It is important to note, however, that the high melting point of iron made liquid melting and casting a difficult to achieve, and thus very rare occurrence. This was however done with bronze, which has a lower melting point.

Steel; why and how?

As described prior to the lab itself, ironworking required certain prerequisite technologies and anthropological circumstances to facilitate a break and standardization out of the metalworking approaches that dominated human metallurgical arts prior thereto. Prior to the cementing of iron as the metal of desire, the Bronze Age (approximately from 3300 to 1200 BCE) saw…interestingly…bronze as its primary material of choice. This alloy of copper and tin has a comparatively much lower melting, and thus softening point than many others, and its comparative plenty, adjusted to this workability, made it the human smithing metal of choice for that very long period of time. Tin in particular allows the metals it alloys with to maintain a hardness that either metal alone cannot maintain. This is its role when interacting with copper for bronze, and lead (now aluminum) for pewter. Alloying metals in general also can help stabilize the respective components’ ions that would otherwise be much more prone to oxidation (rusting). We would see this in the steel we were presented’s absence of rust compared to the wrought iron’s plentiful rust.

Rust: sorrow of the smith?

Preventing rust was a major reason for synthesizing alloys throughout history, implanting weak, brittle spots in the metal, expanding in veins underneath the surface, and corroding holes. This is the reduction–oxidation (redox) process. With Iron (Fe) and Oxygen (O), we see this as:

4 Fe + 3 O₂ → 2 Fe₂O₃

Here, positively-charged iron ions receive an electron from the negatively-charged oxygen ions, making a stable, and (for the metalsmith) unfortunately resilient bond.

As undesirable as rust, Iron(III) oxide, was for early applied metallurgy, the substance itself, especially as the most common form in which the comparatively common iron ore is extracted, became an asset of human cultures worldwide.

As described by a previous guest lecturer for a preceding lab on wool and dyeing: Alejandra Sanchez, Iron(III) oxide, also called red ochre, was used as a principle red, orange, or yellow, dye — naturally appearing in different shades depending on state of extraction. It has been, and continues to be used by different cultures as a pigment for paintings on canvas, caves, the body and one’s hair, among other plentiful and even contemporarily expanding uses. With that ubiquity, it has intangible qualities and interpretations in numerous cultures.

Steel as the star child of the steam era

During the industrial period, as more efficient ways of smelting, casting, and all metallurgical arts and processes became more available, newer alloys that maximize this goal of rust resistance were created, such as the now ubiquitous stainless steel. Martin’s reference of the quickly-made-obsolete Bessemer process — the first large scale process for the industrial production of steel — made producing steel and wrought iron cost-effective for the first time, but also helped carry forth a firm shift from the popularity civil applications of iron versus steel.

Metal magic?

Similar to the metaphysicality or cultural intangibility that can inserted into creations such as pottery and the associated funerary traditions that may utilize pottery as a part of ceremony, metalworking has a similar anthropological manifest. Many cultures, historically and presently, have or continue to have particular associations with metalsmithing as a profession. Certain spiritual, cultural, or other qualities can be put upon the craft or the crafter, resulting from the process itself. Material from the earth (ore) is combined with charcoal — itself a transformed material, to make a metal that is further heated to red-hot, and beat into however one wills it — sometimes hot enough, or hit hard enough, to see sparks or glitter fly.

The associating observations could lead to associations of blacksmithing as a manifest of magic as much as an art, or often witchcraft, as seen in Horn African folklore. Myth can of course embellish these qualities too, such as the story and associated patronage of the Greek god Hephaestus. These myths can develop as complimentary elements of otherwise “substantive” observations of blacksmiths: expectations of having “one arm stronger than another”, for instance. Or even stereotypes of “brutishness”.

Lab Setup

As each of the labs that involved fire — cheesemaking, pottery, dying, and, of course, cremation — this lab was conducted on Carleton College’s Mai-Fête Island amidst the goose-abundant Lyman Lakes. We were provided five wood/coal-fired forges by Martin. Some of these were square, and some of these were round. Each of them had turbine bellows that used a series of gears to produce a strong, fast rotating fan out of a strong, torqued turn of the crank. The older forges had their bellows directly attached to the forge “body”, while some of the newer ones had a separate standing forge with a duct that could be freely attached and removed from its port into the forge.

Our goal with the lab was simple:
We were to each produce a nail and a rove from a piece of carbon steel.
This, naturally, turned out to be more difficult than expected.

The nails we made sought to emulate those that would be made by viking shipbuilders for their seafaring clinker-built vessels. While their heads could be a variety of purposeful shapes — generally a square or a circle, dependent on the shape of metal being forged — we were not asked to modify the nailhead shape (likely for time). A square bar would have form a square head, for instance.

The nails’ associated roves are a type of early washer, inserted behind the nail’s insertion site, fastening the wood in between the nailhead and the rove.

Black(smith’s) Gold:
Experimental variables between metallurgical coal and charcoal

The weather during the lab was temperate and cloud-free, baring those that we would make through one of our two fuel sources: bituminous coal. Out of what was five forges, three of them two closer to the east end of the island, spent more time burning charcoal, and another two, closer to the west end of the island, burned only coal.

Observations, variables, and data

Nailed it….

This lab was the first that we’ve had so far that utilized over the full length of time allocated for it (and I for one wish it went a bit longer). Of each student’s attempt, a great majority of the nails made were quite relatively consistent in length, straigntness, and bearing a prominent head. I also do not believe that there was any noticable difference between the speed at which nails could be made dependent on the fuel a forge used.

Rove, rove, rove (for) your boat…

As roves started to be made made only nearing the end of the lab, only a portion came out satisfactorily, despite the quicker and simpler process behind their production. It should be noted that, identically to the making of the nails, the quality of each rove progressively increased as each new rove was made. The comparatively higher amount of nails made in comparison to the amount of roves is simply due to how close to the end of the alloted lab-time roves began to be made. Therefore, it is likely that roves would soon meet the quality of the nails made just before, if there were more time, and likely comparatively faster, given how drastically lower the amount of work and time is needed to make a rove compared to a nail.

There was one rove made of wrought iron, as we were only offered to attempt using it to make something after we were taught how to make a rove. There were, to my knowledge, no nails were made of the wrought iron. The wrought iron, according to Martin, was much less forgiving and difficult to work, and conducted heat differently compared to the now-familiarized steel.

Post-lab: X-ray-armed archeology?

After the lab, we invited Sarah Kennedy, Carleton College Assistant Professor of Archaeology & Latin American Studies, who introduced us to pXRF: Portable X-Ray Flourescence. This technology manifested as a field-portable (naturally) pistol-grip device that functioned by emitting x-rays upon an given object, ionizing the atoms in the material, causing the release of electons, whose expulsion from a respective atom’s electron cloud results in a flash of energy in the form of light. That light — photons — are then detected by the device, quantified, and analyzed in a similar principle to the method done in spectrometry. The result is the ability to quantify the amount of atoms of a particular element within the scanned object. This allows a very gross understanding of the metarial composition of a given substance.

Below is the flourescence spectrometry of a piece of bloom and wrought iron, top-bottom respectively. Bloom is the raw product of the making of steel in an aformentioned bloomery. Wrought iron is a refined, slightly reinforced form of iron, popular in the 19th century.

There are many variables in utilizing this technology, however. While there exist different detection models that are able to account for some compounds such as Oxides, it purely provides information concerning the presence- and percentage of a particular element within a substance. This means that it cannot provide any accurate information on how certain compounds may manifest in a given substance on the molecular level. Iron could combine with oxygen and other elements in a number of ways. Regardless, it provided an interesting idea of what we were working with on the level of alloy analysis. Another variable that is less significant for our lab, is the inability to account for the depth of evaluation — this being that the penetrative depth of the x-rays, and the obscuring of photons due to variables suh as reference material density, affect the accuracy of the data recieved.

We had tested a couple of materials from the lab using pXRF to better understand what we were actually working with on a chemical level. We also tested from jewelry from various different students, and Prof. Mason’s wedding ring, the latter of which we confirmed the authenticity of, after a few humorous hiccups caused by a miscalibration. Ultimately, pXRF introduced a new quantitatively empirical lens to our archaeological methodology that only helped to illustrate the interdisciplinary nature of the study.

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