Sunday, January 24, 2021

Paper / Presentation for EXARC 12 in March/April

 2021 March: 

12th Experimental Archaeology Conference EAC12, World Tour 


I will be one of the presenters at this event : 

'Now with 70% less clay!' Experiments with Viking Age Icelandic turf walled iron smelting furnaces. 

co authored with Kevin Smith and Neil Peterson

Our segment will be included in the segment being hosted by the Dark Ages Re-Creation Company, later in the afternoon of April 1. 

The abstracts for all the presentations can be found at : 


Register for the conference :

This is free of charge but enables EXARC to reach those who are interested with up to date information.


Abstract :

Iceland's Viking Age settlers came from regions with long
traditions of bloomery iron smelting. They faced a significant
problem, however, as the clay typically used in Iron Age furnace
construction was either unsuitable, or extremely limited, in
Iceland. Excavation of a major 9th-10th century iron production site
at Háls by Kevin Smith illustrated an alternative – walls made of
conical stacked grass turf, with or without a thin clay lining.

From 2007 to 2016, a group of independent researchers in
Ontario, Canada, executed a series of eight experimental bloomery
iron smelts to investigate possible furnace designs and working
methods based on this archaeological evidence. This series related
to a second concurrent project investigating iron smelting at
Vínland (L’Anse aux Meadows NHSC), and more recent furnace builds
suggested by excavations at Skógar, Iceland.

This paper will describe how the archaeology at Háls was
interpreted into a possible working system, provide an overview of
how individual elements were tested and combined for successful iron
production, and suggest directions for future investigations.
Further, this report helps to illustrate how valuable insights can
be provided through direct experience, even with limited resources
for experimentation.



Monday, January 11, 2021

Truth in Reporting - Sample Iron content


(Lies, Damn Lies - and Statistics)

(originally posted 1/11/21, with corrections 1/19/2021)

Be careful about what some people are stating, when it comes to promoting, rather than reporting, their work with experimental iron smelting.

‘Data’ posted to ‘Iron Smelters of the World’ Facebook Group

This sample of iron ore was reported as containing 89% iron!

Do you see the impossibility here?
(Do you remember your high school chemistry?)
Naturally occurring bog iron ores (what I call ‘primary bog iron’) are mainly composed of FeO(OH).
The atomic weight of iron is 56, of oxygen 8, hydrogen 1.  So FeO(OH), combined, has a total weight of 89. Of which only 56 is the iron. The maximum amount of iron possible in pure Fe0(OH) is 63%. (1)

Many of the iron ores used by current experimenters contain the other forms of iron oxide, being Fe2O3 (red) or Fe3O4 (black). Here the maximum possible contribution of the iron by weight is slightly higher, at 70 (2) or 72 % (3)

Obviously, any naturally occurring bog iron ore is going to have other components. One of the major ones is typically silica - SiO2. Again, atomic weight for silicon is 28, so here the silicon makes up 47% of that component. (4)  A typical primary bog ore may vary considerably in silca content (usually the other major component), in the range of anything from 5 - 25 % of the total weight.

The amount of silica available is also extremely important in a functioning bloomery furnace. Silica is the major component of the slag, which combined with some of the iron, creates the slag bowl, which both contains and protects the developing metallic bloom. Another major source of this needed silica is from melted furnace walls, so the composition of the furnace plays a role (type of clay, use of brick or stone). Most naturally occurring ores are more likely to contain too much silica (so also less iron). Although some industrially prepared ores (especially hematite blasting grit) may require addition of some silica by way of sand, there is usually no reason to add any kind of 'fluxing' agent into a bloomery furnace. (5)

A last important consideration with a natural ore will be the organic and water content. Both of these do burn off (the Loss On Ignition measurement). This will not show up on many lab analysis methods. It becomes important when actually calculating raw ore to final bloom yields however. Pre-roasting ore now becomes a factor.

My team here, which suffer from not having any naturally occurring ore in our region, has worked with more different types (and iron concentrations) of ore than most other groups. In my own experience (which is considerable), you need at least 45 - 50% iron content in the ore to expect any successful production from a bloomery furnace. Even a ‘good’ natural ore is typically in the range of 65 - 70 % Fe2O3 - which places it in that same 45 - 50 % iron content range.

If the sample reported above was 89% iron oxide FeO(OH)- it most certainly would represent a reasonable quality ore. This would be 56% iron content however.  For comparison, the samples analyzed from the 2001 excavations by Dr. Birgitta Wallace at L’Anse aux Meadows (the Norse site in Vinland) showed iron in the 58 - 68% range . (6)

I’d be curious to see some actual reporting of the iron bloom yield figures from any smelt attempt using this (clearly) mis-represented ore, as illustrated above. Waxing poetic about ‘produced excellent iron’ is meaningless. Ore to bloom yield, density, potential carbon content - those are what current serious researchers and experimenters offer up as description of their results. 

I'd certainly suggest anyone distorting basic science should not be trusted about any other claims made...





5) This piece was sparked by a recent 'first time' question on that same 'Iron Smelters of the World' discussion group. Bloomery furnaces almost never require addition of additional materials as 'flux'. In the production of liquid cast iron, the mechanism within the furnace is quite different. Here it is quite important to ensure the already high carbon iron (which has a lower 'burning' point that solid bloom iron) is protected from the air blast inside the furnace. Historically, powdered limestone was added for just this purpose.


Saturday, January 09, 2021

Elora Sculpture Project - 2021

(from my submission for 2021)

‘An Undiscovered Plant - with a cure for cancer’

‘My. how peculiar! Just what is this? It’s not like any plant I’ve seen before. It’s so BIG. - and so strange looking…’
This sculpture is in the form of a huge jungle (?) plant. A cluster of arching stems each hold individual frosted glass ‘flowers’. Towering above these are a group of huge and complex ’seed pods’. Bundled at the base are long blade shaped leaves.
For the Elora Sculpture Project 2021, I wanted to to return to something more illustrating hand forging methods, and more subtle in theme. Those familiar with my past work have seen my use of re-shaped structural steel, the closest parallel would be the 2014 contribution ‘Spears of Summer.
In truth it is the title that conveys the meaning to the piece, beyond creation of the fantastic. I also wanted to be less obvious that last year’s ‘Last to Sea’, and ‘Legacy’ in 2018. The starting point here was suggested by the 1992 film ‘Medicine Man’, about an isolated scientist in the Amazon, pursuing a plant based cure for cancer, and battling the destruction of the same rain forest where the rare plant can be found.

This will be a physically large piece, the three ‘seed pods’ standing about 6 feet tall (about 1.75 m) and extending to roughly 3 feet total diameter (about 1 m). The ‘flower’ elements will be at roughly five feet (1.5 m). The ‘leaves’ will extend up about 1 1/2 - 2 feet (about 50 - 60 cm) from the base.

The inspiration for the seed pod elements came directly from 'Art Forms in the Plant World' by Karl Blossfeldt, an amazing collection of highly detailed black and white photographs from the early 1900’s. This specific form is based on the image 'Common Chili-nettle. Seminal capsules' - which in real life are only about 5 cm long. In preparation for this submission, I undertook a prototyping session, with the final forged element here about 12 - 14 inches long and about 3 inches wide (30 - 35 x 8 cm). The outer covers are spiral wraps of flattened  3/4 inch angle, so the width each of the three pieces used is roughly 4 cm. In the image of the prototype, the core is formed of a bundle of twisted angle. I was not entirely happy with the result (and it proved technically difficult to control). So in the final sculpture I will be using a bundle of twisted round rods as the cores.  

Image Inspiration

Initial Prototype

The the interior core will be highlighted by use of bright orange - red paint, the exterior coloured a dark green to match the other surfaces.

Each of the ‘flowers’ is formed by a matching frosted dark blue glass ‘bell jar’. These are each 15 cm long, and 12 cm in diameter on the open rim. Each is held in place via a tendril ‘basket’ forged from six pieces of 1/ 4 inch diameter round rod.

All the ‘stems’ will be forged from structural channel, collapsed into a distorted tube like profile. The base leaves will be forged from flattened wide angle. All the individual elements will be welded together at the base. The main stems will be attached first, with some smaller pieces added to ensure significant strength. These pieces will be hidden by the spray of leaves around the base that are welded in place after. As mentioned, the whole piece will be painted with a dark green industrial enamel.
The exact shape at the base may need to be a bit wider in proportion than indicated in the drawing - to accommodate the usual bolt pattern. ( I may chose to mount the sculpture to an irregular stone slab - and idea still under consideration).

I think the final sculpture will be striking and have significant presence. For that reason the committee may chose to place it at one of the peripherial locations. It remains my hope that the title alone will prove though provoking enough to the viewer.

Bio :
Darrell Markewitz has been working as an Artisan Blacksmith since a student at Ontario College of Art in the late 1970’s. He established the Wareham Forge in 1992, creating forged metal objects in his distinctive ‘Rivendale’ style. He is known for his work researching and replicating objects and techniques from the Viking Age. He has contributed work for the ESP every year since 2013.

Monday, January 04, 2021

Iron, the Blacksmith, Horseshoes (and the Devil)

(a trip down rabbit-holes…)

This article originally written for Ontario Artisan Blacksmiths Association quarterly newsletter, the Iron Trillium (published Summer 2020)

GOLD is for the mistress - silver for the maid" -
Copper for the craftsman cunning at his trade! "
" Good! " said the Baron, sitting in his hall,
But Iron - Cold Iron - is master of them all."

Rudyard Kipling : 1909

With my long interest in particularly early European history, the connection of iron to the ‘magical’ has long puzzled me. Explore any folklore, and this connection is certain to be found. The belief that iron is toxic to the ‘other worldly’, to the Fairy Folk and Demons. Just where does this core belief come from?
Iron is unique to other human worked metals (in ancient times at least) in that it was the only material that does not exist in it’s metallic form naturally on the earth’s surface - outside of one unique and rare situation. This is as pieces of nickel iron meteorites. Metalworkers in copper and later bronze would have been the ones to first attempt to form this very uncommon material. Ancient references (primarily Egyptian) link this first iron to the gods (1) The myths and legends around human creation of iron most often detail how the making of iron was a secret ’stolen from the gods’.
Producing iron metal from rust like ore is a counter intuitive and very complex undertaking. So much so that archaeologists are uncertain just how anyone ever figured out the process (most likely developed over hundreds of years of trial and error). (2) Modern bloomery iron makers often joke about ‘making metal from dirt’, and to an ancient mind, the method must have seen almost mystical. And of course those early iron masters most certainly would not be talking, content to maintain their ‘mystery’.
Physically, iron was the only material known to the ancient world that could survive the elemental force of fire (iron could resist temperatures that would melt all other known metals). In fact it needed fire for its shaping. The blacksmith alone worked directly with the four primary elements in the process of creation : iron as Earth, forge as Fire, bellows as Air, and quenching as Water. This last added further ‘magic’, the way an individual piece of metal (specially selected as ‘steel’) was cooled could render that same bar soft enough to bend, or brittle as a piece of glass. (3)
Taken together, this places the blacksmith as an almost mystical figure, both the basic material, and working methods at the boundary between the known and the unknown.

In the original, Nordic, mythology, the Elves and other fey creatures can not bear the touch of iron, which burns them. (This much changed in the world of Tolken’s Middle Earth.)
In European mythologies, the Dwarves are masterful workers with all metals, including iron. They toll unseen in hidden hollows or within the mountains, creating weapons of legendary quality for gods and heroes alike.

I had been told that an old (ancient Celtic?) Irish / Scottish practice was to place a hand forged iron nail under the bedding of a newborn infant, especially before it had been baptized . The iron would scare away the Elves, who otherwise would attempt to steal away the human child and replace it with a ‘changling’. (Yes, over the years I have been asked several times to create an object for the expressed purpose.)

Just in passing - another linkage in European culture to iron as proof against the supernatural is suggested as the traditional use of of iron fencing around grave yards. The iron is though to become a barrier to contain the spirits of the dead. (4)

This all leads us (eventually!) to the best known association of the iron, the blacksmith and the Devil - the ‘lucky horseshoe’.

The connection between the blacksmith and horse shoes is something almost all of us reading have come to grumble about. ‘Are you making a horse shoe?’ is likely the second most common question heard when demonstrating (following closely on ‘Are you making a sword?’). Popular culture here in North America has firmly linked the work of the blacksmith to that single object.

History however, proves quite different.
Human made iron objects date back to about 1500 - 1200 BC.
Horse shoes date back potentially to about 400 BC, but are only known as a single artifact find of four bronze shoes. Protection for a horse’s foot is found during the Roman era, but as a kind of  leather boot called a hipposandal, not a nailed crescent. ( 5 )

Hipposandal On display at Vidy Roman Museum
Photograph by Rama, Wikimedia Commons

Near as can be determined by archaeology, the iron horseshoe appears to be a post Roman era innovation. The earliest artifact sample is dated to 481 AD (tomb of  Frankish King Childeric I in Belgium). The first clear reference to an ‘iron shoe with nails) is dated to 910 AD.

" Around 1000 AD, cast bronze horseshoes with nail holes became common in Europe. …The 13th and 14th centuries brought the widespread manufacturing of iron horseshoes.[13] By the time of the Crusades (1096–1270), horseshoes were widespread and frequently mentioned in various written sources.[7] …
By the 13th century, shoes were forged in large quantities and could be bought ready-made.[4] Hot shoeing, the process of shaping a heated horseshoe immediately before placing it on the horse, became common in the 16th century.[13] From the need for horseshoes, the craft of blacksmithing became "one of the great staple crafts of medieval and modern times and contributed to the development of metallurgy."[11]

(link to Wikipedia entry)(  6 )

So even as a single object, the iron horse shoe only has a clear 1500 year history (at best), against the total history of our craft running for some 3500 years.
An extremely important factor here is a consideration of the limited role of the horseshoe itself against the larger body of work undertaken by the ancient, historic, even traditional, blacksmith. ( 7 )

Horses themselves obviously do not require protective shoes in their natural state. For the first roughly 10,000 years of the (more or less) modern horse, they did just fine, environment, behaviour, and their constantly growing hoof balancing wear and damage just fine. Humans domesticated horses about 4000 BC, but it was the development of much later technologies that would result in the requirement for protection for their feet.
Domestication itself removed animals from the dry grasslands they evolved for and placed them in most often soggy fenced enclosures, softening the hoof.
Roads of stone and gravel, largely a Roman innovation, put them on to hard surfaces. (The development of the hipposandal)
Horses remain of limited use as a beast of burden through ancient times, so limiting the amount of stress placed on their feet. There are two main reasons for this, which are ‘solved’ by two Post Roman innovations.
The first of these is the stirrup, which allowed for truly effective combat from horse back. Without some way to anchor the rider, staying attached to the horse required one hand on the mane plus the relatively week grip via clenched knees. ‘You miss, you hit anything = you fall off’. Although certainly a major component in warfare, the horse represented a fast transport system, with the mass of the horse itself as the major combat effect. Introduced by the Mongols from it’s earlier development in Asia into Europe from the 600’s onward, the result was heavier and heavier armour loads placed on the horse - with more potential damage to those feet if not re-enforced.
The second was the horse collar. Before this innovation, horses were harnessed to a vehicle or farming tool by a strap that basically ran against their throat. The harder the load, the more they choked themselves. Fine for a pair of horses pulling a light framed chariot. Not effective for a plow, the reason oxen were the main beast of burden during ancient times. The long development of a solid ring, distributing the load over the horse’s shoulders and chest, is traced in China from about 400 BC through to about 400 AD :

The horse collar eventually spread to Europe c. 920 AD, and became universal by the 12th century.[21] The Scandinavians were among the first to utilize a horse collar that did not constrain the breathing passages of the horses.[22] …
When the horse was harnessed with a horse collar, the horse could apply 50% more power to a task than an ox due to its greater speed.[1][2] Horses generally also have greater endurance and can work more hours in a day.
(link to Wikipedia entry)

You can see how there is a clear linkages to armoured combat, heavy ploughs, and the need for increased hoof protection via an iron horse shoe. It is the making of the shoe, not the nailing on the horse, that links the blacksmith to the horseshoe.

ox shoes : both factory ‘keg’ shoes (thanks for correction from Pat Taylor)

An important fact to remember is that oxen were also fitted with iron shoes. In the case of oxen, the animals have cloven (paired) hoves. These have a much thinner side wall, so need considerably more care in the fitting with nails. An ox is not easily able to maintain balance on three feet, so must have shoes fitted with the animal laying down, or supported in a sling (within a suitably heavy frame).

Saint Dunstan and the Devil

From : The True Legend of St. Dunstan and the Devil
Author: Edward G. Flight - 1871
Illustration by George Cruikshank

I’m sure you all know this one - that a horse shoe, nailed above an entrance door, is good luck.

“ Legend credits St. Dunstan with having given the horseshoe, hung above a house door, special power against evil. …
Dunstan was a blacksmith and he became the Archbishop of Canterbury in 959 A.D. … was born near Glastonbury in England.

St. Dustan was one day visited by a man who the saint quickly recognized as the devil.
The devil asked him to attach horseshoes to his cloven hooves. St. Dustan did what he was told but he also explained that to perform the service he would have to shackle the devil to the wall. The blacksmith deliberately made the job so excruciatingly painful that the bound devil repeatedly begged for mercy. St. Dunstan refused to release him until he gave his solemn oath never to enter a house where a horseshoe was displayed above the door. ”


St Dunstan is also considered the patron saint of blacksmiths. ( 8 )

Like so many Christian saint’s tales, it is hard to know when this story entered into folklore. Certainly well after the death of Dustan (in 988) and most likely after his canonization in 1029 AD.

One consideration in tracing  the transition of this fable into folklore is that the original tale (oldest record being about 1125-1150 AD) states cloven hoof (my underline in the text above). As described, paired oxen shoes are quite different in both shape and use than the crescent shaped horse shoe. The country folk who would have been most like to follow the folk practice would most certainly have been quite aware of the difference. Oxen would continue in common service on farms through well into the Settlement Era, both in Europe and North America.

Any way you look at the evidence, this suggests the connection between iron horse shoes and good luck must be at the very least a Medieval invention. In absence of any documentation, I find it hard not to see the hand of the Victorians at work here?

There does appear to be regional folklore differences about what direction you position the shoe. In one, the shoe is like a bucket containing luck, so you fix the shoe open end up. In the other (notably Irish) the shoe is an endless source, so you fix the shoe tips down, so as to shower luck on all who enter.

An old iron wind chime in the shape of a horseshoe with 3 bells. 

Used as a good luck charm.
attributed to ‘Lala Love'

‘Lucky Horseshoes’ remain a stock item for gift shops, and annoyingly (because they sell), found at many living history museums. When I was the blacksmith / interpreter at Black Creek Pioneer Village, we sold commercial ‘keg’ pony shoes right in the shop.

Is this representative of Blacksmithing?
Presented with the background - I’ll let you decide.

1) Ancient Egyptian descriptions of iron as ‘Sky Metal’ is quite unlikely to actually refer to linking found iron meteorites to those uncommon streaks in the night sky. The rare finds of iron, were considered ‘from the gods’ - and of course the gods themselves dwell in the sky.
The Chinese appear to have been the first to link the sky display to found stones, later the Arabs, with the Europeans not making the connection until relatively recent times (late Medieval at the earliest) The myth in popular culture of swords knowingly forged from ’Star Stones’ is completely incorrect in making this specific connection - completely unknown to the possible weapons-smiths who might have forged Excalibur.

2) I had seen suggestions that the development might have been linked to ancient copper smelting sites located in modern day Israel. Reducing metallic copper from oxide ores takes similar temperatures and furnace designs as smelting iron. In this case the malachite contains iron pyrite impurities. Braking open the waste slag blocks often reveals small fragments of metallic iron which had also been inadvertently created. The logic goes that some bright worker thought ‘Hey, is this the same stuff that the King’s knife is made of?’ and worked to develop a method. Note that there is no clear archaeological proof for this, with the first region known to regularly smelt iron was actually modern day southern Turkey, northern Iraq / Iran.

3) A bit over stated! In ancient times, the desired result of a bloomery furnace was not hard (carbon rich) steel, but actually soft, easy to forge, iron (carbon free). The modern concepts of heat treating appear , as judged by the microstructure of artifacts, to have been developed slowly from the later part of the Roman period through the ‘Dark’ Ages. Many, if not most, Viking Age blades show almost random application of hardening or tempering (or nothing at all).

4) This may actually be ‘Industrial Age’ (i.e. post 1700’s?). The reason for enclosing grave yards originally appears to have been to keep animals from disturbing the remains. Into the Victorian era especially, the combination of a precaution against grave robbing, coupled with the decline in raw cost of iron and mass production of cast iron elements may have been additional factors. Iron fencing around grave yard is particularly a historic feature in the USA.
(I was not able to find much documentation here)


6) Much of the facts on horse shoes gathered from this article.

7) Throughout this essay :
Ancient = without written documentation, often more or less the AD / BC line
Historic = with written documentation, often with artifact evidence still important
Industrial Age = more or less post 1750
Traditional = marking a chain back in current practice, most typically post 1850



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

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