Monday, December 31, 2012

Demonstrating Aristotle at CanIRON 9

I was quite honoured to be asked by Antoine Marcal * to be one of the feature demonstrators for CanIRON 9:

(note corrected dates!)

  Trois Rivieres, Quebec

Demonstration : The Aristotle Furnace 

The Aristotle is a small sized re-melting furnace based on historic descriptions and developed by the 'Early Iron' group. It is built of clay and about the size of a standard water pail. This furnace will covert almost any iron material into 500 - 750 gram 'puck' of carbon steel in roughly 30 minutes. This makes the system ideal for those wanting to work with a bloomery type metal, especially suited to blade making. This demonstration will cover the history of the furnace and how it is built, and illustrate several operation cycles. If time permits, at least one of the pucks will be forged to a working bar.

 Workshop : Build and Run the Aristotle Furnace

Participants in this full day hands on session will each build and then operate their own Aristotle furnace, which they then can take home.
 In the morning session, clay will be prepared, and the body of the furnace will be constructed. Into late morning to early afternoon, the furnace will be fire dried. In the afternoon session, each person will run their furnace through several cycles, each producing a carbon steel bloomery 'puck' of metal. If time and equipment permits, these can be forged down (under supervision) into working bars.

This workshop is limited to six participants (adults only please). There may be an additional materials cost. No specific blacksmithing experience is required to build and operate the furnace, but working a puck into bar requires the ability to forge weld. Participants are required to provide correct eye protection (including welding lenses), and should bring their personal forging tools. Those wanting to keep their furnaces should bring a milk crate or 5 gallon plastic pail for safe transport.

 Biography : Darrell Markewitz 

'Hector's Bane' : Bloom iron with spring steel core : 2012
The very first time Darrell picked up the blacksmith's hammer was a direct result of his interest in ancient artifact and process, while a student at Ontario College of Art in the late 1970's. Objects from the Celtic Iron Age and Scandinavian Early Medieval periods continue to influence his distinctive 'Rivendale' style.

'Celts at the Gate' : Mild Steel with decorative paint : 2008
During the 1980's he worked as an artisan interpreter at Black Creek Pioneer Village in Toronto, establishing the Wareham Forge in 1992. Along with replicas for major museum exhibits, custom designs for architectural, home and garden make the bulk of his work.

'Segmented Funeral Urn' : Wrought Iron and Copper plate : 2008'Bloom Bowl 2' : Bloomery iron : 2011

As well as decades of teaching workshops, Darrell was a feature demonstrator at CanIRON 5 and Quad State 2008. He was the organization team leader for the 2011 CanIRON 8 at Fergus Ontario. He writes extensively, through on-line blogs, web site, journal articles and formal papers.
His interest in bloomery iron smelting started in 2001, having undertaken 50 smelts since. All with a focus on experimental archaeology as a means to understand historic processes. Darrell continues as a founding and core member of the 'Early Iron' movement in North America.

* Antoine is the only other Canadian seriously undertaking bloomery iron smelting. His work tends primarily to be focused on bladesmithing


Lee Sauder, leader of the Early Iron movement, will be demonstrating with an bloomery iron smelt!

Saturday, December 29, 2012

Metal Spindles?

 Or a parable about too little information - and working from photographs on the web

 The following from NORSEFOLK

1.1. Re: spindle hooks?

Posted by: "KAREN"
I have seen a photo of 3 spindles in the Dublin Museum that are from the Viking Era. They are VERY rare as the spindle shafts are made of metal, the whorls are also metal. They are so corroded I can't say if they were made by pounding or by being molded, nor can I tell if they were made in one piece or were made in 2 pieces and then fitted together.

Posted by: torran   Are these the spindles?
that was from The National Museum of Ireland.

Posted by: "KAREN"
My memory was a color photo, one of the spindles was green as if it was aged copper or bronze.

A couple of things: the image quoted is from a blog.
The blog is at :

 For the computer unskilled, if you search via google images, use the image name, you get a link over to the larger scale image - on the source blog.
If you check the profile of writer 'eimearee', you will see she lives in Dublin Ireland. I'd suggest that maybe one of you might just e-mail her via either her profile or as a direct comment on the piece. (odds are good that finding kindred souls might be of great interest to her!)

The image by eimearee
Right off the start, eimearee does not specifically say the spindles seen are metal:

 " The following photos are from the 'Viking' display, mostly found around the Wood Quay / Fishamble St area in Dublin. "
" These teeny tiny spindles are about the same length as a crochet hook; the whorls were tiny..."

 The Woods Quay site is one of those rare waterlogged locations. This results in the preservation of organics, especially at this site both wood and leather. The same conditions are extremely poor for metals preservation, especially iron.

The larger scaled image on the blog shows more details. All the images have been reduced to black and white (I suspect for file size). This may be critical for several reasons:
1) Size? You could speculate that the key numbers are the standard 1 cm tall plastic letters many museums use.
2) Material? Extremely important! If metal (at all) are they Bronze or Iron??
This will effect the overall weight of the spindles - which directly effects the thread diameter produced.
The speculation that they are metal is based on the hooks. (They might actually be wooden??) My WAG is that if these are metal at all, they are cast bronze, not iron (based on the state of preservation). The shape of #11 especially, suggests a cast, rather than forged, object. But without a wee bit more information, that is just blind speculation.

The truly serious could just contact the museum?

Thursday, December 27, 2012

5 for 'A Holding Place'

Holding Place: A Repository of Containers and Vessels by Metalsmiths Around the World

One of the axioms of mathematics is that the container must be greater than the contained. 

" The exhibition is open to all metalsmiths, professional and amateur, advanced and beginner, around the world. All metal containers and vessels are eligible for entry. Examples include, but are not limited to, pill boxes, vases, bowls, pitchers, lockets, prayer boxes and memento mori.
As this is an online exhibition the work will only be seen via the photographs metalsmiths submit. ...
The exhibition will be curated by Beth Wicker, Co-President of the North Carolina Society of Goldsmiths in the United States, and Adjunct Instructor at Northeastern Technical College in South Carolina. Director of the exhibition is Hanuman Aspler, owner and founder of the Ganoksin project, the world's largest internet jewelry site. "

Artist's Statement:
Since the late 1970's, I have been blending experience at the forge with research into the artifacts of the ancient Norse and Celts. The result is my signature 'Rivendale' design style. My work places a strong emphasis on hand forged techniques into distinctive designs, creating one of a kind objects that are both beautiful and yet functional.
For 'Holding Place', I have selected a series of bowls that use the widest possible range of iron materials, from modern steels, antique wrought iron to my own unique bloomery iron. Coupled with a range of hot forming techniques, ancient, traditional and modern, I believe this range of work may stand apart from other submitted objects.

1) Segmented Funeral Urn (2008)

38 cm x 23 (17 kg)

The body of the urn is composed of a number of individually hand forged strips of antique wrought iron. I saw samples of a related technique employed by the Japanese blacksmith Takayoshi Komine at a workshop / demonstration two summers past. (Taka uses the method to make subtle oil lamps employed in the Tea Ceremony.) Actual historic wrought iron has been chosen for the construction because of its excellent forging characteristics and special durability. Individual scrap bars were selected for their tendency to fragment under aggressive forging. The metal itself is already some 150 years old — and should easily endure for centuries more. A fitting resting place for the memories of one past beyond us.
(see more)

2) Segmented Bowl 2 (2011)

22 cm x 18 x 9 H

The individual segments are pieces left over from torch cutting 1/8 inch thick plate used for another sculptural form. Taking a clue from a method used by Japanese artisan Takayoshi Komine, the individual segments were MIG welded together on the back. One of these weld lines was reversed, folding forward to make the central rib.  The resulting flat form was then worked hot to dish it. To finish, the piece was sealed with a spray matte varathane.

3) Bloom Bowl 2 (2011)

(roughly) 25 cm x 15 x 15 H

Unique in Canada, this metal itself was made from raw ore smelted using a direct reduction furnace based on those from the Viking Age.
The original bloom mass was quartered by hot cutting. This section was flattened under the air hammer, working at welding temperature. Only one compaction series was undertaken, intentionally to allow cracks and fissures to develop along the margins of the plate. The roughly rectangular plate was then dished hot to create the bowl's shape. The inner surface was roughly polished with a flap sanding disk. The outer surface was given a fast wire brush to remove any loose scale. To finish, the piece was sealed with a spray matte varathane.

4) Offcut Bowl (2011)

25 cm x 25 x 15 T

Offcut Bowl was created for the 'Shadowbox' show to benefit the South Grey-Bruce Literacy Council.  The individual segments are in fact off cuts left over when I was cutting up some 1/8 inch thick plate I acquired as commercial scrap. The individual segments were MIG welded together on the back, then the weld beads ground smooth. The resulting flat form was then worked hot to dish it.

5) Segmented Bowl 3 (2011)

16 cm x 12 x 9

Here a set of individual strips of flat stock were forged out from heavier bar. This hand working process results in variations in thickness and width between the individual pieces. Once forged and cut, the strips are MIG welded along one side only, which is then ground smooth. The resulting plate is then dished hot to create the bowl form. The stretching of this dishing separates the lines between the individual strips, which are still held tightly by the welds.

Full descriptions of my past work on bowl forms : 
Can be found on the Wareham Forge

Wednesday, December 19, 2012

'Stretching Hammers' - Viking Age

On 21/11/12 6:54 PM, Richard Furrer wrote:

What are the dates on these tools?

number 21 in particular.

(Ric pulled the image off an earlier blog posting. There is a more detailed image, with a bit more information, on my disk 'Exploring the Viking Age in Denmark'.)

The labels at the Roskilde Museum were fragmentary at best. What was there was also in (surprise) Danish.

The case section was labelled 'Lejre 900 BC - 1000 AD'
My only notes on that group say 'Hammer head on left 3 x 3 cm by 10 cm long'
Lejre, by the way, is just to the west of Roskilde. There is a very excellent  archaeological research and living history site there.

One of the things to remember is that in Scandinavia, there is not the same definition of 'Viking Age' as is used in the English speaking side. To Danes, there is an 'Iron Age' - then 'Medieval', with the break at 1000 AD.

About life size - from "the Mastermyr Find' Arwidsson & Berg 

There is a similar hammer found in the Mastermyr Tool Box (Gotland)
Number 68, described as a 'stretching hammer' (and I would agree, having made and used a replica).
3.0 x 2.1 cm by 14.8 cm long - weight at 481 gms
Note that the Mastermyr set has been recently re-dated to closer to 1150 AD.

As this puts the two tools in roughly the same weight class - and that at the very bottom end weight for forging iron, I would suggest the Roskilde Museum sample is also intended as a tool for deep dishing - maybe for bronze cauldrons.

PS: Frequent Readers may notice the pattern here. I often try to respond to e-mails with rather long replies. These however often get modified and turned into blog postings. Just a word to the wise...

PPS: It has been a month since I prepared this piece, for some reason I have not been able to get it actually published to the blog (???)

Iron to Wire? Some considerations on materials.

 As frequent readers know - I do spend (too much?) time every day on detailed answers / comments to various questions that come into me via e-mail. These pieces would be 'lost' if only sent to one respondent, and so often are modified to become the meat for postings here....

On 17/12/12 1:00 PM, Stephen **** wrote:
My interest is in replicating historical wire - iron, steel, and brass - for musical instruments. The research is done as part of my work at (named University), but it's also practical in the sense of replicating it for a niche market. I'm already selling iron wire and investigating the other materials. As you can imagine, production economics is a nasty constraint. A big problem is getting from cast ingots to rod stock. Historically this would have been hot worked by powered tilt hammer, which is probably not economically viable nowadays even with access to appropriate equipment. The wire drawing operations push up the $/kg production cost of the finished wire so there isn't a lot of $ room in the heavy stage production of the rods. I came across your 'bloom 2 bar' project and wondered what practical solution you might have come up with for converting your bloom iron to bar.
A couple of things in your message:

"I'm already selling *iron* wire"
Since you are being specific, I take it what you really mean is a modern Bessemer produced low carbon content *steel* wire. 'Black Iron' fencing wire one possibility. Getting 'soft iron rivet' material is another. A third would be the use of 'Electric' or 'French' iron. (All these are NOT the same as historic wrought iron material.)
I drone on about this endlessly, but actual *bloomery* iron / *wrought* iron is no longer available in commercial production. I have seen some hints that smaller amounts might be under production in China - but only as a material for specialized blade replicas. Other than that, these ancient / historical methods are only employed in very small scale - by people like me
(demented wackos) .

"historically hot worked by tilt hammer"
Most modern day professional artisan blacksmiths will have some kind of power assisted hammer in their shop. These fall into mechanical or air driven types. This does allow for the working of more massive bars.
I have both a 30 ton hydraulic press, designed for initial bloom compaction, and a 50 lb throw air hammer in my own shop for example.
The problem is actually on the other side - small diameter bar into wire. Few have the special equipment (or specific skills or experience) for drawing wire. I certainly have never done this.

"selling iron, steel and brass wire"
Wire of various copper alloys (tin and zinc alloys) is certainly available. A problem might be getting small enough order quantities against your business volumes.
*Steel* - as in modern produced simple iron plus carbon alloys will also be available in almost any combination you might require. I expect there that the purchase sizes may be much smaller, although some hunting might be required to find just what modern business might sell small amounts of exactly the specific alloy you might want. (Auto repair for example)

As you certainly are aware, actual *bloomery / wrought* irons are distinctive in their physical composition (this separate from alloy composition). They will contain some level of hard glassy slag, if only at a microscopic level. This will effect their mechanical properties, I suspect in ways that might be critical to your application as drawn wire in musical instruments.
These materials are also not consistent through their volume - the way modern industrial steel alloys are. This likely presents a huge problem for your specific application.

This all represents a major terminology problem - one that is not dealt with effectively (to my observation) by museums and academic researchers. "Steel" is used generically for any iron plus carbon alloy - reguardless of its method of production or physical structure.
In working from a natural iron oxide source ore into a working metal bar, there are effectively *three*  different factors that might effect the characteristics of the end product.

1) How the iron oxide was physically reduced down to a metallic iron mass.
This is the type and individual design of the furnace, related to the method of production, modified by the specific ore itself. Experience and skill of the iron master comes into play here.

2) How that iron mass is physically manipulated in secondary processing after it has been created.

3) The actual alloy chemistry of the starting mass, as potentially modified by the secondary processing. Primarily the single largest variation comes through changes in the carbon component of the metal.

In short, depending on the starting iron ore, different furnaces may produce different products, both physically and chemically. How the iron master controls the iron smelting sequence can also modify both.
It is quite possible to get radically different carbon contents from the same ore (even in the same furnace).
The resulting mass can then be manipulated in different ways during the 'bloom to bar' process. This may change physical structure and carbon content.
Carbon can both be removed, but also added during secondary or tertiary forging processes.

Often historic bloomery iron materials were effectively impregnated with additional carbon through surface diffusion. You can see how this would produce a material with a layered texture, including some degree of slag filaments, which then varied in carbon content from a higher C exterior fading to a low C interior. Compressed into a wire, this might seriously effect the performance of that wire musically.

I refer you to Lee Sauder ( A close friend and fellow researcher - and easily the most skilled bloomery iron master in North America. Lee also does sell both raw bloom sections and blooms worked to billets.

Sunday, December 16, 2012

IS there Iron? - Part 3

As a refresher, this is a continuation of the series report on field walking in November. Generally not a bad time for this, the vegetation has died back, the bugs are gone, the water levels often lower. This year (despite claims by fools in America) the impact of global climate change (and Canadian warming) was clear. Mid November and still no snow!

IS there Iron - Part 1
IS there Iron - Part 2
North Erie Shore - Bog Iron

Take a look at the map of the region around Wareham again:

10 km range circles
Location 1, Bellfountain, was discussed in Part 2.

A couple of days later I had occasion to run up to Collingwood (look NE of Wareham, along Georgian Bay). On the way back I ran on a rough diagonal line back to Wareham, more or less along County Road 32. This lays along a valley cut into the edge of Blue Mountain. Note that Blue 'Mountain' is really the slope of the edge of the massive limestone block of the Niagara Escarpment - not a true 'mountain'. 
I did see at least one spot that looked like it was at least worth a closer examination when seen from the road. This was a very sharp cut of a stream bed that exposed the underlaying rock. Massive problem however - hunting season! It was late afternoon, and the road was dotted with trucks unloading men in orange jackets with rifles. (I was furious at this, the area was well sign posted as being provincial park land - 'No Hunting' signs all over.) I most certainly was NOT going to chance leaving the roadway!

Location 2 - Chepstow

A week later, I paid a visit to my close friend David Robertson, who had seen potential signs of iron south of his home / shop near Chepstow (look to the far west side of the map).

The spot was a rock cut into a shallow valley, which had a swampy bottom with a small stream running through it. David's thought was that this bottom land might contain bog iron ore, deposited from what he thought looked like iron contained in the surrounding rock.
On closer examination, the staining on the limestone was in fact a reddish yellow clay deposit, washing out of the stone. Although the colour was likely do to traces of iron oxide, there was only minimal amounts of iron present. Certainly not enough to constitute a useful ore.
(And truthfully, it was absolutely pissing down a hard cold rain - we were soaked to the skin in the five minutes at the rock cut alone. Retreat for hot wiskeys was called for!)

Location 3 - East Owen Sound.

Another place where the parent rock of the Escarpment is cut through is at Owen Sound, about 45 minutes drive north of Wareham. About mid November, I had to run up that way for steel supplies. I drove over to the east of town, where again the rock is exposed. I ended up not getting out of the truck for a closer look. The stone was very similar in appearance to that seen in the image above - a light yellow porous limestone.

Location 4 - East Markdale

On the way back home, I travelled down via a series of dirt roads more or less straight south from the Owen Sound area. The table of the Dundalk Plateau is cut by a number of deep river valleys (originally glaciers) through that area. The Beaver Valley is the one just to the north of Wareham, running SW to NE, from roughly Flesherton towards Thornbury on the map.

(Sorry about the image quality on these next)

Limestone at the edge of the valley cut
Tumbled blocks at the foot of the cliff
As you can see from the image, the stone here is a more solid, hard, dark to medium grey limestone. There was no evidence of iron staining at all. Although the heavily moss covered rocks were quite magical in appearance, there is no iron present.

Friday, December 07, 2012

December 7, 1941

Photo #: 80-G-19942

Pearl Harbor Attack, 7 December 1941

USS Arizona (BB-39) sunk and burning furiously, 7 December 1941. Her forward magazines had exploded when she was hit by a Japanese bomb.
At left, men on the stern of USS Tennessee (BB-43) are playing fire hoses on the water to force burning oil away from their ship

Official U.S. Navy Photograph, National Archives collection
 Image loading from :

Pearl Harbor Raid, 7 December 1941
Overview and Special Image Selection

Sauder's Standard Test

The following was posted by Lee Sauder on to Facebook. As frequent readers here know, Lee is largely responsible for the Early Iron movement in the USA (and a close friend). I have stolen his posting to the 'Iron Smelters of the World' Facebook group to help spread his suggestion.
 Since Mark (Green) brought up the twist testing, I thought I'd you tell my way of doing it. I've been testing blooms this way for a couple of years- the nice thing about it is that you not only get the subjective feeling of the iron, (which is easily confused or forgotten), but there's an easily quantifiable record as well-- how many twists it takes before it fails. I've found this very helpful to understand what I've done without expensive chemical analysis, which isn't really as meaningful as how tough the iron really is. I like do do this with the bloom hot right out of the smelt, so the test is still connected with the memory of the smelt.
Sectioned bloom and ancony with twist test.
If we all did this in a similar way, we'd have a better way to compare and communicate our results. Here's my way- could I propose this as a standard to communicate with?

I originally did both hot twist tests and cold twist tests, but now I usually just do the cold twist test, which seems to tell us the most. I forge the bloom to a bar approximately 5/16 inch ( 8 mm) square, (with no folding). Let it air cool. I mark off 1.5 inches ( 38 or 40 mm), and twist it until it breaks, counting the quarter turns.
Close up of twist test
 My low-carbon, high phosphorus blooms break at zero to 1/2 twist, with a crystalline fracture. The low-C, low P blooms go 3/4 to 2 twists- the best we've done so far did 2 full twists, the one shown in the photos.
Ductile fracture at 2 complete twist.
Crystalline fracture at 1/4 twist.
 The hot twist tests I do by forging to 5/8 inch square, marking off 3 inches. heating to yellow. and twisting to failure. The higher P ones actually tend to twist farther hot than the low P ones. Usually in the neighborhood of 3 to 4 twists before it breaks.
I actually have never done this with high C bloom, so I don't know how it acts.

I think this is a great way to judge your iron in your own shop.

The images and text above all by Lee Sauder

Sunday, December 02, 2012

About Replica Silver Pennies

Preparing to strike a coin - at the Althing Event, 2011 (image by Tanya Imrie)

... I found your group through a mention in an
SCA event notice.  I see that you demonstrate
coin minting.  Are the coins copies/replicas of actual historical coins
or are they your own design made in the style of the era?

See :

There were four individual artifact coins selected. Three were used pretty much as the original source material designs. The fourth 'Knute the Great' was used as the source of the general layout, but the name was changed to my own.

This makes four individual dies. Note that these are four different coin artifacts - and were selected for their graphic quality.  I will often mix and match those dies to produce different combinations.
Artifact coin dies - York, England, early 900's

The dies are in two pairs. The first set (St Peter / Anlaf) are simple cylinders of tool steel. For the second set, I forged the die blanks to duplicate the shape and size of the pair found at York.
Dies shaped after the York artifacts on the left. First dies made of tool steel on the right.

The silver used are modern die cut disks - so extremely uniform. These are sterling silver. They are the same size, thickness and weight as the 'standard' silver penny.

Replica 'St Peter' / 'Anlaf'
Replica 'Knute' / 'Birka Grave'
The dies were acid etched to create the patterns - not engraved as the originals were.

Now, two major differences from the original source coins were made - and intentionally.
1) the main figure on each coin is mirror image from the artifact
2) the dies were made to make an impression into the surface - not create a raised line like the artifacts
Both of these methods were used to clearly indicate that these are NOT possibly forgeries. Combined with the obvious uniformity of the silver disk, that creates 'three points of difference'. As there are currently hundreds of these replicas out in the world, I wanted no chance they might be artificially aged - and passed off as original artifacts.

To my mind this makes the silver penny replicas I make ideal for hands on programming in museums, or use by living history re-enactors.

Thursday, November 29, 2012

Furnaces with Shells?

(This is repeat of a contribution I made to an ongoing discussion over on Don Fogg's Bladesmith Forum...)

What appears under consideration here are thick walled furnaces, with an eye to increasing the durability of the structure.
I have worked a lot with various cobb mixes - blends of clay / sand / organics. Our (DARC) basic design here has been primarily chopped straw plus clay. I have built a lot of furnaces, as our primary investigations have been with various archaeological models.

From conversations with Lee Sauder, my understanding (??) is that the addition of sand to the clay increases the resistance to temperature of the finial wall material. Most importantly, the sand does not expand with heating near as much as the clay will, thus making the walls more stable at smelting temperatures. Careful drying of the constructed furnace is critical.
(A reminder to new readers - as water heats it expands as steam - something like 50 times the volume. If this steam does not vent slowly, cracking, even explosive spalling, is the result.)

Straw cobb works in a different manner. Our most typical mix starts with 50 % dry potters clay / 50% straw by volume. Add maybe an additional 10 - 15 % sand to stiffen the mix. The straw is chopped to roughly 10 cm (4 inch) or less pieces.
The individual pieces of straw in the mix carry out several functions:
- Being hollow, they give the steam someplace to expand into, reducing cracking effects.
- As the inner surfaces of the furnace reach smelting temperatures, the straw burns out. This leaves hollows in the clay matrix - in effect acting as an insulating layer. This actually does increase the overall resistance of the wall to high temperature.
- The outer layers of the furnace, although hot, are not high enough to burn away the straw. So the straw acts like pieces of rebar in concrete. Even if cracks will develop, the straw binds the gaps - holding the walls together.

Generally I would say that the high sand furnaces Lee builds (PDF) are more durable over the long term use. I think he had one furnace that ran over 35 individual smelts. The down side is that the construction requires considerable care and time to undertake correctly.
The use of the clay / straw cobb allows for much quicker construction. I have certainly done a build in the morning, then fired in the afternoon. I would generally say these furnaces are not as durable. The most we have used one furnace has been five smelts. This is more because of our climate in Central Ontario, working in an exposed smelting area. Clay cobb is much more susceptable to damage through the freeze / thaw cycle (mainly because of those internal voids). (Our normal pattern here is three smelts a year, June / October / November, so almost every furnace sees at least one winter cycle.)

Something Michael Nissen (from Ribe in Denmark) showed me when I visited with him in 2008 - the use of shredded horse manure as the organic mix. This results in a much finer texture to the cobb. It does still retain the heat resistance and strength of the straw mixes. Gather old horse pucks, which shred easily when rubbed between your hands. Mix 50 / 50 with the powered clay. I have not used this for a complete full sized furnace. It has become my standard mix for the smaller Aristotle re-melting furnaces, where it shows great refractory ability. Michael (at that point) was using a 'bellows plate and blow hole' system. This features a roughly 15 x 20 cm thin plate set into the front of the furnace - with a hole in it through which the air is blown. This is hottest part of the furnace wall, yet even 1 cm thick plates of horse cobb have demonstrated great durability.

I have constructed a couple of furnaces in metal shells.
One was a variation on our 'Econo Norse' brick teaching furnace. I managed to scrounge a 1/2 sized metal barrel (20 gallon) from the dump. This was used as an external shell for an arrangement of standard fire brick set in a hexagon pattern, three bricks tall. The gaps in the pattern were held in place with a mix of clay and sand - as much as a binder as anything else. Although heavy, the size is such I can lift the completed furnace by myself. The solid metal shell allows this furnace to be portable. The ideal way to use it is in combination with a concrete block plinth, packed with ash / charcoal fines (learned from Lee & Skip). See the smelt report : http://www.warehamfo...eport04-08.html

Last spring, I built a variation on Lee's successful design. This was his suggested mix of 50 clay / 50 sand. I had an old metal garbage can, which proved just the exact size required with the bottom cut out and turned upside down. At this point this furnace has only been fired once - but it remained in almost perfect condition after the smelt. You'll see in the image below it also uses a forged copper tuyere - again prototyped by Lee.
I thought I had a close up of the shrinking of the clay walls. Although I used the metal can as an exterior form, buy the time the furnace was completely dried with an internal fire, there was about 1 cm shrinking all around. Thats with an internal diameter of 25 cm and wall thickness of 5 cm. My mix was 'looser' than what Lee uses, so much of that volume might have been the extra water (??). This furnace is set on a circular brick base (again stolen from Lee). The intent is not to make the furnace portable, but to protect the walls from the effects of rain and more importantly Canadian winters (!). I have covered the entire thing with a old plastic 45 gallon drum for the season. See : http://warehamforgeb...tion-smelt.html


PS - sorry about the order of the images - I pretty much pulled them down as I thought of it.
1) Three older furnaces, set out as an experiment in aging / weathering. The two at the rear are both clay /straw cobb construction.
2) My new Sauder style 'production' furnace, before firing.
3) Michael Nissen's furnace at the Heltborg Symposium, 2008. Body of straight dug clay, inset horse manure cobb bellows plate.
4) The 'Econo Norse in a Can' furnace - before firing

Attached image(s)

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Wednesday, November 21, 2012

Is there really a need for this forum?


Archaeometallurgy forum 

Forum for all aspects of past metallurgical activities

 A new discussion group, started by Bastian Asmus in early October.

He posed the question : Is there really a need for this forum?
When I posted in the Jiscmail list that I had started this forum I had some answers both privately and online if there really is a need for another resource.

I think that this is a good question and would like to discuss this in earnest.
The main criticism I received is that there are already too many resources available and that other, already existing social media could be used to achieve the same effect. By creating another one it is one more resource to have an eye on..
 The following was my contribution to that discussion :

There has been an evolution, as the internet as evolved, in this medium as a communications tool.

I may be able to make some bold (!!) observations, having been involved in metalworking aspects of using the internet since pretty early on:

At first it was the discussion boards? (Remember those?) Kind of like the live chat that you find associated with Facebook these days. Slow, so slow. Pretty much wide open. A bit like trying to talk at a party - everyone saw, anyone could drop a line in. Often frustrating because it was so slow in the transmissions. And no records kept at all of the conversations. You might be able to cut and paste out pieces into a file - but generally once sent, things were gone. You also had to almost find specific individuals by accident - you all had to be on the same board at the same instant to converse.
I was actually surprised to be able to find others interested in historic metalwork at the time (be the early 1990's). Having a group of people working on the same processes and source artifacts was amazing. And world wide!

Into the 90's - it was individual web sites. The amount and quality of the information presented varied a huge amount (and still does). The biggest problem (and still) is maintaining web sites over long durations. My own site has been at a stable URL since the mid 90's - and this is unusual. The huge advantage that with a little work, any individual could now publish information. For those of us working outside the academic stream, this was very important. Of course *quality* of information was very irregular (to be generous).

I was part of the group in North America, largely started by Mike McCarthy, lead by Lee Sauder & Skip Williams, behind 'Early Iron'. First several conferences, then an documentation web site ( This never became as useful as it might be - largely because of the huge amount of work involved trying to manage the (yet another!) web site.
Attached to this was the original Early Iron discussion group. At one point it had something like 200 plus involved, world wide. The international aspect was its biggest strength, attempting to tie together what was happening in Europe with what was developing in North America. As such groups do, the interest would wax and wane. Tied to geocities / yahoo, there were problems with the access via e-mails. This was ideal for some, not so wonderful for others. It did allow for an archive of past postings.

More into the 2000 period, personal blogs became active. These are driven by interested individuals, so often can be fairly detailed in the amount of information included. Not necessarily the easiest to find, but generally a google search will yield topics of your interest. The best are fairly narrow in focus. They all suffer from limited volume. Most importantly they do not allow for easy discussion, but only represent a single viewpoint.

Don Fogg's Bladesmith Forum has become of late a very active discussion. This is largely because of the developing interest by practical, mainly American, knife makers in bloomery type materials. Some of the main voices in developing the techniques experimentally have become active there. The truth is that there are two quite different approaches developing. The earlier workers were very much concerned with *process*, many of the 'second generation' concerned with *product*. (My view at least.) This forum does allow for easy posting of images, and does maintain an easy to source archive. (The format is the same as what is being started here.)

Enter Facebook. 'Iron Smelters of the World' - Mark Green has been largely responsible for developing that venue. It has the advantage of being extremely casual. It has a certain ability to allow images. Its huge drawback is that it only allows for the shortest of text. It is often hard to follow single topics. There is preservation of the threads, but no easy way to sort or search those. Certainly something that has been extremely active, and pulls in a large number of people world wide. There are also a number of experimental archaeology FB pages available. Although there is much specialization easily possible, the truth is that FB is simply too fragmented.

When I was talking to Lee Sauder about this new discussion group, he did point out one of the greatest potential strengths. Of being able to hold information - search it - and allow for longer, more detailed postings. Of allowing for serious *discussion*, hopefully with a collection of academic researchers, skilled industrial people, experienced practical artisans and serious amateur researchers.
I have to agree with Lee (and echo Alan) that a blend of the 'rubber boot' archaeologist and the working metalsmith may prove the most fruitful. I have hopes. But I do notice there are a lot of 'views' here - and not that many submissions yet...

Sunday, November 18, 2012

North Erie Shore - Bog Iron?

On 17/11/12 10:24 PM, Jonathan Martel wrote:
... I've been doing some research on bog iron in Southern Ontario and came across your blog posting from 2009.  I was wondering if you've had any luck since then in your search for bog iron sources?

Short answer - no.
If you search for 'bog iron' on the blog, there must be several dozen articles altogether. The 2012 searches in Newfoundland may be of most interest (with images of signs in a bog). You will also want to take a look at the most recent postings - describing some field work in West Central Ontario over the last couple of weeks.
The exact chemistry and geography that is required for a *workable* deposit of primary bog iron ore is very specific. There are a couple of possibilities in mechanism too. This is complicated by the fact 'bog ore' is a term that is used by almost everyone - but for radically different materials with quite different deposit methods. In short, if there is iron ore found any place near water, it gets called bog ore - regardless.
To complicate this, deposits may be from ongoing formation - or an ancient deposit, now uncovered.

I've found some historical sources indicating that bog iron was historically smelted in Essex and Norfolk counties.  Do you know if ore exists in any quantities whatsoever or have they largely been tapped out and not at all worth while?

Jonathan is referring to deposits - and furnace operations around Normandale Ontario, on the north shore of Lake Erie. See : 
Link to the Ontario Historic Plaques information with a location map :

Those deposits were largely mined out in the middle 1800's . There were most certainly ongoing deposits in boggy / swampy ground around that area (Normandale - 1820 - 40 roughtly). These supplied both blast furnaces for cast iron, and also larger bloomery furnaces for making wrought iron bar.

Problem was two fold:
First, Victorian era iron furnaces are large, and require a large amount of ore to function - and a huge amount of charcoal to fire them. This demand quickly outpaced the natural production cycle of the primary bog iron ore. Net effect was the naturally 'stockpiled' material from ages before was quickly consumed.
Second was that the combination of clearing land for farming and cutting timber for charcoal production was coupled with the draining of swamps for fields. Combined, this altered the local geography, in effect destroying the swamps and bogs required for the chemistry of iron ore formation.
So in effect the limited natural resource was quickly consumed, while the landscape was altered to reduce the possibility that more natural ore could be formed. Commercial production in the Normandale area operated at best for a decade or two, before being abandoned.

No I will caution this next remark with saying that I have not personally walked the ground in that area. I have been told from those from that region (south of Brantford) that with the tensions between the First Nations groups and others - and troubles over land claims, that often local residents are not keen on unknown strangers walking their fields.
That being said, I have seen a sample of reported bog iron ore taken from the area. Of course there are all the problems with a sample gathered by someone generally interested in local history, but not with any personal experience with bloomery furnaces. Did the sample represent the kind of ore actually used in the Normandale furnaces? Or was it a piece considered too poor, even at that time, to be harvested and used?
Anyway, the sample contained a considerable volume of sand and small gravel. On a guess, I would say well over 50% of the volume was these impurities. It was hard to tell how much iron oxide was actually present in the roughly fist sized piece I was shown.
Certainly if that sample was representative of the modern day available iron ore, it would not be suitable for the kind of small size bloomery furnaces we are currently using. (Our Pre-1000, Northern European style furnaces require about 50% iron content (or better) to be truly effective.)

Note to Readers!
I certainly would love to be proven wrong on this! If your own field walking in Central Ontario discovers anything that looks like a purer primary bog iron ore, I would be most interested in knowing about it.

Friday, November 16, 2012

Is there IRON? - Part Two

(You are encouraged to first read the background article 'Is there IRON in these hills?')

First, remember the physical size of the Niagara Escarpment:

Now, take a look at the Ontario Roads map of the region around my home base in Wareham:
West Central Ontario, range circles (10 km) centred on Wareham

Did I say FLAT? What the ground around here looks like!
Over the late Fall, I have made a couple of trips that have included looking for possible iron ore sources. As I explained in the earlier posting, I really had no expectation of finding anything. But as my friend Lee Sauder (wisely) told me 'You ain't going to find anything - if you never look.'
I felt the only hope of finding anything at all would be at one of the rare places where erosion had exposed the base limestone of the Escarpment.

Four locations are indicated (yellow circles) on the map above, in the order I looked at them. For each I was looking for places where the under laying rock was exposed.

ONE - Belfountain

This point, just south of Orangeville and west of Highway 10. is where an ancient river had cut through the loose gravel cover to expose the limestone. There was enough water moving originally to both cut the rock, but also to throw refrigerator sized blocks around. Today there is a waterfall down one exposed face of this cut.

From the waterfall, we travelled about 200 m down the path that runs along the top of the cut on the north side. Eventually this trail runs down to the bottom of the cut. 
One feature there is a pile of larger stones, obviously cut from further upstream at some point in the distant past. These have been tossed into a pile along the south bank, in a fairly localized area. It looks like the force of water could carry them this far, but no further. These blocks are of a different limestone than those in the rock cut at the same area.

Showing the limestone face, part way up the pile of jumbled rocks (to the right here)

Kelly standing beside one of the large rocks showing iron staining
Iron staining on rock surface - bag is 4 1/2 inches
Iron staining appearing to form a line through the pile (?)
I was greatly encouraged by this - but this was not a source for ore!
On closer examination, what was happening was that these rocks had a smaller amount of iron contained within the matrix. As the water seeped into the stones, then later evaporated from the surface, there was a small amount of iron forming like a scale on the very surface. Although I did flake off a couple of fragments as samples, it was clear that the 'iron' was only a thin film on the surface. At best only one or two mm thick. More like pulling off a surface layer of rust flakes.

(Stay tuned for part Three)

Sunday, November 11, 2012

Some always Remember

I normally wax philosophical for Remembrance Day. Although I have less 'time on the ground' than some who will read this , I do know my soul understands what my body had not experienced. That balance between the high ideals that drive and in the end preserve you, against the futility and raw terror of the action. All those statements of truths we knew, even young, but never really understood as now perhaps we now do. Of seeing the cycle endlessly repeated of 'Rich old man's war, Poor young man's fight'. Yet another generation of cannon fodder shoved into the meat grinder, only for the benefit of a mere handful of the Powerful. I don't think I have become wiser, but it seems more extreme and more obvious to me every conflict.

And so the Boys come Home. For a while.
We all know, in the darkness of the night, that this is just a pause in the endless cycle. This War will pass, like those before it. Certainly soon to be replaced with another Conflict. Those that sat behind desks will thump their chests and speak of Glory. Broken down veterans with empty eyes will be disreguarded on the street. Civilians will speak of the horrors, never considering the cost others paid for the soft lives they possess. Ever more Citizenship will be equated with Rights - never Responsibility.  Another generation will forget or disreguard the lessons so bloodily bought by the few.

I will raise a glass here, at that agreed upon time.
But this year, darkly...

Thursday, November 08, 2012

African IRON - on YouTube

There are some available documentries of the last traditional iron smelting in Africa. These were recorded back in the late 1960s - early 1970's. Preview clips have recently shown up on YouTube:

Inagina: The Last House of Iron

Swiss archaeologist Eric Huysecom and cameraman Bernard Augustoni work with 13 master smelters to recreate the building of a traditional furnace for smelting iron in Mali. There has not been any traditional iron smelting in Africa since the 1960's, in part due to the importing of cheaper substitutes. The building of the furnaces and the work involved in the actual production is deeply entwined with ritual, symbolism and gender. This film describes in great detail every aspect of the event, from the selection of the site of the reconstruction - which is the oldest remaining furnace site in the region, last active in 1961 - to the final result. This is an important film for African Studies, Archaeology, Religion, Ritual, Technology and Gender.

a film by Eric Huysecom, (Geneva) and Bernard Augustoni
distributed by Documentary Educational Resources. Purchase:

The Blooms Of Banjeli

The Blooms of Banjeli documents research in Banjeli, Togo on iron-smelting technology, its rituals, and the sexual prohibitions surrounding it. Including rare historical footage from the same village in 1914, it provides a unique technological record of the traditional method of preparing a furnace to smelt iron. This documentary offers an interesting approach to our understanding of the relationship between conceptions of gender and technology in traditional African society. The people of Banjeli liken the furnace to a woman's body, which is 'impregnated' by the smelter. The process of smelting is compared to that of giving birth, the furnace being the womb and the iron bloom, the newborn. a film by Carlyn Saltman with Candice Gaucher and Eugenia Herbert distributed by Documentary Educational Resources. Purchase:

Tuesday, November 06, 2012

Is there IRON....

... In them thar HILLS??

Or maybe not.

Although Iron, as iron oxide minerals, is one of the most common found on the earth, as anyone actually LOOKING for the stuff knows, it is really not that easy to find as usable ore.

An added complication is that those looking for iron ores for use in direct process bloomery furnaces need to have ores in concentrations far in excess of that which modern industrial processes can utilize. Ideally, the small Early Medieval furnaces that I am interested in require iron concentrations in the order of plus 50% for effective bloom creation.

- After centuries of human activities, many of the best ancient deposits of suitable iron ores have been already used up.
- Although primary bog iron ores have a continuous deposit process, the sad truth is that the exact chain of geology and geography needed to create concentrated deposits is very specific. Even small amounts of human activities can completely disrupt this formation chain.
- In many cases the reason ores may still remain in areas once exploited in the past is simply that those individual pieces of ore are not of high enough quality to have been utilized the first time around.

Obviously my first question would be 'Is there any usable iron ore locally?'

I live close to Dundalk Ontario, abut 2 1/2 hours drive NW of Toronto. On top of what is called the 'Dundalk Plateau', an area about as flat as a pancake:
The Niagara Escarpment is recognized as one of the world's unique natural wonders. Essentially, it is a landform -- a ridge of rock several hundred metres high in some locations -- stretching 725 kilometres (450 miles) from Queenston on the Niagara River to Tobermory at the tip of the Bruce Peninsula. Today, in Ontario, the Escarpment contains more than 100 sites of geological significance including some of the best exposures of rocks and fossils of the Silurian and Ordovician Periods (405 to 500 million years old) to be found anywhere in the world. 
from the Niagara Escarpment Commission web site 
Range of the Escarpment - Altered from Wikipedia
So - lets consider the ground around Wareham - my base in Central Ontario:

What this all means is that Wareham sits near the top edge of a gigantic, flat, thick, slab of solid limestone - a block a hundred metres thick. This was buried under plies of loose sand, clay and rock in later ages. About ten thousand years go, a wall of glaciers bulldozed off most of this loose stuff, filling in most of the cracks and pretty much scrapping the top off - leaving the landscape even flatter. There are some places around the edges that in the centuries since, rivers have washed out the loose materials, sometimes even exposing the top edges of the under laying limestone slab.
One feature of the remaining top cover over the solid stone plate is a bank of clay, roughly 10 - 30 metres thick. This is a fine red clay, those that remember 'Blue Mountain Pottery', popular in the 1960's and 70's, know the stuff. This layer effectively seals the aquifer inside the limestone from the surface collected water above. 

There are no exposed rock faces close to me. There are large valleys which cut into the plate of the Escarpment, to the east and north of Wareham. There are very few places the rock of the Escarpment are actually exposed however. Those valleys have sides covered with massive piles of loose sand and gravel. (Of course the flat areas around have farm fields on them, the contours of the valleys covered with combination maple and pine forests.) Getting to those valleys is a roughly 50 km / half hour drive north, closer to 30 km / 20 minutes to the east. Spotting any place where there is exposed rock is extremely difficult.

Now, our well at Wareham is a deep one (175 feet) down through the clay layer and into the aquifer of the Escarpment limestone. There certainly is iron dissolved in that water. It cloggs our coffee makers and even settles out as a thin film of fine red iron oxide if you left a container to stand overnight. Remember however the *surface* water is sealed off, entirely separated by that thick clay cap over the limestone. (Its why you pay for a deep well to begin with, as the surface water level fluctuates hugely over the course of the seasons!) So if there is elemental iron oxide in the deep water - it is only going to come close to the surface at locations where the base limestone is exposed. 

I certainly have wandered along the margins of creeks and swamps around Wareham, looking for possible primary bog iron ore deposits. A couple of places, I have spotted very marginal signs of a red iron ochre in the water. Never anything like an amount that could be collected, much less a deposit of actual bog iron itself. This is suggestive however, at least of the possibility.  
There are a couple of operations in the area that dig 'peat' - which in this case is really the organic rich sediments from the bottom of the swamps. These are not true peat bogs, with their chemistry of tannic acid. As these swamps are basically water filled pits into the under laying clay, there is no ability to leach elemental iron out of the rock underneath (this even assuming there is available iron in the rock itself).

Maybe along the slopes of some of the valleys?

(stay tuned for part two..)


Friday, November 02, 2012

Iron Smelt in Russia?

 (This is a much older piece that got caught as a draft somehow and I think never posted...)

This video clip was suggested by one of the Early Iron gang:

The clip shows a team from Russia (given the Cyrillic text) working at a large living history (Viking Age?) event.

I quite like the simplicity of the basic construction method. Use of bundled straw for interior form is elegant.

I do wonder at the purpose of the base construction.
The built up earth plinth may be primarily to raise the height of the furnace. This appears to be explained in commentary. Other than raising the furnace for ease of access, its hard to understand why.
Considerable care is taken with the construction of the base, with a layer of straw, covered with a clay cobb plate, this in turn with what appears to be a semi refractory layer. (Light coloured clay that appears to be mixed with charcoal fines.
This same light material is used as the inner layer for what looks like the first 10 cm of the furnace wall.

The interior diameter of the furnace looks to be roughly 20 - 25 cm.

Note the bellows size and style (medium size double action - Late Medieval) Depending on pump rate (hard to determine from the video) this equipment should be able to supply plenty of air volume.
Use of steel pipe for bellows tube / tuyere
Set at basically flat angle (only slight downwards)
Very shallow base distance below tuyere (perhaps 10 cm??)

The is use of round port for tapping. Appears to be at same height as the tuyere.
There was no tapping event recorded, and no tap slag visible in later parts of the smelt.

Total furnace height looks quite short, the entire furnace may achieve (barely) 40 cm total. Considering placement of the tuyere, this suggests a very short reactive column.

Charcoal is roughly broken for size, scoop from pile method for screening out fines.

Ore appears to be hematite / iron sand or oxide powder (brown ochre) ?
Laid in a large slabs rather than sprinkled through charges. Only two charges shown, and it would be important to know how much ore was used.

There is use of flux (a fine white powder - may be borax?) near end of smelt.
May be explained in commentary, but why?

Furnace is allowed to burn out and basically go cold.
Extraction is by breaking out rear wall to expose interior.

When the interior is exposed, the slag mass certainly looks considerably above the height of the tuyere. Was the smelt halted because the tuyere was blocked? (Commentary may explain?)

On the extraction, three pieces are pulled aside.
The first (which is the piece in the smelter's hand near the end) is holding heat in a manner that at least suggests there may be some iron in it. If so, it is extremely lacy and small. The second piece is dense and dark, and looks like iron rich slag. The last piece (seen again near the end of the video) is light coloured green, typical of an iron poor slag (melted furnace walls).
Obviously the comments of the team would be important to understanding their results.

It appears the smelt master has determined the pieces containing iron by look and weight. It might have been more instructive (for him and us) if these fragments had remained hot enough that they could have been hammer compressed



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

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