Friday, October 31, 2008

DARC Fall Smelt

Saturday November 8 - Wareham

Regular Readers - You would have all gotten some the background for the Icelandic smelt series that Neil Peterson, Kevin Smith and I have been undergoing of late in bits through earlier postings (search HALS) A nicely formated overview is now available on the Wareham Iron Smelting site.

Our last test smelt at Thanksgiving was just barely snatched back from disaster. Obviously we need more practice with the blow hole and bellows plate set up. It was clear that adding the lack of ability to access the tap arch space was a bit too much. I don't think the overall layout for the HALS set up is a problem of itself, other than the restriction that will be imposed by the location of the bellows.

(left) Bellows plate and blow hole with set back bellows tube - just at the point were the slag bowl started to freeze over and restrict air flow.

(right) Solution that saved the smelt - reverting to ceramic tube as insert tuyere.

(left) The lower rear wall after the smelt. Note the broken area and deep fractures to the upper left. The front (above the tuyere) was completely broken away.
The smelter shaft constructed for Thanksgiving is pretty much shot. At this point there is only about half of it remaining. So it will be just as easy to build a new shaft. (The weather is supposed to warm up here over the next couple of days.) I'd like to try to work with the horse manure for the entire furnace (more like Michael Nissen does). Whether I can gather enough dried manure (this late in the season) will be the bottle neck here.

I will forge up a tapered bellows pipe like the one Michael has described. Remember we had started to lean that way with the copper tuyere. Ken Cook and Gus Gissing have long been suggesting this approach

On ore, our stocks are starting to deplete. All the taconite got used up on the last smelt (athough I'm sure we can get more). There is some of the DARC dirt 1 remaining, but not enough for a smelt on its own. There is some of the poorer Virginia Rock roasted but in need of crushing. I have several hundred pounds of the hematite grit, and suggest mixing those two.
Altogether there is enough of the Williamsburg rock for one smelt. Maybe enough raw for three using the poor Viriginia mixed 50/50 with hematite. I will be picking up another bag of spanish red to mix to DARC dirt. There is also a pail full of gromps - but best these be used in a smelt in a standard furnace.

The last hole in supplies is charcoal. We currently have enough on hand for one full smelt and a bit (I think there are about 100 kg taken altogether, mainly as Black Diamond ) We have been more fuel efficient of late, mainly by going straight to full sized ore charges and reducing the length of burn down.

So in detail:

work inside the Hals layout
new 5 cm smelter shaft
bellows plate and blow pipe
switch to tapered tube (blower)
hang air pipe system to free tap arch
ore 50 / 50 poor Virginia / hematite (22 - 25 kg?)
(aim for Hals sized bloom - 15 x 15 x 10 / 5 kg)

Wednesday, October 22, 2008

Sunday, October 19, 2008

Medieval Cast Iron?

As a short answer to a question posted to the SCA Ontario discussion:

'Is cast iron cookware historically correct for the Medieval Period?'

First challenge - Define 'medieval'?
(The SCA officially runs from 'the fall of Rome to the English Civil War' = 450 - 1650 AD )

Second challenge - do you conform to materials and objects inside your personna time frame alone?

Third challenge - some fast metallurgy:
- The element iron will absorb carbon during its processing from iron oxides (ore) as it is reduced to actual metal.
- If you have no carbon, you get soft 'wrought' iron. This is easy to hot hammer, relatively soft but flexible. Ideal for hinges and handles.
- If you have small amounts of carbon, the metal becomes increasingly hard and brittle. By small I mean from .2 to up to about 1 % (not very much). Our modern mild steel has roughly .2 %. A machette or axe has roughly .5 %. A carving chisel or scaple has roughly 1 %.
- Over about 1.5 % the characteristics of the metal change, alowing you to liquify the metal without damaging it (actually 'burning' it back to iron oxide). This allows you to pour into sand molds for pots and pans. This is cast iron. The cost is that the metal is extremely brittle (drop and it shatters).

Now the time points (real fast!)

- For the period up to the Crusades (- 1200), NO cast iron
The direct bloomery furnaces used to turn iron ore into metal had little predictable control over carbon content. If high carbon liquid cast iron was produced, it was considered a waste product and returned into the furnace. No objects were made of this material in the West. (China is another story)

- In the central part of the Middle Ages proper (1200 to 1500) - RARE cast iron.
The creation of metallic iron from ore was a larger scale two part process. A higher carbon metal was created from ore, then the carbon selectively removed to the desired point in a second furnace / forge process. So cast iron was produced, but for objects was a curiosity rather than a normally employed material. You will find some small objects, mainly things like jewelery or small sculptural pieces (think fist sized). These are quite uncommon and tend into the Rennaissance .

- Post Medieval (1600 +) - LIMITED cast iron
True use of deliberate cast iron does not develop untill the introduction of coal as a smelting fuel in the very late 1500's on the continent and into the early 1600's in England. By the time of Jamestown Virginia (1610 +) there are starting to be small pots available. These were extremely expensive and limited to the upper class. Think of the 'witches caldron' shape with three legs, maybe holding one or two gallons.

- Settlement Era (1700 +) GENERAL use of cast iron
Cast iron becomes easier to produce and control. It still is expensive, but prices and availability have dropped to the point that many families can affort a SINGLE pot or pan.

- Industrial Age (1820 +) EXTENSIVE use of cast iron
Cast iron cookware will not become both cheap and widespread until the introduction of steam powered technologies. The Victorian period has the largest use of cast iron for all kinds of objects, from personal goods to architectureal.

Simple answer:

No cast iron cookware in a medieval setting. All pots and pans made of riveted iron or copper alloy (early period bronze, later period brass) sheet. Few pieces per household.

For a simple overview of pre-Conquest cookware
Norse Trade Goods - Cookwares

Saturday, October 18, 2008

...and now for something completely different

Tangerine Dream - Ricochet

Recorded in 1975, Live (I think at Coventry Cathedral)

My favorite of all their pieces - boy I wish I had been there! (and yes, I was listening to this when it was pretty much new)

Wednesday, October 15, 2008

Icelandic / Hals - VIDEO

For some reason I don't seem to get the 'embedded' code to work correctly. The direct link is :
Icelandic Iron Smelt

Work Test A - Icelandic / Hals smelter

This is just a fast overview of the results of the smelt here at Wareham on Sunday Oct 12.
Smeltmaster duties were shared by Neil Peterson and myself, with Ken Cook assisting.

As readers would have seen in earlier postings, the intent here was to lay out a working area based on the archaeology of a Viking Age 'industrial' iron smelting complex at Hals in Iceland. Details on the excavation have been provided by Kevin Smith. The working area was 2 x 2 metres, with the smelter inset into the centre and a slot cut back on one side to allow for access to the smelter wall. The initial set up included a bellows plate and a blow tube tuyere. We also placed a cut out to block in the most likely position of a suitable bellows, but in fact used an electric blower for air.
For this smelt, the remainder of our supply of commerical taconite was exended with a quanity of the poorer quality Virginia rock ore Vandy and I had gathered in 2007.

This set up worked fairly well for the first part of the smelt sequence. About 2 hours after the first addition of ore however, liquid slag from the top of the bowl started to crust over the lower half of of the hole in the bellows plate. An attempt was made to reduce the slag level by pulling out gathers of slag with a steel rod. Due to slow action, lack of experience (or maybe just picking the wrong solution), the air hole beame blocked and the interior temperature of the smelter began to crash. Through some frantic work, the tuyere was changed back to our usual insert type, and we were able to salvage the smelt and slowly increase the internal temperatures again. This modification marked the end of our intended experiment, but the smelt was able to continue to completion.

The initial plan was to use a top extraction. It proved extremely difficult to free the resulting bloom. So in the end, a bottom extraction through the tap arch was used, resulting in considerable damage to the smelter. One other effect was that the bloom was considerably colder than is usual upon removal from the smelter. This greatly reduced the amount of consolodation and shaping / cutting that could be undertaken. (The relative exhaustion of team members not withstanding!)

Although the full smelt could not be carried out using the intended bellows plate / blow tube combination, the end result was a good bloom. The yield is a bit lower than our usual.

Total bloom wieght - 4.9 kg
Total ore added - 23 kg
Yield - 18%
Total charcoal - 48 kg
Total Time - 6 hours (plus extraction)

Tuesday, October 14, 2008

VOTE for ARTS - who says what

Maybe too late to m
A summary forwarded to me just this morning, clearly listing what Party is intending what policies for the arts.


A useful site to see what is going down in your riding can be found on the '' web site. Although intended to rally the Eco Vote, it will give you the most recent polling numbers for your area.

Liberal Arts Platform
The Liberal Party has put out An Action Plan for the 21st Century, which lays out all their policies and positions. Section seven is devoted to Supporting Canadian Culture, and the introductory paragraph says that “Canada’s diverse arts and cultural community plays a vital role in our national identity. Cultural activity fosters vibrant, liveable cities and communities, and supports innovation, helps us understand our past and imagine our future, and stimulates our economy.”
The Liberals hi-light the following commitments in their platform:
 A Liberal government will reverse recent cuts to arts and cultural programs.
 We will increase the Canadian Film and Video Production Tax Credit to 30 percent.
 A Liberal government will double the annual funding to the Canada Council for the Arts.
 A Liberal government will provide income averaging for artists, an important tool for helping this country’s writers, artists and musicians continue to excel.
The Liberals have been promising to restore the cuts to Public Diplomacy Programs at DFAIT since the first cuts were made to that program in 2006, and their current promise to reverse the recent arts funding cuts includes funding that was eliminated from DFAIT as well. In addition, they commit to increasing funding for international arts promotion and the Museums Assistance Program, and the creation of a Canadian Digital Media Strategy.
You can find the entire Liberal Party Platform on their website

Conservative Arts Platform
There is no mention of arts or culture in the official Conservative Platform documents. However, the Conservative Party has made some recent announcement that may have positive outcomes for the arts sector:
1. The extension of maternity benefits to include independent contractors, which will enable some artists to take maternity leave.
2. The creation of a Tax Credit of up to $500 similar to the Child Fitness Tax Credit, which will include some arts activities for children under the age of 16. A committee will be convened to determine which arts activities are eligible.
3. The Conservative Party will not revive Bill C-10 in the session. Bill C-10, which was introduced by the Conservative Party is the last session, would have allowed the government to revoke tax credits given to films that government deemed to be contrary to the public interest.
Copies of the press releases with more information about the above can be found on their web site

Green Party Arts Platform
The Green Party has laid out their commitment to Arts and Culture in great detail. The document begins “While the major contributions made by Arts and Culture to Canada’s economy are clearly quantifiable and beneficial, the Green Party of Canada recognizes that the qualitative impact of Arts and Culture to Canadian Society is priceless.”
The document goes on to describe impact of the arts the economy, social well-being, employment, tourism, Canadian identity and youth.
The Green Party makes the following commitment:
1. Increase funding to all of Canada’s Arts and Culture organizations including The Canada Council for the Arts, Telefilm Canada, orchestras, theatres and publishers. The goal will be to make increases in this sector commensurate with increases in support over the years for other sectors of the economy such as transport, the auto industry, health care, and the oil and gas industry.
2. Provide stable base-funding for the CBC so it can continue to provide quality Canadian content television and radio programming in both official languages to all Canadians.
3. Ensure that the Canadian Radio-television and Telecommunications Commission (CRTC) reserves more bandwidth for independent and non-profit stations.
4. Enact legislation that requires cinemas and video chains to have at least 20 % Canadian content.
5. Restore and improve arm’s length principles in the governance of arts and cultural institutions and agencies under the federal jurisdiction. In keeping with such a position, we believe that the heads of Canada’s cultural organizations such as the CRTC, Canada Council, CBC and Telefilm Canada should not be appointed by the political party in power but by an arm’s length committee made up of competent people representative of the various diverse stakeholders in Canadian society.
6. Eliminate current legislation before the Senate that would give politically-appointed censors the right to deprive films of the right to a tax credit if their content is deemed “unfit.” In such a context films by some of Canada’s most internationally celebrated film-makers-- including Egoyan, Cronenburg, and Arcand--would likely never have been made.
7. Increase support for community arts programs and facilities across Canada by establishing stable base-funding at a set percentage of the federal budget.
8. Equalize federal funding for Arts and Culture among provinces, territories and municipalities to make it consistent with the provinces and municipalities that have the highest current standards.
9. Provide incentives to all provinces and territories to restore and improve Arts and Culture components to schools and extra-curricular activities not only in urban but also in rural areas.
10. Extend income tax relief and incentives to artists (on the very successful models established by Ireland and the city of Berlin). Doing so will:
• encourage artists to settle in Canada and build businesses here
• result in other (usually) white collar “clean” industries that follow the arts jobs and dollars
• help to provide meaningful jobs to university and college graduates
• enrich schools and their offerings thereby attracting immigrants to settle in rural areas
• revitalize and discover talent in communities where traditional industries are declining and young people are leaving
11. Follow and implement recommendations of Canadian Conference of the Arts in order to enable artists to access various social programs including Employment Insurance, Worker’s Compensation and Canada Pension Plan.
12. Change the Canada Revenue Act to allow arts and culture workers to benefit from a tax averaging plan that will take into account the fact that lean years often precede and follow the good year when a show is produced, a book is published and a grant or a prize is won.
13. Protect Canada’s cultural identity during trade negotiations.
14. Restore the government provided transport service (eliminated by the
Harper government) to allow the transport of exhibitions between museums and galleries;
15. Protect the copyright for artists such that they are not surrendered to museums and galleries in the process of permitting exhibits.
The complete Arts and Culture policy of the Green Party can be found at their web site

NDP Arts Platform
The NDP has not made a commitment to Arts and Culture in their policy documents. However, Jack Layton has made commitments on behalf of his party at various events, and in a press release issued from his office on September 23, 2008.
The NDP has promised to:
 Introduce income-averaging for artists, modeled directly on the long-standing practice in the province of Quebec.
 Provide an annual federal tax exemption of $20,000 for income earned from copyright and residuals income.
 Reform the CRTC to ensure that prime television in French and English is written, directed, starts, and it about Canada and Canadians.
 Prove Radio-Canada and CBC with stable, secure and adequate funding.
 Protect and properly fund Telefilm and the Canadian Television Fund.
 Protect and properly fund the Canada Council.
 Reverse Mr. Harper’s $45 million cutback to culture.
The press release is posted on the at the
NDP web site

And just out of interest …..

Bloc Québécois Arts Platform
The Bloc Québécois have released their Party Platform. As usually the majority of arts and culture initiatives proposed by the Bloc pertain only to Quebec. But some, such as the proposed increase to the budget of the Canada Council for the Arts, have potential benefits for the national arts sector.
 Will submit once again its law/bill project on the recognition of a national québécois cinema.
 Will ask for the transfer of all responsibilities in the field of culture. Till then, it will keep defending the cultural sector against all attacks by the federal government and it will exhort the federal government not to abolish the cultural programmes, wildly cut down by the Conservatives.
 Intends to submit a proposal to allow income-averaging over a five year period.
 Will keep asking the government to create a framework for the extension of employment insurance benefits to independent contractors, many of which are artists and culture workers.
 Will increase the Canada Council for the Arts budget until it reaches an annual envelope of $300 million.
 Has been asking since 2007 the creation of a $30 million programme to support festivals. It has also been asking that the sums allocated to Quebec be transferred to the québécois government.
 Will increase by $50 million the Telefilm budget, including $20 million for the québécois cinema.
 Is seeking the creation of a documentary film and IMAX film fund, and that sums allocated to québécois cinema reflect the cultural consumption of québécois habits.
 Will abolish the federal sales tax on books.
 Will make sure that the new Copyright Law will be equitable and will not disadvantage either the creators or the consumers.
 Will ask the federal government to present a new museum policy that incorporates the current needs of québécois and Canadians museums.
 Proposes the implementation of incentives favouring the distribution and recognition of cultural regional works as well as the emergence of new talents. The Bloc Québécois believes that these measures will guarantee access to regional artists to a minimum of 10% of the media space dedicated to culture.
The Bloc Québécois party platform can be found (in French only) on their web site

Wednesday, October 08, 2008

Bloom to Object - 'Layered Test Seax'

Now I should say that at this point, individual blooms are still a lot like children (you hate to see them change and leave home). I have compacted a few pieces or smaller blooms to bars, had not made the step from bar to object. In so much I was one of the featured demonstrators f Quad State 08, I though I really should have some work forged up from my own blooms for display in the gallery.

The first piece I made up was 'Offering Bowl', which I earlier in the month.

The second piece was actually intended more as a test of an idea, extended into a finished object. The concept was this: 'Would a slab of bloom iron, folded and twisted in the pattern weld technique, actually show any distinctive patterning?'

The parent bloom used for both 'Offering Bowl' and the resulting 'Layer Test Seax' was one made at Early Iron 2 (Cooperstown 2005), the 'Reserection' bloom. The bloom bears its name from the unusual process that created it. I had been supervising Elizabeth Hendrics and Toby Bashaw (a team from MIT). Unfortuneately, Elizabeth had not been feeling well and they had to abandon their efforts 3/4 the way through the smelt sequence. I thought it a shame to just abandon the process, so took over with a modified method for the last roughly 2 hours of the smelt. When the smelter was opened up, there were clearly two distinctive bloom masses. Below was a rather lacy and wide mass, and sitting on top a quite separate small puck shaped one.The gap were the switch over had taken place had clearly dropped the temperature for just long enough that the final work I had done with the furnace had created this second separate bloom. This proved to be a very workable low carbon iron.

As with Offering Bowl, the work on Layer Test Seax had started with two fragments from an earlier (failed) attempt to forge a larger vessel. My best guess is that the compacted bloom had undergone two fold in half and weld sequences at that point.
Two pieces, each roughly 1/4 inch thick and about 2 x 3 inches, were tack welded (with MIG) to a mild steel bar to allow them to be worked on. These were then surface welded with a hand hammer. A second welding heat was taken, and the block worked under the air hammer. The material was drawn out enough to allow it to be cut and stacked in two, then the weld sequence repeated. This step was repeated twice, each time rotating the line of the fold by 90 degrees.
At that point, the billet was drawn to a longer bar, then loosely twisted, cut in half and welded again. If you count just the folds and welds from the starting pieces, that gave 16 layers total.
This last billet was forged out to a single piece knife, the shape loosely based on Romano British table knives and using the distinctive seax blade shape from the Dark Ages. The blade tapers in thickness from hilt towards point. It also was shaped with a strong V cross section. (Both common features on Viking Age knives.) The total length is 9 inches, with 5 inches of blade. It is 1" wide and 3/16" thick at the back at its widest point (just at the transition to the hilt).
The blade was quenched in water from bright orange, but not tempered. After final polishing (to 120 grit) it was etched in Ferric Chloride. Note that as a test and display piece, the cutting edge was intentionally not finished to sharpness.

These images roughly life sized - direct scans of the knife.
(The some of the gold discolouration is due to a slight amount of copper plating out of the etchant - most is due to some effect of the scanning process.)

Looking at a close up, you can clearly see variations in colour that are at root caused by variations in carbon content of metal. The source bloomery iron will of course have stringer inclusions of microscopic slag, which does account for some of these lines (the brighter coloured ones?). Also the process of working the metal repeatedly at a welding heat will also allow a certain amount of carbon migration into the surfaces of the plates. With at least four weld sequences, each containing two uses of welding temperatures, there would have been certainly some infusion of carbon along the surfaces. The combination of carbon modification and slag inclusions is what is creating the subtle patterning.
One question was the location of two small bright shine patches just at either end of the finished knife. My best guess is that these mark some material from the filler wire on the MIG weld to the handle bar. This bar was cut away before the finished layered billet was forged to the finished shape, but it appears some of the quite different metal alloy was incorporated into the blade.

A number of decorative possibilities suggest themselves from this test piece. One thing that has surprised me is that the blade surface shows the distinctive finger print discolourations from being handled while on display. I would have thought a soft iron relatively immune from this problem. Again this points to a slightly higher carbon content to the metal than I first expected.

Tuesday, October 07, 2008

Thanksgiving / Hals setup

Taken with the earlier discussion on the possible layout of the Icelandic smelter at Hals:
This is was the situation at the smelter work area at the beginning of the week. You can see that our last (June 08) clay cobb smelter remains in excellent condition. By intent, I had set up the area with our working smelter to the right side. This was so that a second smelter could be installed to the left hand side of the block retaining wall.

Next is a simple plan view of the existing situation with some of the significant measurements, with a theoretical layout of the Icelandic smelter indicated. I have taken two of the available rail road ties and used these to block in the 2 m x 2m size. On the actual above ground sod construction, this would be a log crib. With the length of the ties actually a bit more than required (and lots of stones!) I set the rear dimension using a row of rocks. By removing three stacks of the retaining wall blocks, I end up with about the correct opening for the front V of a working area leading back to the smelter front wall. Measuring from the current work surface to the tops of the two rail ties, you end up with about the correct height proposed for the Icelandic construction.

the next drawing is an plan view of my proposed set up for the Thanksgiving smelt as it overlays the existing area. As outlined in the last posting, Work Dynamic is the primary thing being explored in this experiment. The position of the hand powered bellows is indicated, and will be blocked in with a plywood cut out for this smelt. The space between the V of the concrete block walls is the length of a standard brick (about 25 cm).

After much grunting and groaning (about 6 hours worth).
You can see in the photograph that I have cut back the bank to create the V shape work area. The concrete blocks have been used to secure the walls. I suspect that in the historic smelter, these could be a combination of wood (towards the front) and stone slab (at the smelter surface). Our own past experience has shown that any wood within about 40 cm or so from the smelter wall will certainly catch on fire from the radiant heat. At this point I had to scrounge a few more blocks for the left side, so the top surface has not been copletely packed or leveled. As usual for Wareham, the larger rocks (about head size) seen on the left were of course just sticking out an inch or so from my digging lines! As of today (Tuesday 7 AM) I have not actually cut down the cylindrical hole for the smelter itself, which is marked by the plastic pail.

The next illustration is a section through the centre of the smelter roughly S-N. Our standard Norse Short Shaft smelter construction will be used. You can see that it comfortably fits into the earth banking, with its top about flush with the upper work area. One overall question that remains is how to construct the area of the smelter that will be exposed to open air (tap arch, tuyere and the 'heat zone'). Given the relative scarcity of clay in Iceland, I suggest that the historic smelters would have used stone slab with an inset clay bellows plate construction.

The last drawing is a section (cut E-W) I have laid out the working position of the current smelter bellows. Oour tested angle of 23 down for the tuyere is extended along the length of the bellows (about 100 cm) plus the length of our normal ceramic tuyere tube (30 cm). This is shown with the tuyere inserted at 5 cm proud of the smelter interior wall. If the blow tube method is undertaken, the whole workings of the bellows and tuyere would be moved back about 10 cm away from the front edge of the smelter wall. Michael Nissen normally uses a less pronounced angle on his smelter set ups, so the combination should retain a correct working height for a potential bellows operator.

Sunday, October 05, 2008

Thanksgiving at Hals in Wareham (1)

This is a fairly long posting, expanded from a recent set of e-mails.

There has been some discussion (Kevin Smith / Ken Cook / Neil Peterson and myself) of the framework for the Thanksgiving smelt. For those keenly interested, this will be at Wareham Sunday October 12.

As regular readers may remember, the DARC smelt team is working towards a full reconstruction based on the evidence from the Hals site in Iceland. The excavation work is being done by Kevin Smith (reference : 'Ore Fire, Hammer Sickle : Iron Production in Viking Age and Early Medieval Iceland') An earlier discussion - 'Towards an Icelandic Smelter'.
Possible layout for the furnaces at Hals based on remains.

There are a number of individual elements that go towards the full reconstruction:

Sod cone in a log frame construction
Hand powered bellows
Use of thin clay / marl liner on interior
Working down a narrow slot
Tuere above tap arch set up
Stone slab front construction (?)
Use of 'bellows plate' (?)
Use of primary bog ore material

The sod construction represents a major logistics challenge at this point. We need a skid of grass sod (hopefully donated). Time is too tight to set this up for this Thanksgiving. I also think there are a number of other pieces to work up before we go that full construction. We can certainly use an earth banked design which will allow us to test a number of the other elements.

Hand powered bellows is almost a party trick at this point. A full test is more about labour organization than air delivery effect on the smelt. We should get some solid delivery numbers on the new test bellows. This can be done as a simple working test as was done last June, using multiple operators and an averaging aneomometer. Frankly, I'm sure that new bellows unit will give us the required volumes, so this is largely a work dynamic more than technical issue. (see earlier posts)

Use of the thin liner should represent a major test on its own. The simple way (see below) would be to dig a cylinder into our pond earth bank for the smelter, then line the dirt with the thin clay. We will have to substitute straight ball clay for marl - as we just can't GET any marl / 'glacial blue clay). I did read in Pleiner (someplace?) about furnaces that were simple cylinderical holes cut into the ground near the edge of a natural bank. Then lined with a thin) layer of clay as fire proofing. (I think these were English / Anglo Saxon??) The evidence from Hals does not appear to give us either the thickness, or mixture of this suspected clay liner. Kevin Smith has suggested 2 - 5 cm. I suspect you would want to use the horse manure cobb here.

The work dynamic of the Icelandic is the easiest thing to work on right now. Ken and I talked it over, and we think we can 'fake' this out by digging a key hole into the side of the pond bank (more details below). This would let us use the upper ground level as if it was the top of the sod construction., blocking out the 2 metre square working platform. Now this would require us to undertake all the physical adjustments to the smelt bowl working down a roughly 1 m long slot. I think we should also fake the position of a man powered bellows by placing a plywood cut out, but at this point still use the blower air system. This should definitely be one of those 'rake the sand' experiments to look at work and debris patterns.

The major shift for us is the placement of the tuyere directly above a small tap arch. Michael Nissen from Ribe uses that rough layout all the time on his smelters. I'm not really expecting any big problem here. (see above)

Now, we did mess with the stone slab construction for the Thanksgiving and Fall smelts of 2007. The first of these we did try to use the 'blow tube' style tuyere (tuyere set back from blast hole), but with poor results. The use of a stone front on the smelter (or entire stone construction) has been tested to success. My own interpretation of the layout from Hals leads me to believe you would want to(ideally) construct the smelter with a stone slab set above a clay bellows plate. Our own tests certainly suggest that any stone used in this fashion will bear significant and distinctive patterns. Kevin Smith has reported "We do have a small number of spalls with slag that could make sense from a similar use.", from a discussion on our results from the October 2007 smelts.

What about the use of a separate clay bellows plate? This represents both an archaeological question at its core. Again, there appears to be no specific artifact evidence, but this is balanced against the relatively fragile nature of these plates. Does the evidence indicate STONE used as the front section of the smelter around the tuyere? . What about the use of a separate clay cobb 'plate'? A number of smelts (mainly Nissen) have shown that a roughly 15 x 20 cm by 2 cm thick plate of dry horse manure mixed with clay works extremely well.

The third piece of this method is the set up with the tuyere actually sitting proud of the smelter wall. I did use the combination of bellows plate (thin plate around tuyere entry) with blow tube set up at Smeltfest 08 for two smelts with good results. Also watched this done three times in Denmark. So taken together, I'm pretty sure we can get this to work.

We do need to tweak the mix on the DARC Dirt. Due to bad communications (and poorer math!) the actual iron content of the first round of test materials was really on the low end. It did match the St Lunaire samples, but ideally I'd rather bump up the iron content to something richer and more likely to give higher end yields.
Given time and supplies, it might make more sense to use a richer ore body for this next experiment. We also should try to match the ore content from Hals if at all possible.


Trying to keep with the wisdom of not changing 5 things at once (!!) I propose the following for the Thanksgiving smelt:

1) Overall set up is a totally earth surrounded smelter at the end of a slot - with the layout similar to those at Hals (see below)
2) Use a thick walled clay cobb furnace structure.
3) Set up the work area with a fresh sand base.
4) Use a known pure ore (the taconite likely)
5) Fake out the location of the hand bellows, but use the electric blower for air

A) Use either stone slab or bellows plate construction
B) Use blow tube arrangement for the tuyere (which can quickly be modified to our normal insert tuyere if required.

This suggests to me one minor (number 1) plus two major changes (A / B). I have worked both A / B, and 1 is more a modified work dynamic than an actual major change.

The set up of the furnace with only a small tap arch down a slot certainly leads to a top extraction. To that end we should aim for a 3 - 5 kg bloom.

(More on Construction in the next Post)

Friday, October 03, 2008

VOTE for the ARTS

My wife Vandy follows the blog of Stephanie Pearl-McPhee regularly. The lady has quite a whit and I find some of her commentaries extremely funny - and to the point.
'Dear Mr. Harper' is a recent open letter to our current PM.
Last night was the English Language debate. Yes, Mr Harper, we certainly must spend more on bricks and mortor. Museums, especially living history museums, are falling appart through simple neglect. Since when were these 'frills? If Canadians are to remain Canadian, we HAVE to remind everyone that we do in fact have a history different from George Bush's Fortress America.
But the soul of Canada is partially expressed via its artists. Make us all starve to death, or conform to your personal vision of morality, and you kill our Canadian collective soul. (A income tax credit? You were JOKING - right? None of the full time working artists I know make enough to even pay any income tax!)
New working plan! Instead of so much of your 'arts funding' being consumed by mere bureaucrats, do this instead:
- Take all the money you distain to provide for the arts.
- Have all the working artists interested submit their names.
- Divide money by number of artists.
- Mail out cheques, the same amount to each of us.
Yes some working artists might blow the money on things like a new roof or food.

The end result would be a huge increase in actual WORK produced
Who knows, YOU might even like some of it...

Grave Goods - Pictorial Overview

Catherine Crowe, fellow member of An Droichead, has made up a very good looking quick overview of the artists particpating in Grave Goods. The detail thumbnails give you a feel for the range of techniques and the excellent quality of the individual artists and some of their work.
Grave Goods on the Bridge

The show continues at the Woodstock Museum until Saturday November 1, 2008

We are planning to close the exhibit with a 'Black and White Masque' that evening. Plan to attend! (details to come)

Thursday, October 02, 2008

Iron Smelt Demo on ANVILFIRE IS a unique resource for blacksmiths and related metal workers. Anvilfire is your best on-line metalworking information source.
Anvilfire is dedicated to advancing modern blacksmithing while retaining traditional standards of craftsmanship.

Jock Dempsey
, the honcho behind the excellent Anvilfire web site, attended a good chunk of the Quad State smelting demo. He wrote up a very good overview article of what he saw, including a great set of clear photographs of the entire extraction process. Please take a look
The only small quibble I have with the report is that the ore used I actually did personally dig out of a sand bank at Williamsburg Virginia. Part of the Friday 'smelter prep' part of the demonstration was roasting and crushing that ore.

Thanks for a great report Jock!

Wednesday, October 01, 2008

Iron Smelt Demo at Quad State

If the clip does not load - go straight to YouTube HERE

That is a short form overview of the demonstration smet I undertook at the Southern Ohio Forge & Anvil's Quad State event over September 27 & 28. I was assisted by Ken Cook (of DARC) and David Robertson (who shot the raw video). The basic facts:
- furnace type : Norse Short Shaft
- overall duration : about 7 plus hours (about 9 hours total)
- ore added : 65 lb / 30 kg
- charcoal used : about 150 lb / 65 kg
- bloom produced : 21 lb / 10 kg
- yield : roughly 30 %

The finished bloom was cut to four pieces which were sold in the fund raising auction. The metal spark tested out with just a slight amount of carbon (about like a 1005 rivet material).

Thanks for Ken for minding the smelter while I talked (for hours and hours!)

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

COPYRIGHT NOTICE - All posted text and images @ Darrell Markewitz.
No duplication, in whole or in part, is permitted without the author's expressed written permission.
For a detailed copyright statement : go HERE