Adaptable Furnace Base

This piece of equipment a long time coming!

The concept started with my experience at the Scottish Sculpture Workshop in 2017. Unlike previous work there (on the Turf to Tools project) the 2017 visit was intended purely as a personal artist's retreat. A good chunk of the one week was spent with Beth Bidwell in the ceramics studio. I returned to a lost love (wheel thrown pottery) and took part in several kiln firings. This included raku, using a propane fired furnace.

This was a fixed propane fired furnace base, with a moveable top section.
SSW uses a number of high BTU output propane burners, which they can switch out to provide heat for a number of different furnace / heating applications. (Wax burn out, bronze and iron casting, ceramics, special projects.)
Here you see the furnaace base, which is made up from a cut truck wheel rim, lined with castable refractory material. A simple hole in the side directs the blast from the propane burner. This runs on a ventri effect (no electric blower required). Although this base is quite heavy, it is mounted to a wheeled cart to allow it to be shifted around the concrete paved SSW central courtyard.
SSW alumni George Beasley had created the upper kiln segment seen here.
A frame and counterweighted pulley system is attached to a section cut from a metal 45 gallon drum. This containment was lined with k-wool insulation, and had a couple of viewing ports and top exhaust vents cut into it.  The counterweight system allowed the upper to be shifted upwards and easily blocked into place as this was done.
In use, the upper area was set with kiln shelves and supports, containing the previously bisque fired ceramic pieces to be placed. A bit of care needs to be taken at the initial ignition of the propane burner - too much heat, too quickly, will simply shatter the pottery. Over time, the propane feed is increased, eventually bringing the entire upper stack to correct high temperature. The required point is judged by using 'cones' - the heat effect on these observed through a viewing port. *

I was impressed on how basically simple this whole design was.

For a good long while now, I had wanted to set up a larger equipment for bronze casting at the Wareham Forge. I have done a fair amount of small scale metal casting, with lost wax investment (silver and gold), using tin alloy (pewter) in stone, and using the 'green sand' method for bronze. I have been limited in the size of bronze objects by the heat source - with a oxy propane torch. This allows me to effectively head only a small crucible, roughly the volume of a walnut.

Original lead artifact (c 800?) / interpretation in pewter / duplicate in bronze

My intent was to build a furnace that would be able to heat about a litre volume of bronze. At least to start I would continue with the green sand mould making, but this would allow me to cast small sculptures, sword or knife hilts, things like door hardware or boat fittings.

I had originally figured just to build the burner assemblies from pipe fittings, much as I had constructed a number of propane gas forges in use at the workshop here.

Over the winter, Princess Auto had these simple propane burners on sale. (For half price @ $25 each - the included, CSA certified, 10 foot hose normally runs about that much!) I bought three. These burners are rated at 500,000 BTU each.
In January, our 30 year old electric water heater (finally) failed. Although replacing it proved a real pain, it did leave me with the steel tank.
Add some scrounged fire brick I've long had on hand.
For ease of use, apply a heavy utility wagon wheel assembly (also from Princess Auto, purchased a good while back for just this kind of use).

Finished furnace base unit

I had cut (using a zip disk) the bottom roughly 1/3 away from the full tank.
That left me with a short cylinder, having a slightly domed base, all made of 1/8 inch thick steel. The interior is glass coated (think the enamel finish on an older stove), but that will not figure into the construction.
Outside Diameter = 24 inches
Height = 18 inches

Next step was measuring equal thirds around the circle, then cutting three suitable sized holes through the steel for eventual mounting of the three burners. I used the oxy-propane torch for this. ( I freely admit that cutting is something I never have done enough of to really get that good at!). I ended up using a worn down disk on my angle grinder to even out and correctly size each hole.

view down the completed interior

I have a set of half circular pottery kiln shelves, each of high temperature refractory plate, about 5/8 inch thick. One of these I cut to fit as fully as possible over the inside base of the steel shell. In the image above, you can see the edge of the part starting part circle, with the two smaller pieces I shaped to fit into the remaining base. This gives me a durable, hard, flat, fire proof floor. To fill the gaps around the slightly domed steel base, I used a refractory type material I mixed up. I had been saving damaged low density fire bricks, which I broke down to about the consistency of course sand. I mixed this 50 / 50 with powdered potter's clay, with water into a paste. (This using 'Hawthorn Fire Clay' - a fairly high melt point type I use here for building clay cobb iron smelting furnaces.)
As it turned out, the spacing proved almost perfect for the medium density fire bricks I had on hand. Each burner would be centred on one brick, with two bricks spacing around between each burner point. Once the fill and floor plate was installed, the remaining wall height came to the 9 inch length of the bricks (Ok - I did measure this out initially and cut to provide for this.) The resulting interior diameter is 12 inches.
I dry fit all the bricks, to transfer the location for the holes from those cut in the shell. As it turned out (luckily) the holes required were exactly the same size as the largest diameter in my hole cutting saw set. Short work with the hole saw mounted in a drill (cut from both sides to get through the thickness). Given the relatively fragile nature of the fire bricks, this proved a much easier task than I had suspected.
Again test for fit. Each of the bricks was mounted, again using the clay/brick dust mix as filler in the triangular gaps. It is expected this mix will contract a bit (10 %?) as it dries, but given the tight fit of the bricks I don't expect this will present any special durability problem in use.

close up of the master valve and fittings

Figuring out just how to link all the burners together proved a bit of a pain. The tubing diameter for all the pieces on the burners as purchased proved to be 1/4 inch. Maybe a 'standard' size - but not a size that any of my local stores had in supply. Once again, McDonald's Home Hardware in Dundalk saved me. They had just enough fittings, once a set of 1/4 to 1/2 inch couplings were found. This allowed me to get just enough of the (slightly more available?) 1/2 inch steel pipe fittings **
With use of a short piece of 1/4 thread fitted hose I had on hand, I managed to link all three burners together, via one central shut off valve. I further protected the short gas hose by covering it with the plastic pipe seen above.
I kept two of the burners with the original knob equipped flow valves. The central burner (seen above) is 'always on' - controlled by the main shut off. In use, you ignite that first burner from the main valve, then can control each of the remaining two burners individually. This combination should give the greatest flexibility and control over the propane flame = temperature.

The ideal would have been to mount the burners at a slight angle, both off centre along the side of the circular containment and also pointed down slightly towards the floor. This combined angle would server to create a circular vortex inside the furnace chamber, actually improving the flow of heat within. As it turned out, the distance from the brick interior through to the outside of of the shell, with burner mounted, can be seen to be almost exactly the distance to the air input slots already designed into the burner. By maintaining this, there should be the ideal amount of input air to feed the burner as it was original designed.

The completed furnace base unit weighs about 60 lbs. The combination of weight and size, plus the need to be able to store it when not in use in a working shop, lead me to use one of the utility wagon bases I had also purchased at Princess Auto some good while back (again on sale). I welded up a support from angle, which bolts on to the wagon base. The large 8 inch diameter wheels, which pivot on the front, make for good handling over the dirt floor of my workshop. As mounted, the completed unit stands 24 inches tall - a good height for manipulating the eventual crucibles. 


The last step is to take another of the kiln shelves and pattern and cut a suitable lid for this configuration of the furnace base. Ideally there should be a central hole cut, to allow burned gasses to escape. This will also allow two other functions when melting bronze :
1) Allow direct observation into the interior of the crucible (judge melting point)
2) Allow addition of more bronze material during a melt.
Will also need to figure some simple handle mounting to allow this lid to be quickly removed to extract heated crucibles.

Right now I have just used one of the supply hose assemblies that came with each burner. This pulls pressure straight out of the propane tank. There are two possible problems with this :
1) I have 40 lb propane tanks here as my normal supply for the gas forges. I have no clear idea how much fuel this x 3 burner system will draw, or how fast. The larger burners at SSW seemed to function a long time, but that was pulling from a 100 lb cylinder - one per burner. Testing required!
2) As designed, the burner is pulling straight off tank pressure. This is sure to drop (significantly) over the course of a longer session of heating.
I may introduce one of the variable 0 - 30 step down regulators into the system. This itself may need some testing to determine how this effects the overall operation. (??)
Right now I want to give the clay mix a couple of days to completely dry before the initial firing. (Potential steam explosion - and to reduce cracking effects).

COSTS :

Steel Shell = recycled
Firebrick = recycled (but about $10 per brick = $90)
clay = 1/2 bag = $12
floor plate = on hand (but about $55 each = $110)
burners  = on sale (1/2 price) at $25 each = $75
fittings = various = total $55
wagon base = on sale (1/2 price at $60)
TOTAL AS COMPLETED = $400


To start, I will be making casting crucibles of that same clay / brick dust mixture. I have had good results in the past using the same kind of clay / sand / horse manure mix used for the smelting furnaces. I may end up investing in a couple of modern high temperature refractory crucibles as well.

Next overall part of the project will be converting the upper portion of the water tank pieces into a containment to allow this furnace base to be used as a ceramic kiln as well...


* Use of 'cones' is a 'traditional' method of determining pottery kiln interior temperatures, still widely used in the absence of (often expensive) electric / electronic instruments.
A set of small, thin, pyramid shapes are made of clays with differing melting points. These then are set in a line, lowest slumping cone to the view port, increasing in heat effect towards the interior. Watching each cone slump in turn gives the potter a fairly accurate read on the furnace temperature.

** As it turned out I bought ALL the 1/8 and 1/2 fittings Brent had on hand. Well, Tuesday is order day for the normal Thursday delivery of re-stock. Sorry to anyone in Dundalk who got caught short. (But honestly, commonly I'm 'the only one that buys that stuff'...)

‘I was a Punk - Before YOU were a Punk’ *

On Co-Opting Symbols

Note to Readers:
This is proving a very difficult piece to write.
I am fully expecting a lot of kick back - but I would ask you read the whole piece - first. Comments will be welcome, but expect limits to ‘free speech’ will be applied. 

Thor's Hammer pendant from a Viking grave from Bredsatra, Sweden. At the Museum of National Antiquities' collection in Sweden, 10th century  (from a Pintrest collection)

What do you do, when objects you long have owned, suddenly are grabbed by some specific group, and incorporated into their personal vision?
Suddenly lifted completely out of context.
Look to the left hand in the image below:

Demonstrators carry Confederate and Nazi flags during the "Unite the Right" rally at Emancipation Park in Charlottesville, Virginia, on August 12, 2017. (Emily Molli/Sipa USA | AP Photo)

Or you realise that there may be new meanings applied to an old symbol, which you may have first chosen in innocence.
But then was co-oped by others, and distorted into something entirely different. This new association most certainly something you can not agree with!

Now, there are two quite different things going on here.
If you display an SS badge, or a Swastika flag, it is pretty damn certain what you are intending.
Seriously, you can rant all you want about ‘freedom of speech’, but everyone knows the pit of hate behind those symbols in the Modern Age. And exactly what you are clearly stating and promoting.

Modern Era and current Neo-Nazis, starting in Europe, had / have adopted many icons from ancient Goths and Norse. This all in a attempt to create a (false) ‘lineage’ to their views. The fascination of Hitler and his gang with the occult most certainly is another reason. There is most certainly a direct connection being made by current Neo-Nazis, both in Europe and as today active in the USA, with ‘Heathen’ / ‘Odin-ist’ practises and symbols. **

But to be absolutely clear, the historic artifacts had absolutely no connection what so ever with these purely modern, propaganda, uses of the imagery.
There was absolutely no concept of ‘White Power’ during the Viking Age.
Period.
(Show me some Archaeology. Not some written fantasy from the 1930's!)

Context can become everything.
I have a bronze ‘interpretation’ of the Bredsatra hammer. I was given it as a gift, back in the mid 1980's. Purchased by a friend who got it at the Coppergate Viking Centre in York, England.
When worn with obviously all Viking Age clothing, inside a living history demonstration, this is fully intended to represent an individual who was following the primary religion of that time, place and Cultural set. This is a historically based character, created for purely educational purposes.

If I should chose to wear that same token with street clothes, it may - or may not, symbolize my own personal faith view.
It may be most safe to say that if the token is worn under my shirt, next to my skin, it is most likely to actually be a religious symbol. Consider a Cross, Star of David, Pentacle, …

'Thor's Hammer' necklace, 1993. Pendant based on Rømersdal, Denmark

Worn over clothing, highly visible?

Seriously - it may just be ‘a nice bit of jewelry’.
But this may also be fully intended as a visual signature of membership in a ‘club’.
Wearing a Celtic ringed Cross? Likely you are showing both Christian and Irish associations.
Wearing a Thor’s Hammer? May certainly mean you are following some version of North European Paganism.

The same symbol printed on a T shirt?
Again, the most typical is ‘that is a cool design’.
It may only represent ‘I’m interested in that Cultural set’.

But horribly - increasingly, with the (repeated) rise of the extreme Right, White Supremacist and Neo-Nazis?
The ‘Thor’s Hammer’ is becoming yet another ‘code’ symbol for those groups.
Maybe like shaving your head?
Or sporting an SS Lightning or Swastika tattoo.

This becomes a form of Cultural Appropriation.
A very, very destructive kind.


While I was researching this piece - another symbol association struck me:

Neo Nazi demonstration in Myslenice Poland.
Contributor: Bart Pro / Alamy Stock Photo

Now, I have been working with Celtic inspired designs for some 45 years. This working primarily from artifact source materials. The objects made in Ireland, in the period of the Norse expansion (c 800 - 1000) show an wonderful blend of Celtic and Norse, pagan and Christian. I love the sweeping reversal curves from earlier La Tene objects. I have never been especially interested in Irish Catholicism, or it’s symbol meanings, however. The only time I have specifically used the Irish style 'high circle cross' in my work was in the creation of a forged steel grave marker.***

Taken from Avia Venefica : Celtic Cross Meaning

It should be remembered that the ancient carved stone cross seen above is not the typical. I have seen a number of these artifacts personally (Ireland and Scotland, museums in North America). The most common layout for the Celtic / Irish cross is a with a very long lower shaft, then three much shorter upper arms.

If you did an open internet image search using ‘celtic circle cross’ - this is what you would see :

Check on the reference link for image # 2.
The association of this symbol (also called ‘Odin’s Cross’ ??) with Neo Nazi’s is listed.

Reference link on image #7 ?

“ Legal disclaimer
This image shows (or resembles) a symbol that was used by the National Socialist (NSDAP/Nazi) government of Germany or an organization closely associated to it, or another party which has been banned by the Federal Constitutional Court of Germany. The use of insignia of organizations that have been banned in Germany (like the Nazi swastika or the arrow cross) are also illegal in Austria, Hungary, Poland, Czech Republic, France, Brazil, Israel, Ukraine, Russia and other countries, depending on context. In Germany, the applicable law is paragraph 86a of the criminal code (StGB), in Poland – Art. 256 of the criminal code (Dz.U. 1997 nr 88 poz. 553).”

How careful must we be, that the brush, now covered in black and blood, may now end up painting us as well?

 
Note : In preparing this piece, I have lifted a number of images off the open internet.

* Title taken from : the Tubes, 1977, song of the same name

** Before readers get offended!
I am NOT implying that any specific religious practice always implies a specific political viewpoint. If anything, the merging of Nazism with Odinist should be even more offensive to any who reject those political concepts.

*** Long installed in a small cemetery near Belleville, Ontario. Unfortunately, I have never seen the work as installed - or even have a reference photo of the finished piece. It stood about 5 feet tall. 

Antique? Vintage? Modern? (a Helmet)

On 2019-08-24 10:04 PM, 'M.D.' wrote:

I have a question about a helmet I was given some years ago, which I'm now hoping to sell.

The person who gave it to me first thought it was a costume replica, and now believes it to be a WW1 tank helmet. It was found in an antique shop.

It looks a lot like a medieval helmet and is very heavy. The back has a flexible "lobster tail" neck protector and the visor lifts somewhat.

An online search reveals nothing similar. Many helmets are more elegant; might this be a helmet a grunt soldier might have worn?

There are no tank helmets online that look anything like it.

Ok - so here is what I remembered, what I found, and what I think.

On tankers helmets:
I had a small drawing in a reference book
described as 're-inforced leather helmet'

image from : Weapons and Warfare of the 20th Century - Morris, Johnson, Chant & Willmott

With a slightly better idea what I was looking for, I was able to plug into Google images search on the internet and come up with a description at the Imperial War Museum in England (link):

image copied from the Imperial War Museum

So at least for British tank crews, your object remains quite different, as you had indicated. There was still some extremely limited use of plate armours in WW1 (notably massively heavy 'sniper proof' combination chest and head shields). This proved a wasted effort, as by that point the weight of the bullets easily penetrated anything able to be carried. (I saw several samples of these pieces at Ypres in the museum there in 2016 - with bullet holes.)


Ok - so what DO you have here?
I've sent back two of your images, marked up.

(green) : The original surfaces have been spray painted black (obviously a modern addition!)
 - There are a few areas that show the original metal surfaces.
 - The rust effect on those surfaces looks to be that you see on mild steel, not wrought iron.
 - These surfaces also don't have any forge scale, all the forming has been via cold bending or hammering.

(purple) : You mention how the visor only can be raised slightly. This would be a very bad design if this was a 'working' helmet. The visor is in fact shaped primarily. as a flat curve (section of a cylinder). It really should be dished (section of a sphere) in a shape that conforms to that of the skull.

(yellow) :  All the plates are formed of the same, very thin, (mild steel) metal stock.
- The metal would be extremely thin for actual wrought iron plates
- You can't really tell in the images, but this appears the same thickness for the body of the skull as well.
These do appear very thin, against the ideal for the purpose of actual combat. This is seen in the visor, which is one of the normally thickened target areas on an armour. the skull plates should also be considerably thicker for the same reasons (you can judge if this is the case?). In combat, most strikes will come to the wearer's left side skull, which commonly is thickened to protect against these impacts.

(red) - These seams look to be arc welds.
- The beading further looks to be stick welding.
- There has been an attempt to grind the welding beads smooth and flush
- The uppermost line of welds appears to have actually burned through the metal - which indicates both not the best work - but most importantly again that the skull plates may be quite thin metal. 
A look to the inside surfaces of those seams will tell you a lot. I expect you will find the lumps of the weld bead.


So - what time frame does this all give us?
- Mild Steel = post 1855.
Wrought Iron was still being produced, in smaller and smaller amounts, up into at least the 1920's - 30's
- Arc 'Stick' Welding = post 1870.
Stick welders are still widely available. Largely supplanted in current workshops by inert gas welding (MIG), which itself is only after about 1945 (which would be definate modern dating).

One of the big indicators for me is the construction of the skull. It has been made of several narrow pieces, each partially dished, as cold hammering, then the segments electric welded to create the sphere of the skull. This is a very modern, 'amateur' approach to creating the required shape.
The historic method is to hot dish the skull from one single piece. That starting plate would have been forged to a modified thickness profile to start with, thinner at the edges, and thicker in the centre. Taking a flat circle and forming it into a half sphere involves dishing in the centre and raising along the edges. Dishing thins the plate, raising thickens it. Ideally the variations in starting profile would allow for a *uniform* thickness overall in the finished skull - after the stretching and compacting of the two forming processes.


'Antique' as a term gets pretty slippery. 'Vintage' may be fair. This could possibly be a late Victorian era 'replica'.

But, sad to say, I think what you really have here is a helmet made by a mid skill grade, modern, re-enactor. Likely some point in over the 1980's or 1990's.

Note : Images of the object under consideration, from the original questioner. Name is withheld for privacy.

Cow Magnets & Phase Changes

This piece sparked by some stories being swapped recently on the Association for Living History Farms and Museums discussion group…

Cow magnets, easily available at my rural farm supply stores around Grey County in Ontario (Canada), have long been part of my blacksmithing tool box.

For those outside the 'Art and Mystery' :
The ideal temperature for quenching (most) cutting edges after forging to shape is what is called the 'critical temperature'. Without going into the science, iron materials change from a rigid solid, into what is technically a 'plastic' at a certain point in their heating. At this point they also stop being magnetic.
Although a skilled smith can judge this by colour and trained eye - the certain way is just to touch a magnet to the hot metal. Just at the point the metal cools enough so a magnet just barely starts to stick? That is your critical temperature.
This certainly a good 'trick' when working in the sun with outdoor demonstrations!

Those long bar magnets many of us used back in public school would be even better (if you could find one).
I recommend my students just get a cow magnet, these run about $5 CDN around here. I've been using the same one for over 30 years for just this purpose.

ok - I see the technical blade makers reading this starting to pout just a wee bit.
It is not that simple :

Noon’s Knives
 https://noonsknives.blogspot.com/2017/03/

Note right off the start - the carbon content (even in small % variations) shifts things considerably here!
This is hardly any surprise to the experienced blade smiths reading. Right of the start - there is clearly no ‘one size fits all’ in terms of ‘perfect’ iron / carbon mixture - for ALL cutting edges.  (a)

As it cools to 770 °C (1,418 °F), the Curie point (TC), the iron is a fairly soft metal and becomes ferromagnetic. As iron passes below the Curie temperature, no structural change occurs, but the magnetic properties as the magnetic domains become aligned. (1)

But leave the details here, and accept the generality of the original quote at the start. (Do remember it was intended to a non metalworking audience - and really was about Cow Magnets, not technical blade making!)


Another Cool Thing:

This was demonstrated to a group of us at Lee Sauder’s ‘Smeltfest’ event in 2008 - by Jesus Herandez.
If you take hot bar into a really dark room, then watch it as it cools.
"At the critical / transition point, the bar will flash to a brighter colour = higher temperature, for an instant." Oh, yea, we all said...
Wow!
As I understood the demonstration:

From 'Iron, Steel and Swords' by Helmut Föll

As the atoms shift from ‘face centred’ crystals / Austenite back to ‘body centred’ crystals / Ferrite, there is a release of energy as they shift over.  (b)

Further Reading?
‘Iron, Steel and Swords’ - Helmut Föll
https://www.tf.uni-kiel.de/matwis/amat/iss/index.html





a) There are a number of past discussions related to this topic on this blog. What the tool is intended for most certainly effects the choice of material. Some combinations of hardness against flexibility, plus other desired qualities (rust resistance) may be possible with modern, exotic (?) alloy types. Often working directly *against* ability to easily forge.

1) ‘Allotropes of Iron’ - Wikipedia
https://en.wikipedia.org/wiki/Allotropes_of_iron

b) Ok, my eyes start to glaze over too.
The best (and by far clearest!) explanation of all this is again ‘Iron, Steel and Swords’ :
Reading Phase Diagrams - part 6.1.2 / 6.1.3

Viking Age iron smelting air systems?

Those following me may be aware that I am participating in the Hurstwic 'Firing Up Ancient Secrets' project, set for August 23 - Sept 5 at Eiríksstaðir in Iceland.
My contribution is both my research into Viking Age iron smelting methods, and my (considerable) experience with an experimental archaeology approach towards understanding those systems. 
I have been doing a lot of background research and pondering about everything related to bloomery iron making during the Viking Age of late * 
The following is modified from a recent communication with a fellow experimental researcher:



Air systems are especially an area of investigation for me.
What I see as the problem is this:
- We can make blooms that almost exactly resemble the ones found in the archaeology. (Understanding there are not that many samples that have been found.) But to do this requires the application of large volumes of air, and high burn rates. (This based on the pioneering work of Lee Sauder from Virginia  )
- There is almost no hard evidence on what bellows might have looked like from the Viking Age itself. Two images from the period, no object remains what so ever. (Be very happy to be proven wrong - if anyone reading knows something!) This specifically true for possible iron smelting bellows - for which there are virtually no indications on type or size at all. Possibly some signs of post holes that might be supporting frames?

I note here that you most certainly can get some iron produced with low volumes of air. This has definately been proven many times by those working at European open air museums, using what are 'Early Iron Age' methods.
But I consider the quality of the blooms created a very important indicator in results.

My own reconstructions of the blacksmithing bellows, based on those two illustrations, creates a twin chamber unit which in working tests produces roughly 120 - 160 litres per minute (based on one stroke per second)
If you compare this to the 'ideal' air flow requirements, this is at best 25% of the required volume - if you are expecting to create a dense bloom that resembles the ancient ones. (For the 25 - 30 cm interior diameter most of us are working with, air in the range of 500 - 800 LpM.)

So:
Most of us in the experimental community use all sorts of different measurements - or no measurements at all.
One standard is 'charcoal consumed over time'. Again, there is no consistent way this is reported, I see a lot of European workers using 'kilos per hour'. Here in North America (again thanks to Lee) the standard is 'charge amount per minute'. The ideal is usually quoted at '5 lbs over 6 - 8 minutes' (so make that roughly 2 kg).
Here we more typically are running at closer to an overall 1.8 kg every 10 - 12 minutes (so about 9 - 11 kg / hour) Our blooms are intentionally on the smaller size (normally 30 kg ore to about 5 kg iron).

The questions are :
What is the air volume produced by the various *theoretical* Norse type iron smelting bellows?

Ideally, to get any kind of understanding of this, individual teams need to undertake some sort of measurements.
- What are the physical dimensions of the bellows unit being used?
- What is the stroke count per minute?
- Is the actual production volume (when hooked into a working furnace) measured?

- What are the physical measurements of the furnace (especially the interior diameter at tuyere)?
- What is the average burn rate over the smelt?

- What is the yield?
- What is the quality of the iron produced?
(This last is so dependent on the quality of the ore being used - it may not prove a really valuable comparison!)




Right now I am working with a group attempting to experiment with a possible Icelandic based system. At present they are intending to build a large, single chamber bellows (more or less like one half of the known Norse type). This has been tested all of once - and I think is not the way to proceed into the Iceland side of the project.

There may be some element of just how the air flows into the furnace?
- A Norse twin chamber (larger smelting size) produces a flow that never stops, but with changes in volume as each chamber is pushed. The delivery pressure can also be modified each stroke by the force of the push. (Consistency a problem). Requires 3 - 4 workers.

Possible Norse Smelting Bellows - Vinland 3

- Multiple Norse twin chamber, small blacksmith size, linked to a central air bladder. The flow never stops, pressure modified by a weight on the bladder. We have tested this system out twice, but the main draw back is the larger number of workers required (6 - 8).

Blacksmith's bellows linked by bladder - SCA 50

- The single chamber being considered by Hurstwic has no historical examples (that I am aware of). It will produce air that starts and stops on each stroke. Pressure can be modified by the force of the push. (Consistency a problem) Requires 3 - 4 workers.

- A 'great bellows' (two stacked chambers, 'double action') is Medieval at best. This will provide a fairly constant blast, pressure consistent (modified by weight on the top delivery side chamber).  I see a lot of people using this post 1300 system  - and calling it Viking Age. Requires 3 - 4 workers

Settlement Era Great Bellows - Williamsburg

- Obviously use of a modern electric blower gives a constant blast (volume and pressure). Solves the labour problem!


Another extremely important element - which will effect the entire design of the furnaces, is the tuyere system itself. (To be discussed in a further posting)


* If regular readers have noticed a sharp decline in postings here over the last two months - this is the primary reason. 
- June was DARC's major demonstration at Upper Canada Village, plus my presentation at the ALHFAM conference.
- July marked a major construction project (upper deck structure and roofing) at Wareham
- August? 
* formal paper based on the ALHAM presentation to be written
* detailed research into iron smelting in Norway and Iceland
* writing a report relating that research to the Firing Secrets project
* preparing a lecture presentation (before the Canadian Ambassador to Iceland!)
* equipment load out and packing for the trip

BIG 'Can O Worms'

...I would like to open that can of worms again and mention that last week we had some visitors from Germany who appeared in full "costume" at our doors. They had very little interaction with our staff and were rather standoff-ish with everyone. As a matter of fact most thought they might have been "real Indians". They actually made some of our staff uncomfortable, especially our own Indigenous staff as the attire showed a lot of skin as it were. Period correct yes, well done yes. Cultural appropriation? What would you do? How would you approach this. I watched and observed knowing that this is quite common in Europe. After some searches on the internet I found that in Germany alone there are some 40,000 people who belong to these "clubs" and spend weekends at a time in encampments or even longer. There seems to be differing opinions from Indigenous folk north and south of the border. Some think its ok some hate the idea.
Any one out there who may add a few worms to this can?

Yours in History
Del 

That message recently started some conversation on the ALHFAM discussion list. *

The following is (slightly edited) from my open reply.
Presented in the spirit of honest discussion.

Boy - Can O Worms hardly scratches this.
... I am going to ask for any First Nation's members reading to be patient, and try to pull back from their own personal frame of reference.





Correctly identifying Staff in any situation is a problem. Who speaks with authority?
In a classic 'stuff' museum, staff get identified through standard dress (uniform), or at least specific name badges. In our living history sites, historic clothes are the identifier. The visitor accepts information provided by those perceived to be staff. (For those working 'pioneer' periods : What happens when Mennonite or Amish visitors show up at your site?)

But spin this out a bit folks.
One very extreme situation provided in the discussion was people showing up to an American 'conflict' related site - with their 'period' firearms in their hands! This obviously represents huge problems in controlling behavior, especially public safety! (Honestly, I could only see this happening in the USA - with firearms. I have seen, any number of times, costumed visitors to Medieval Festivals waving swords around.)
I would bet many of us here have had the situation where they have visited another site (in street clothes) - and intentional or not, end up 'interpreting'. When you are passionate about history, about sharing information, it is hard to hear a question asked when there are no staff around - and not answer it. I wonder sometimes if I have a big (invisible to me) letter I tattooed on my forehead. (I was at the Yorvic Viking Centre, visiting from Canada in street clothes, and had a teacher ask me to explain a set of artifacts to her school group one time ??)
In the discussion following, a number of suggestions were given about how to differentiate between staff and costumed visitors. Honestly, I think the suggestions that shift into some kind of shaming are counter productive. (Issuing bright coloured sashes one suggestion for example). Consider how 'visitors' are signified at government buildings or in industry. I would suggest a stick on label or a lanyard with badge are typical - and this would be inexpensive. Most importantly this would be seen as a 'standard' approach by the individuals (and other visitors as well).


A second element here is about 'bad history'.
Every institution is attempting to control the quality of information, through some level of staff training, a pre-determined standard story. I'm sure we are all well aware of the 'set piece' delivery : "Welcome to the Irish Cabin, representing 1850..." (heard by myself, on Monday at a local museum).
So I would suggest one of the problems with visitors in costume is that the site can loose control of the information flow. Again, I bet many reading have been in the situation where we have heard poor, or outright incorrect, staff delivery at some other museum. How to contribute / correct needs to be handled with great care - but I'd also bet many of us have attempted this. (Honestly - it goes with the profession!)

The big can o worms is : 'Who speaks for the Dead'

'White Indians' : Interpreters at Jamestown Settlement (about 1998)

I state this in that manor quite deliberately. I am not attempting to be offensive. First Nations have real, ongoing, special, reasons to be more than normally sensitive to this specific example. The original situation described outlines first the problems of staff identification, then further, potential 'bad history'. There is this major third problem laid on top to consider.
Being honest - in truth almost * all * of us working as living history interpreters are representing things we are not. I expect no one reading was born before the Great Depression, likely very few before WW 2. We attempt to represent *history*.

I wanted to point this out specifically, because I personally undertake illustrating the Viking Age. This is in effect a 'dead' cultural set. I am Canadian by birth and culture, not even any Scandinavian lines. Am I allowed? By definition my activities are 'cultural appropriation'. This is fine because there are no living community to complain? Who decides on the accuracy of my portrayal?

'Famous Viking' : at L'Anse aux Meadows NHSC - 1996

I most certainly have experienced the 'furry Barbarian' visitor show up at our historic encampments. Good news for us is that these folks, although perhaps enthusiastic, so clearly do not visually resemble our working interpreters that no other visitors were confused. We had a group of 'O∂inist' (White Supremacist) followers show up at one presentation. They left disgruntled, largely because we were 'too boring', ie did not support their distorted views on extreme religion, slavery, and White Dominance.

In the case given that sparked this commentary, Germans especially have a long recent history of 'Native Re-creation', going back at least into the later 1800's. This has represented a true interest, with all the honest distortions possible when anyone attempts to re-create something not of their own birth - and so far removed from their own life experience.

Does any one cultural group 'own' that material culture?


* " The Association for Living History, Farm and Agricultural Museums (ALHFAM) is the organization for those involved in living history including living historical farms, agricultural museums, outdoor museums of history and folklife and those museums - large and small - that use "living history" programming. "