There’s an interesting conference coming up this summer. I’m looking forward to seeing other tool-loving archaeologists there!
23-26 Jun 2016 Belfast (United Kingdom)
There’s an interesting conference coming up this summer. I’m looking forward to seeing other tool-loving archaeologists there!
23-26 Jun 2016 Belfast (United Kingdom)
I have a fascination with bellows. We know they had to have existed in the Bronze Age, but unfortunately they are also constructed of ephemeral materials, so none have survived into modern times. The only physical evidence we have consists of fragments of tuyeres. An Egyptian painting from the Tomb of Rekhmire, from 1450 BC shows a man using pot bellows that are operated by hands and feet. There are also Chinese documents depicting the use of box bellows. But bellows, after blowpipes, are likely to be one of the earliest forms of delivering air to the furnace.
Until a set of bellows is uncovered preserved in a bog somewhere a lot is left to the imagination. How big or small could they be? How can the valves be altered to be more efficient? How heavy should the leather be? Should sturdiness trump suppleness? How are all the parts held together and made airtight? Bellows are one of the most essential pieces of equipment that we have for casting bronze and yet very little information is available about their use and construction from the community of experimental archaeologists and reenactment groups.
Over the years I’ve seen many different shapes and sizes of bellows and always thought that a forum where bellows design and use could be discussed would be invaluable for people to share ideas and experiences.
I would like to invite others to share photos of the bellows they’ve made on this site. This could be a welcome forum for discussing the pros and cons of different designs, what worked, what didn’t. Of course any news of archaeological bellows or tuyeres discovered would add to the fun.
To start, Martijn van Es sent me some photos of a set of bag bellows he made and photos of a new set he recently completed using the tutorial on this website. Martijn casts bronze at the Bronzezeithof Uelsen and Het Bronsvuur – The Bronze fire and is active on the web and Facebook discussing Bronze Age casting techniques and projects that he’s involved with.
I welcome others to send in photos of their bellows, and not just bag bellows. Any bellows that could be considered to fit in with what we know or can surmise from archaeology would be interesting for this forum.
Bone needles are one of those things that are a useful part of any experimental kit. They are easy to make, durable, and work better for sewing leather and hide than many steel needles. If they do break, then it’s easy enough to cut off a new bit, drill a hole and sand it down to a glossy, slender tool. The best bones to use are the long bones, a humerus or femur.
Recently a particular bone needle made the news. A 7 cm needle made from a bird bone was found during an excavation in the Altai Mountains in Russia. You can read the full article here. Finding a needle in an excavation is difficult enough, but finding one intact after 50,000 years is extraordinary.
However, in this context this needle is much more than just a needle. First we must think about the technology and tools that went into making the needle. It had to be cut and shaped with stone tools, and then there’s drilling out the eye. Once we start thinking about making something as simple as a needle, suddenly an entire toolkit appears, and then there’s the other direction: how was the needle used and what was it used for? Materials such as leather, string, and textile rarely survive in the archaeological record. Could the Denisovans have been sewing hides into clothes? Making shoes? Sewing smaller skins into something larger such as blankets or tents? A world of missing material culture suddenly becomes imaginable.
Small things like this needle should put to rest the image of the “caveman” with ragged animal skins. These people were likely to have been sewing clothing!
Tuyeres are the tubes that bring the air from the bellows to the furnace. They can be made of wood, ceramic, PVC pipes, copper pipes, really whatever you can come up with that will do the job. They are usually connected to the bellows, but in some cases they can just be set close enough that the air is delivered through them to the furnace. If you have a set of two bellows, the tuyeres are in a “Y” shape, with two ends connected to the bellows that connect to a single end going to the furnace.
Archaeologically there aren’t many remains of tuyeres. There are some fragments of tubular ceramic objects that had evidence of burning on the end. However, the best example is a wooden one recovered from a Danish bog. This was the same sort of “Y” shaped one described below.
One of the problems of working with kids is that they are so fascinated with flames that they sometimes don’t realise that the bellows aren’t the part that supposed to be burning. So I’ve been working on making a couple of new sets of tuyeres.
I’m under a deadline for one set, so this one is a quick and easy version. I pulled a good sized forked branch from the woodpile and cut the ends so they were fairly even. Then I got a 22 mm spade bit (aka: a flat bit). Then I just clamped it into a vise and drilled into the flat ends of the wood until the holes met near the centre. I removed the bark, rounded off and sanded the ends. I don’t want any bark that will work loose over time, or any sharp edges that will abrade the leather.
These will be connected by leather tubes to the bellows and held in place by strips of rawhide. Skip down to the section on putting them all together for the details on that.
Note: Save that sawdust you’re generating with all that drilling. It will come in handy for making moulds!
The next one is another wooden tuyere for a new set of bellows I’m making. It’s larger, so the spade bit isn’t an option. Instead I cut the wood in half lengthwise and then carved out the inside with a gouge. It’s all handwork, so it takes longer, but one advantage is that the diameter of the air holes isn’t limited to the size and length of the drill bit.
The first step was to trim the branches and strip off all the bark and then saw it in half. Once it was cut, I marked off where I would carve out the centre and went at it with chisels and gouges. I made the interior as smooth and as even as possible. However, I don’t smooth the surfaces that will be glued together. They already fit well and the rougher texture will help the glue bond.
If your tuyere might be placed close to the furnace (as mine accidentally was), it would be a good idea to make a ceramic extension. This is just a tube made of the same ceramic you used for making the furnace or moulds. It can be fit to the end of your wooden tuyere with leather and rawhide, as described below, and the end can go straight into the furnace. The only problem I find with ceramic tuyeres is the possibility of them breaking when being transported or if someone steps on them.
At the Terramare Village in Montale, the tuyeres they use there have a 90 degree bend. The tuyere sits on the edge of a small, shallow furnace and blows air straight down onto the charcoal. It’s an Early Bronze Age design and does get hot enough to melt bronze and copper. If you don’t have much space for a furnace this would be an ideal solution. It’s also worth experimenting with different types of furnaces and set-ups to get an idea of how many solutions there are to the basic question of how to melt and cast metal.
I’ve also made tuyeres using the stems of Japanese knotweed. The stems are hollow, similar to bamboo, but much softer. The plants can get over an inch in diameter and several feet tall. The stems can be easily cut with a knife, small garden shears, or secateurs, and then the membranes between sections can be broken using a straight stick. Note: Japanese knotweed is a controlled invasive species in Britain. Any fragment of stem, leaf, or root will take root and start a new plant. They are almost impossible to get rid of once started. When I find a large stand of knotweed, I strip off any leaves and excess stem and leave them there. If I need to trim off any more once I’m home, I put it in a plastic bag and then put it in the bin.
As I said earlier, tuyeres can be made of anything that will get the job done. If you don’t need to have that “authentic” Bronze Age look, you can quickly whip something together with PVC plumbing or copper piping. It wouldn’t be glamorous, but as long as any flammable or melt-able parts are kept away from the heat of the furnace, it should get the job done.
At the EAA in Glasgow, I saw a poster showing the reconstruction of a beautiful horse-headed ceramic tuyere by Katarina Botwid of Lund University. You can see the tuyere in action here.
The tuyere still needs to be connected to the bellows. I usually make tubes of leather that fit the tubes coming out of the bellows and the ends of the tuyere.This allows for some flexibility and gives you a bit more distance from the furnace.
Then I tie them in place with wet rawhide. Once the rawhide is dry, they are about as secure as you can get. If the leather is soft, the tubes have a tendency to twist or collapse, so a nice solution is to get some green willow twigs and roll them into a spring. Fit them into the tubes before doing the final attachment and they’ll keep the leather tubes open and prevent them from twisting.
By the way, if you have a hard time finding rawhide lacing, buy a rawhide dog chew. Soak it in a bucket of water overnight and then cut it into long strips while it’s still damp. If you don’t need all of it right away, let it dry out. Then when you need it again just soak it for a few hours and it will be nice and flexible again.
This month (October 2015) I had the great adventure of doing some bronze casting with Il Tre de Spade (The Three of Swords) at the Archaeological Park and Open-Air Museum of the Terramare in Montale. The museum is located just south of Modena and recreates Bronze Age houses surrounded by a palisade and a marsh, appearing as it would have in the central and later phases of the Bronze Age there (1600-1250 BC). The museum hosts demonstrations and activities, along with a recreation of the original excavation.
The houses are nicely furnished, with well laid out areas for cooking, sleeping, food storage, and workshops. One house has a workbench for wood and antler working, along with weaving and other crafts. The other has a metalworking workbench with stone anvils, moulds, bellows, and all the needed kit stored neatly on shelves and a work bench. Unlike the recreated roundhouses that are often seen in the UK, you can get a good idea about how the ancient people lived here and where they put their all the things they used in every day life.
(Click on the thumbnails here to see a larger version)
I had been invited to join the casting demonstrations by Claude Cavazzuti, who is also part of EXARC. He is one of Il Tre di Spade (along with Pelle and Scacco) , who were some of the first metalworkers at the museum after it opened several years ago. They do regular demonstrations (sometimes with hundreds of visitors per day) and also run workshops that introduce people to Bronze Age casting and metalworking with a focus on the Middle and Recent Bronze Age (1700-1150 BC) of Northern Italy.
The furnaces there are small clay-lined trenches about 25 cm deep and 50 cm long, something that would be nearly invisible archaeologically and easily interpreted as a cooking hearth (and really, there’s no reason why they couldn’t be both). The furnaces heat up quickly and work efficiently. The charcoal is concentrated around the crucible with more warming beside it so that the fuel is hot before it gets raked around to cover the crucible.
My first new introduction was the bag bellows. They were larger than I have used in the past, and made of heavier leather. They put out an enormous volume of air, but also their size allows the person pumping the bellows to sit on a low stool. One nice innovation is that they put a large stone in the bottom of each bag. That prevents people who are new to bellowing from lifting them too high and causing the bags to collapse.
The real challenge for me was the valve and the way the bellows open at the top. The bag bellows I’d used before have straight sticks in the handles that either open parallel to each other, or are hinged at the back to open like a “V”. These bellows have two sticks on both sides, so that they open into a diamond shape with the wide part opening where your hands hold the bellows. It took a little bit to get used to them and to figure out where best to position my fingers. I never did get it quite tight enough and could feel a bit of air blasting on the back of my arms, but they still delivered a powerful amount of air. The tuyere was a large clay tube that curved downwards at a 90° angle, and was positioned so that it was directly above the crucible. This mean that the charcoal had to be moved frequently to keep the crucible covered. Without the layer of charcoal above, the air coming from the bellows would cool the metal in the crucible.
The crucibles are a flattened dish-shape, with some that were larger and a bit more of a bowl shape to hold more metal. They have a tab on one side that is used as a handle. The crucibles have a small lip for pouring that causes the metal to pour more quickly and flow out in an arc, rather than almost straight down like the triangular bag-shaped bellows used in Britain. It took a little bit of getting used to the trajectory of the metal in order to get all the metal in the pouring cups.
The tongs they use are beautifully crafted from wood and cord. They are kept in a bucket of water to keep them from burning when holding the heated crucible. The entire organisation of tools and materials is efficient and elegant, and there is nothing that would not have been found archaeologically from this period.
For the first demonstration a sword was cast into a sand mould. The sand they use is local, and perfect for casting. Commercial casting sand consists of fine sand and dry bentonite clay. The sand from the Po River delta is exactly that, sand that has been reduced to almost a powder by erosion, combined with clay and silt that has been washed into the river. The Po River sand leaves a much finer texture on the finished objects than the coarser commercial sand that I have used here. Looking at the quality of the sand, I could imagine how different sands might affect the regional quality of casting, and might even have had value as a commodity.
The mould for the sword was made using the standard cope and drag method, with the pouring cup on the side of the sword, rather than pouring from the top. A large vent was also placed at the tip of the sword. The mould was placed at an angle. As the crowd gathered and settled onto benches under a marquee, Claude explained Bronze Age metalworking techniques and then the sword was cast. Everyone was impressed and even more so when the sword was taken from the mould.
After the demonstration was done we started up a second furnace for the workshop. For this one we used the stone moulds that were on display in the house. The moulds were made of a very fine grained local stone, the same that had been used by the Terramare circa 3500 years ago. The moulds were warmed next to the furnace and then strapped together with leather strips. We took turns bellowing and pouring. The shallow crucibles mean that the pouring has to be done more quickly than with deeper crucibles. They cool quickly, so there is little time for dragging out charcoal and skimming. Once the metal was molten, we gave it a quick stir with a stick, pulled the crucible out with the wet tongs, and poured the bronze into the mould while holding the stick across the top to keep the charcoal back.
Sickles, knives, and daggers were cast. Later we moved on to using sand moulds. I borrowed one of the antler spindle whorls from the woodcarving house to see if I could try casting that as an experiment. It worked sort-of. It will take a bit of work to get finished up, but I think with a couple more tries we could have got it spot-on.
I was wearing my bronze torc bracelet that day and one of the new people wanted to try casting that. We used it as a model for a sand mould and after a couple tries, we got a cast that made a perfect duplicate.
While we were casting, more tour and school groups came through to watch more casting demonstrations. School kids also had the opportunity to make their own copper bracelets. There was a square of tables set up with small stone anvils and hammerstones. Punches and chisels were available so they could decorate the strips of copper to make bracelets in patterns that would not have looked out of place in a Terramare village.
Often after the casting is done for demonstrations the bronzes are taken home and finished up using drills and angle grinders, but not here. We had a relaxing time using wet sand on the hard, fine-grained anvil stones to grind off the flashing and excess metal. Some smaller stones that had a coarser texture could be held in the hand and used for working the inside curves and corners. I’d brought my small socketed hammer along and we used that to break off some of the metal, too. Between light hammering and patient grinding, the daggers were smoothed rather more quickly than I would have expected.
It was a great day, and one that was full of new experiences. It was particularly interesting to see how much variation there is in doing the same tasks and getting successful results. The different types of bellows and crucibles make for differences in how tasks are performed. Other small acts show variation between different metalworking groups. Tasks such as turning the crucible over to remove dross and leftover metal after casting was done into the furnace here, where in Ireland we have always done that next to the furnace. These are small things that could be seen archaeologically if excavation is done carefully, but also shows how customs and metalworking traditions develop with regional differences.
Next month I will be moving to Modena and will be in the vicinity of the park. I hope to do more casting there and to learn more about the Early Bronze Age metallurgy of Northern Italy.
A special thanks to Il Tre di Spade, Claude, Pelle, and Scacco and the staff at the Parco archaologico e Muse all’aperto della Terramare for inviting me to participate in casting. I would also like to acknowledge Markus Binggeli & Markus Binggeli who are masters of bronze casting and replicating ancient metalworking techniques. They are mentors of Il Tre di Spade, and provide both inspiration and technical expertise for experimental archaeologists.
If you’d like to learn more about the Early Bronze Age in the Modena area, the work of Il Tre di Spade, and the Terramare Open Air Museum in Montale you can find links below.
Italian language sites
English language sites
Il Tre di Spade also have a Facebook page.
I love living in Britain, but without a visa, it’s almost impossible to live here. Unfortunately that means finding a job in a very tight market and no options for any freelance work. My best option is to move onwards to Italy. I’ll miss wandering in the Peak District, but I will have the opportunity to do some casting with friends at the Archaeological Open Air Museum of the Terramare in Montale, just south of Modena.
I’ll also use my time there to get caught up on writing. I have a lot of articles to write, both based on my thesis and on the work I did with the Staffordshire Hoard. While these won’t pay the rent, they will serve to get my name in print and make me more marketable in the job world. With luck, I’ll be able to return with a job or a post-doc. Or maybe… I’ll be an itinerant metalsmith, travelling around pouring bronze, sharing ideas, and showing off the magic of molten metal.
I’ve started a Go Fund Me campaign to help with the expenses of moving while I get back on my feet. Check it out. I do have some nice gifts for contributors.
I have done a lot of work other than experimental archaeology, including illustration (both in traditional media and electronic), fine arts, metalwork, and jewellery.
As part of my PhD thesis I needed to draw different types of socketed bronze hammers. Here are a few that were done in pen and ink.
Most recently I have done some drawings of the embossed foils of the Staffordshire Hoard in order to depict reconstructions of the assembled panels. I have included one of the digital reconstructions below. Unfortunately much of the work I did will not be available until the data is released publicly. In the meantime, some of the illustrations and digital reconstructions I did for the Staffordshire Hoard are available here.
Much of my commercial work has been for the science fiction, fantasy, and role-playing game market. I’ve also done a number of wildlife illustrations. These are created in a wide range of media including ink, watercolour, oil, and computer generated images using programs such as Paint Shop and PhotoShop.
I have been far behind in keeping up with my website and blog because I took on a major project working on the Staffordshire Hoard. Because it was a short term contract, I opted to commute from Sheffield to Birmingham. It made for long days, but it was worth it.
My job was to assemble the fragments of embossed sheet metal. I’m proud of the work I did for the Hoard and for Birmingham Museums. There are some articles and blogs that have highlighted the work I did there, with more to come.
The articles and video below go into greater detail about the work I did on the Hoard and have some good photos of a few of the embossed sheet metal foil.
The conservation of the Hoard has won a major award (November 2015). Check out the video The ICON Conservation Awards.
An article I coauthored about working on the hoard published in Journal of the Institute of Conservation is available here: The importance of multidisciplinary work within archaeological conservation projects: assembly of the Staffordshire Hoard die-impressed sheets
Last summer I had the pleasure to assist Dr Eleanor Blakelock in running a week-long seminar in archaeometallurgy and experimental archaeology at the Sedgeford Historical and Archaeological Project (SHARP) in Norfolk. The current excavations are focused on two areas of an Anglo Saxon village, however their “primary objective is the investigation of the entire range of human settlement and land use in the Norfolk parish of Sedgeford”. The excavations have been going on since 1996, and the organisation provides comprehensive teaching in a wide area of archaeological subjects. You can read all about the project here.
Last year they began a new course in experimental metal working. We built furnaces, made moulds, crucibles, mixed alloys and cast bronze. We even got some local ore and smelted iron. It was an intensive week and the hottest one I have experienced in England.
During the event, Ellie took some videos of us in action. The first one shows us building a casting furnace and a pit for heating the moulds, and then follows us through the casting process.
One interesting phenomenon of the week was how we became separated from the rest of the SHARP community. We were given our own space that wouldn’t interfere with the the trenches or the campground. The first two days when we were building furnaces we kept to the same schedule as everyone else. However, once the casting began we couldn’t stop for meals or keep to the schedule that everyone else had. One of our group would come down and bring back food for the rest of us. We were effectively isolated, although the others knew where we were from the rising smoke. Later when we started showing up with freshly cast bronze jewellery there was a bit of envy and wonder. In the space of a couple days we had gone from being part of the community to the people who were “over there” with special knowledge that didn’t conform with regular schedule or tasks that everyone else did. We kept odd hours, were continually covered in soot, but had become somewhat wizard-like in our knowledge of metalworking (not to mention regularly getting out of kitchen chores!).
On the final evening, everyone joined us for the iron smelt. The week had been intensely hot so we started the bloomery furnace in the afternoon, after the heat of the day. As the sun set and most folks had finished their supper, they came by to see the furnace in full swing with fire shooting from the top. Of course everyone wanted to take a turn at the bellows! It was a magical evening. Stories were told, and mysteries presented. In a way it was an initiatory experience for the archaeologists who signed up for the course. It was hard work, but they learned the secret knowledge of the smiths and have stories and their bronze castings to prove it.
The course will run again this July. If you’re interested in learning more about the course or being part of the excavation sign up on the SHARP website.
When I’m casting metal, there’s not much time for contemplation. I’m either pumping bellows, tending charcoal, instructing others, or getting ready for the pour. Finishing the stuff I cast is another matter. There’s a lot of handwork that doesn’t involve concentration. Lately I’ve been carving a new set of tuyeres and hafting a palstave, which means a lot of sawing, shaping and sanding.
Today while I was using a rasp to even out the handle, I was thinking about an incident in my rebellious youth. In the late 50’s and early 60’s the women’s movement hardly existed. Young girls were taught be polite and prepare for a life of domesticity. Even with no knowledge of feminism, that never sat well with me. I was an unrepentant tomboy. Girls were forbidden to wear trousers to school, so as soon as I was home I changed into jeans and more often than not, I’d get into something that meant the knees were torn out. My mother and those in charge of my life despaired of me ever becoming a proper young lady.
The incident that stuck in my memory was the day in first grade when the class was divided up. The boys got pieces of wood to make toy airplanes and the girls got some handkerchiefs to made dolls. I was never one for dolls, and I enviously watched the boys assembling their airplanes. Crossing the line to the boys half of the room would have been unthinkable.
So, I watched every step of what they were doing and when I got home, I got out a hammer, some nails, and scrounged some pieces of wood. It wasn’t as nice as the pre-cut pieces of wood that the boys had in the classroom, but I made an airplane. I even found some sandpaper and discovered my dislike of sanding. Sanding was boring and slow, but I wouldn’t be outdone by a bunch of boys. By the end of the day I figured I had two skills. I could make dolls and I could make airplanes. What I didn’t realise at the time was that I also was able to learn by observation and without being directly instructed. It was also one of my first steps at ignoring the barriers set up to prevent girls from making airplanes, or whatever else they wanted.
I’ve made my peace with sanding. It’s no longer a necessary evil, and instead I’ve found the time spent is good for meditation and reflection. The final satiny surface also shows a pride in artisanship, something that I think a Bronze Age smith could relate to.
Making wooden airplanes and experimenting with bronze axes push the boundaries of how we learn and what we know. Experimental archaeology is one way that I continue to question authority and explore the distant past.
I finally got the fibulae I cast in Dublin last month finished and fitted with pins. They polished up nicely and look a lot more shiny than their counterparts in museums. I still have a hammer and a couple other castings to clean up. Meanwhile a new batch of waxes are in moulds and if the weather behaves they could get cast up in the next couple weeks.
There’s even a slow motion film of one of these guys being cast thanks to the folks at UCD.