Last Thursday, I took an impromptu trip to Butser Ancient Farm to assist Neil Burridge with some sword casting he was doing as part of a filming project with 360 Production (the guys who make Digging for Britain!) Needless to say, the casting went well, Neil produced an expertly delivered spiel on bronze sword casting, and everyone was very happy. It was after the camera crew had done their thing that we turned to the main event of my day – that is, breaking the sword into fragments.
Firstly, I’m going to insert a proviso in here: this was not an elaborately planned out experiment. My “real” experiments are fast approaching, but this was simply an opportunity to play about with variables and react accordingly to things as they happened. I knew from past experiences that the easiest way to break a sword was to heat it and hit it. As a rough guide I’d been told around 5-600°C but no exact temperatures had been monitored, so part of my interest was to investigate what temperatures were needed to successfully break a sword.
The sword was a Ewart Park form and was left as-cast from the morning’s work. Neil has a fantastic little kiln he uses for heating clay moulds so we placed the sword inside this, supported above the charcoal, and positioned a temperature probe above the sword. We were aiming to heat the sword to approximately 550°C. Meanwhile, we gathered together the rough equipment we’d need: a block of wood to rest the sword upon, a wooden baton to smack it with, tongs to hold the sword and (of course!) safety gloves and goggles.
Once up to temperature we removed the sword from the kiln – it was red-hot towards the tip, but still a dull grey at the hilt, which I suspected meant we would be able to break the tip, but not the handle. The aim was to break as much of this sword as possible. Neil lifted the sword out and quickly placed it on the block with the tip end protruding, handing me the tongs and, in a suitably Thor-like fashion, I brought down my baton…
The tip instantly broke off. I quickly shifted the sword along again and struck a second time. Again the piece came off without trouble. The metal was still glowing at this stage but cooling fast so I hastily worked my way along the blade. Whack! Whack! Whack! All the way along the sword. Naturally, as the sword cooled, more strikes were needed to break it. I separated the hilt from the lower blade and then to my complete surprise I was able to break even this in half, separating the tang from the shoulders. Needless to say, all of this was over in a matter of thirty seconds.
Exulted, Neil and I let out a cheer. Steaming away on the floor of roundhouse were, for all extents and purposes, Bronze Age fragments, not that dissimilar from those I’ve been studying in the museums.
My fragments were of inconsistent sizes, no doubt due to my inexperience and desire to perform my task too quickly. Nonetheless, l was happy with the results.
Those of you who are familiar with Neil will know he never goes anywhere without a selection of swords and out of nowhere he unexpectedly produced a second sword for us to break.
The ease with which I had been able to break the first sword made me suspect that the heat at which a sword reaches breaking point is probably much lower than 550°C. One might not be able to break the whole thing in one go, but you could certainly spawn fragments. With this sword we chose to be conservative and aimed for 500°C. We also decided to break it from the handle to the tip, and my personal goal was to get consistently-sized fragments.
We repeated the process as before, heating up the sword in the kiln, removing it once red-hot, and placing it over the block. After fumbling with the tongs I got a good grip and struck the hilt. The sword didn’t break – it simply bent. I struck it again and again, only achieving a greater bend. My fumbling with the tongs seemed to have taken too long and the metal had cooled quicker than I had expected.
Undeterred, we tried again, heating the sword to red-hot around 500°C and striking it. Again I succeeded only in bending the sword. It now had a significant curve along the whole length. On to the third attempt, we increased the target temperature to 550°C, hoping that we might finally get some fragmentation. This time Neil held the sword in place while I struck the hilt end. It was only after several strikes, a significant bend and a tremendous Thwack! that the first fragment finally broke off, exploding across the roundhouse in the process. I managed to break off two more pieces after this one, but it took a great number of strikes with significant force.
You may be wondering: why was the first sword so easy to break, while this second proved so much more difficult? The answer lies in the metallic composition. The composition of the first sword was 8% tin and 2% lead, while the second was 12% tin and no lead. Clearly the lead has a significant impact in the dispensation of the bronze to break: as lead doesn’t dissolve in tin-bronze, it creates natural weaknesses along which the sword could break. I was aware this would probably have an effect, but it’s fascinating to be able to see the extent to which it impacts the breakage.
In a final attempt, we heated the second sword to about 650°C, causing it to produce an orange glow, and I was finally able to break it down into a further five fragments. This was by no means as easy as with the first sword though, and required much more effort on my part with the sword became quite bent and deformed in the process. On the plus side, I was able to keep the fragments at a more consistent size this time.
There’s obviously so much to learn and digest from this experience, and even over a week later I’m still trying to process all the answers – and, more importantly, the questions – this impromptu experimentation has raised. For now though, I’m pleased with what my fragments are teaching me, and excited for what I’ve yet to learn.
N.B. Since last Thursday, I’ve actually found out that there’s someone out there exploring this for their undergraduate dissertation, and if anyone has anything to offer regarding heating and breaking up swords, please do get in contact!
I must, as always, thank my Master Bronzesmith, Neil, for his assistance on my ongoing project. It wouldn’t be half as interesting without him! My thanks also go to Butser for having us there and any of the volunteers who curiously observed what I was doing – it’s always a pleasure to speak to people who are interested!