The man who fires neutrons at medieval armour: Dr. Alan Williams on using cutting edge technology to better understand our forgotten past

By Dr. James Hester

The Sciences and the Humanities were not always as isolated from one another as, sadly, they often seem to be today. Fortunately, there are those who remain committed to exploring the wondrous possibilities that arise when the two work together.

One such individual is Dr Alan Williams. Alan is an archaeometallurist: a specialist in the pre-modern processes of creating and working with metals. For over twenty years, he has applied his expertise at the Wallace Collection in London, studying in particular their world famous collection of centuries old arms and armour from around the world in order to shed light on the techniques by which they were made, many of which have been largely forgotten. He is the author of two of the most authoritative works on the subject of metalwork in Europe up to the sixteenth century: The Knight and the Blast Furnace, which explores the production of armour, and The Sword and the Crucible, which investigates the manufacture of swords.

Having spent much of my career in the world of museums, I have been privileged to get to know Alan over the years, and have a great deal of respect for him and his work. Not only do his investigations provide new and deeper insights into already iconic objects in some of the world’s great collections, but they also demonstrate the extraordinary results that come from thinking and collaborating across disciplines. I recently had the opportunity to sit down with Alan to speak with him about his work and his thoughts on interdisciplinarity in today’s world.

Tell us a bit about the work you’ve been doing. Where did it all start?

I started off as a chemist, reading chemistry and metallurgy at university. I got interested in the history of chemistry and in the history of gunpowder. I thought I would just try making some saltpetre – the essential ingredient for gunpowder – and after two years I got a 1% yield. I thought “This is considerably more difficult than anybody seems to admit. Why did anybody bother doing it?” Because you already had a very powerful weapon in the crossbow, why would you bother going through this performance to make gunpowder? But it was made, and made in some quantities by the fifteenth century, and the only conceivable reason for doing this was because with a gun you could knock down an armoured knight, and with a crossbow you couldn’t.

So, I thought, all I have to do is to go to the Tower of London and find out what armour is made of, do a few sums, and my master’s thesis is finished. So, off I go to the Tower of London and I meet Russell Robinson, who was a great curator – he not only studied the history, wrote books, but he also made armour, took it to bits, put it back together, practiced swordsmanship – and he said, “Well, that’s a very interesting question. Nobody seems to know what it’s made of. We did send some to a chemist a few years ago. They did some tests and said it’s all made of iron. Well, we know that, it doesn’t really explain anything. But what do you think you could do?”

“Well,” I said, “the metallurgy would be a better approach than the chemistry.” “Fine,” he said, then he took some bits from his bottom drawer and said, “why don’t you go and find out?” So I did, and that was really where I started. Like lots of research, the more you do, the more you find out, the more there is to find out, and the horizon recedes steadily further and further away.

But eventually I did get enough information to outline what I thought the history of making armour was. I took early retirement and got a position at the University of Reading’s Engineering Department. They were concerned with fracture mechanics, exactly the sort of thing I wanted to do, because I wanted to find out what armour would do. Their concern was mostly what happens when a ship hits an oil platform in the North Sea, but it’s set up to find out problems with impact, and their equipment was perfectly okay for me to test little bits of steel. Finding out what armour actually did, plus the historical metallurgy I’d done, enabled me to try and join the two halves and put together The Knight and the Blast Furnace.

The Engineering Department at Reading closed down some years ago, but I managed to salvage some equipment and set up a little laboratory in the Wallace Collection. The direction our work has taken now is looking at the Oriental Armoury. We started to look at the metallurgy, which is quite different to European metallurgy; it starts from a completely different basis. Finding out what museum swords and armour are made of is rather more difficult, because to find out what a sword is made of, you really have to look at a cross-section. You can put a helmet or breastplate on an inverted microscope and look at the cross-section without doing much harm to the armour. But there isn’t a section available of a sword unless you cut it in two, which tends to make you really unpopular with museums.

At this point, I met a colleague, Dr Francesco Grazzi, who is a theoretical physicist but interested in Japanese swords. We arrived at the conclusion that neutron techniques were the way forward. Neutrons pass straight through metal, unlike X-rays; in fact, they are stopped by organics, unlike X-rays, so they behave really in the opposite sense. For several years now we’ve been taking objects from the Wallace Collection and from various private collectors, analysing them by neutron diffraction, and getting some very interesting results. It’s providing us with a lot of information, which of course has turned up completely new questions which we can’t answer, and we hope to continue doing this.

Can you talk a bit more, in layman’s terms, about the process of subjecting an object to neutron diffraction?

There are a number of neutron sources in Europe, which are mostly set up for theoretical and commercial research. But there is an opening for cultural heritage; we get the beam time that people don’t want, but we’ll get stuff done. The object is put into a neutron beam. Most of the neutrons pass straight through it, but a small amount is scattered. The angle through which the neutrons are scattered depends on what the material is – iron will scatter it through a slightly different angle to iron carbide – and by measuring the results at the different angles, you can see how much iron is there and how much iron carbide is there. Iron carbide is what turns iron into steel. The fact that there’s 1% or 2% of iron carbide within the iron makes iron steel instead, and makes it much harder and stronger. Estimating the quantities of these can tell you what the properties of the steel are going to be.

One of the interesting features of oriental steel is that many of the blades have the pattern resembling watered silk on the surface. This is the so-called Damascus steel – a misleading name, because Damascus probably doesn’t have anything to do with it and was probably just where they were sold.

They have a large amount of iron carbide in them, corresponding to something like 1.5% carbon, which is much higher than any modern commercial steel. For modern commercial steel, the highest normally available is about 1.2% carbon. So it doesn’t really correspond to modern commercial steel, but there’s so much iron carbide present that, with very careful forging, you can retain the crystals of iron carbide. And it is the arrangement of these crystals that forms the pattern which is said to resemble watered silk.

A lot of the blades collected by [Sir Richard] Wallace and his father got a bit rusty or dirty over the years. Dealers, thinking they were making them more attractive, polished them like mad, so they’re bright, shiny white, which they were never intended to be. They were intended to a have a sort of silvery-grey finish, and the pattern is what customers wanted to see because it was their guarantee of a very good blade. So our first problem was actually finding out if there was a pattern there, which we can do by neutron diffraction: we measure the angle through which some of the neutrons are scattered, and that tells you what different crystalline constituents are present in the blade.

Each experiment takes several hours, because most of the neutrons just go sailing right through, so we are hoping to analyse half a dozen objects in a week. It’s not a rapid process. And the commercial rate is about £15,000 a day, so this would soon bankrupt the Wallace. But fortunately it is free, and the Science and Technology Facilities Council (STFC) pays all our expenses, which is good. They run the ISIS Neutron Source at the UK’s Rutherford Appleton Laboratory. In fact, they run most of the big science in this country. They have a colossal budget, and a little bit of it gets spent on cultural heritage.

So, what we learn from this is the carbon content of the steel. If you move the sword through different positions and get slightly different readings, that tells you that the steel is not homogeneous, which means that it is patterned. Even if the surface has been overpolished, if it is heterogeneous, then you know there’s a pattern there. Then you try and persuade the curators to restore the pattern, using lemon juice or something to remove the surface layer which has been overpolished. But that’s a separate issue, and you need to get the curators sitting down and in a darkened room when you tell them something like that.

Does the technology and the approach have any applications beyond metalwork?

Metalwork is a very big field. It works just as well on non-ferrous metalwork. Another technique which has been employed for lots of historical objects is computerised tomography (CT) scanning. Human beings in a hospital might be passed through a scanner, and as they are pushed through, a series of 360-degree scans are carried out, so you have a large number of X-ray images from which suitable software can reconstruct a three-dimensional image of the body.

Neutron tomography works in a similar way. You can pass neutron beams through objects around a 360-degree circle, from which you can reconstruct a three-dimensional picture of what’s inside. This isn’t terribly useful for arms and armour, because they’re plates or bars or rods. The British Museum have been trying to use neutron tomography on Egyptian canopic jars, so you can find out what organs are inside.

Another application, which I think is still being worked on, is trying to read books without opening them; heavily damaged manuscripts which people are afraid to open because that would do more damage. It is possible to scan these with a neutron beam – many scans, because you need lots of information to build up a three-dimensional picture. Medieval inks are based on iron salts and gallic acid from oak galls. Because it contains iron, but the iron of course has got enough metal atoms to respond to neutrons, you can, with enough time, build a three-dimensional image of a closed book. With the right software, you can unravel these images and read the book without opening it. I think this is still an ongoing project, but they’ve had promising results and I think it has a big future.

Neutron techniques are incredibly expensive, and CT scanning is pretty expensive as well. It doesn’t mean that you have to have expensive equipment to do scientific studies on historical objects; you can do a lot of interesting work with comparatively simple equipment. We both know a students of swords who acquired a second-hand Vickers microscope for a few hundred pounds and set up a laboratory in a garden shed. He can get a great deal of information from broken swords, bits of helmets, historical objects, and, if he does not mind spending the time, acquiring the necessary experience of looking at different microstructures and preparing them for microscopic observation. You don’t need a colossal amount of money; what you need of course is quite a lot of patience.

In the time you’ve been doing this work, have both the museum and scientific communities been overall supportive, or have one or the other needed a bit of convincing in order to get things moving?

Russell Robinson was very helpful and encouraged me considerably. Alas, he died in his 50s, which is a loss to the community as a whole. Universities? Well, the trouble with many historians, not necessarily all, is that they tend to think that the amount of knowledge is fixed, and therefore if they share their knowledge, they’re doing themselves a disservice because there will never be any more knowledge to take the place of what they’ve given away. Scientists, I think, realise that the amount of knowledge is infinite – the more you do, the more you find out – and there’s absolutely no problem with sharing knowledge because more will turn up tomorrow. So collaboration has to be between people who can accept this point of view.

I’ve been fortunate in finding collaborators working at ISIS – the Gang of Four, as you might say – among both scientists and historians: Dr Francesco Grazzi, Dr Antonella Scherillo the instrument scientist, myself, and David Edge [Head of Conservation at the Wallace Collection]. And we work together successfully. There’s a professor of history whom I met many years ago who has been very helpful and very supportive, who takes a keen interest in what science can tell him. Other historians tend to be a bit cautious, again I think because they have too narrow a view of knowledge. Scientists? Again some are interested in the history of their own subject; some regard us as cranks and barmpots to be tolerated. So yes, it varies. I think now that we’re getting interesting results from important objects, and we can tell a story about what was done in history, that is helping. We now get a much more positive response at ISIS because we can show that we’re getting somewhere and can tell a story of general interest.

It goes without saying that you’re a supporter of cross-disciplinary collaboration, not just between history and the sciences but across a multitude of disciplines. What needs to happen within communities to make this type of collaboration more common?

It starts in schools, I think. History of Science used to be available as a subject, and the government introduced the national curriculum, and subjects like History of Science were got rid of. Design and Technology is no longer expected for GCSE. Current view seems to be on very traditional, very narrow-minded academic subjects. “Maths and science might be important, but it’s only got to be maths and science.”

You can encourage people to read books. Cyril Stanley Smith was the father of archaeometallurgy. He was the metallurgist on the Manhattan Project, and retired in 1960 as a professor of metallurgy at Chicago. Two of his books are available in paperback, The History of Metallurgy and A Search for Structure, and I think either or both should be put into the hands of every science undergraduate to show them that their subject not just has an origin, but that it also tells a story. There are results from scientific discoveries that change the course of history, that make life better usually, sometimes worse. There are connections at every level in all sciences and history, all branches of human life.

For most of human history the Renaissance Man or polymath, with an understanding of a variety of topics, was the ideal state of an educated person. But more recently, single-subject specialism has become more preferred. And I think it’s much to our detriment.

It’s to save money, of course. If you can get people going to university at 18 and cram them in three years rather than, say, having a baccalaureate at 19 and spending four years or more at university, that’s going to cost more money. So there’s a commercial reason for early specialisation, which is deplorable.

Do you see things coming full circle again?

Everything seems to be judged on business values, so unfortunately I think things are going to get worse, not better. You might try and persuade people that a broader education makes them more creative, and therefore better able to invent profitable schemes and devices. Good luck with that. I think we have politicians, of all parties, who are a product of this narrow-minded attitude. Some just say business values run everything. Universities have been turned into businesses, and hasn’t that been a success? So let’s turn museums into businesses. I can’t see things getting better in the foreseeable future.

Where are things at the moment with your work? What are your plans going forward?

We’re next going to ISIS with some Mughal daggers, and we have plenty more to find out. Some of the differences in the arrangement of the iron carbide in blades I think are connected to forging temperatures. If we can establish this then, because workshop techniques don’t change very much – of course we would need to analyse objects of known origin, which is what we’re trying to at the moment – we’ve got a handle on identifying workshops. We need a lot more data to do this, but I think we are on a promising line of inquiry there.

In the summer, we want to take objects from the Imperial Armoury in Vienna to the nearest neutron source, which is in Budapest. There is only one obstacle. A few years ago, the curator would have just have put an object in his suitcase and got on the train. But he’s not allowed to do that now; he has to use art handlers, and it costs hundreds, if not thousands, to take something from one museum across a border to a neutron source in another country. So what we are trying to do now is find the money from some philanthropic foundation to pay for this.

Establishing the carbon content of the steel, measuring the thickness of a helmet, we would know what is actually there. We can measure the size of the dents which had been made in the side of the helmet, and if you know the strength and thickness of the metal, you can work backwards and get the impact energy. So we can show whether somebody hit him with a lance in a tournament, or just patted him gently with the end of his dagger. But actually reconstructing the history of the helmet would be very interesting and worthwhile, I think.


Dr Alan Williams FSA received his BSc in Chemistry (1964) and his PhD in History of Science (1974) from the University of Manchester. He was a research fellow at the University of Reading’s Engineering Department before becoming Archaeometallurgist at the Wallace Collection. He was made a Fellow of the Society of Antiquaries in 2005.

Dr James Hester FRSA is Head of Ontology & Provenance at Mattereum. He is also an historian and antiquary, having previously served as a Royal Armouries Curator of Tower Collections at the Tower of London.