Hans Theys

 

 

 

 

Hans Theys

 

 

A Big Bang

 

Conversation with Joost pauwaert

 

 

- Five weeks ago, you succeeded in making two bronze cannonballs, shot by homemade twelve-pounders, collide head-on in a fifty-meter-long concrete test-tunnel built especially for this purpose. It took you five years to achieve this. Do you remember when the idea first came to you?

 

Joost Pauwaert: No, I don’t. I do remember in June 2019, sitting here at the kitchen table, making some technical drawings on chalk paper. The first drawing represented the large band saw. The second drawing depicted an older work (Pendulum with Hammers). The third drawing began with two cannons at the bottom, one in each corner, facing each other.

 

- A symmetrical drawing, just like the drawing of the band saw, which has two legs. And then you needed an element in the middle?

 

Pauwaert: I don’t remember. I first drew the cannons and then the two cannonballs colliding.

 

- Unbelievable how much they resemble the final form. Or have you ever seen two collided cannonballs before?

 

Pauwaert: Absolutely not. I suspect it has never happened either. Chances are very small.

 

- Quite extraordinary, I think, because the deformation is difficult to grasp even when you see it in real life.

 

Pauwaert: I did everything to obtain this particular form, of course. 

 

- By looking for the right alloy? 

 

Pauwaert: Yes. First there was the drawing. But afterwards I made sure that the cannonballs did not shatter, but deformed. At first glance you think that matter is missing, but it is not. The metal is not compressed either, that’s impossible. Actually, both balls are swollen at the back, they are expanded. The volume and weight are the same, but the curve of the sphere is larger. The surface is also smoother.

 

- A kind of plasma effect, I suspect. In a plasma, protons and electrons swim through each other. 

 

Pauwaert: We could ask a physicist to explain it.

 

- (Searching the World Wide Web.) It says here that metals are malleable because electrons can easily move from one proton to another. Some electrons move and others do not, creating a solid bond between the atoms. That’s why metals are good conductors as well.

 

Pauwaert: All right, we don’t need a physicist anymore.

 

- In any case, the idea seems to have come from the drawing and not the other way around. It looks like you wanted to design some kind of Napoleonic stationery, with some kind of divine apparition in the center. I suspect you drew the guns first. Then you added the cannonballs ‘flying’ at each other. And from that presumably the central epiphany arose.

 

Pauwaert: I can’t remember.

 

-On which cannon is the drawing based?

 

Pauwaert: On a British nine-pounder. The caption says that they are French twelve-pounders, but that is not correct. Only experts can see that, I thought. The barrel is shorter, for example.

 

- From the drawing a first scale model emerged: a display case with two small guns that fired at each other. On which cannons are the scale models based?

 

Pauwaert: French six-pounders from the year eleven of the revolutionary calendar. They are guns without frills, purely practical. They fall outside the Gribeauval system, to which only four-, eight- and twelve-pounders belonged.

 

- How did you get started on that scale model?

 

Pauwaert: First I went to talk to many people. Robert Monchen, who would later found Pizza Gallery and helped me often at the time, put me in touch with an acquaintance of his, a gun enthusiast who traveled once a year to the United States to a place where blast sounds were recorded for video games. That man referred me to the then director of the Army Museum in Brussels, Paul Dubrunfaut. ‘Ces armes aussi anciennes soient-elles ne sont pas des jouets,’ he wrote in his first email. (‘Those weapons may be old, but they certainly are not toys.’) He received me in his office. He had leather patches on his elbows, glasses and a short trimmed beard. ‘If you ever succeed in making a cannon that can really shoot I will bring you to a shooting range of FN Herstal’s,’ he said. He is retired now. All the men I talked to at the time are retired today. They all had leather patches on their elbows, glasses and a close-cropped beard as well.

 

 

Christmas lights

 

- Who did you talk to afterwards?

 

Pauwaert: Turning the cannon barrels was not so difficult. As cannonballs I used real bullets of 12 millimeter diameter that I had bought together with a pistol. The problem was the required simultaneous firing. How could I make the cannons fire simultaneously? Today everything seems very simple, but then I was looking for some kind of professor of gun science who could help me further. Searching the Internet, I found someone who called himself the city gunner of Malines. His name was Marc Vanhooff. In and around his modest villa you could find many wooden and plastic guns, which he fired with blanks. For ignition, he used some kind of filament. That gave me the idea of using Christmas lights to fire the two guns at the same time.

 

- How were guns lit in the past?

 

Pauwaert: By means of a fuse that you put in the zundhole. The fire in the zundhole then runs to the actual blast chamber. With handguns, you do that with a flint which ignites the gunpowder in the pan. That burning powder generates a second, larger explosion in the chamber. With flintlock weapons, this gives you some delay. You need two explosions.

 

- So the small cannons worked as handguns?

 

Pauwaert: Actually, they were handguns on wheels. My plan was to generate a simultaneous explosion by replacing the traditional, incalculable fuse with a small, electricity-generated explosion in the pan. I found an old-fashioned Christmas decoration with halogen bulbs, removed the glass around the filament of two bulbs, attached them to the back of the barrel, near the zundhole, and put a little bit of gunpowder on the filament. At the same time, I built a sort of test chamber with a glass wall, so we could see and film what was happening. I got bulletproof glass from a retired bank manager. The other walls were made of one-inch thick, solid oak. In that test chamber I did a first test.

 

- How did you aim the cannons?

 

Pauwaert: Just visually, without a laser. I did two tests. The first at home, the second in Oliver Barbé’s gallery. The first time there were two detonations, but one bullet got stuck. On a second attempt, in the gallery, that little gun fired two bullets. Oliver Barbé filmed the second test with an iPhone in slow motion mode. You heard only one bang, but on the film you could see that the explosions were not simultaneous. The flames had not run through the zundhole at the same speed. 

 

- How did you get the gunpowder? Did you make it yourself back then?

 

Pauwaert: During one of my visits to that city gunner of Malines, I asked him where he bought his gunpowder. It turned out he had a large supply. Every now and then I would go and buy a kilo from him.

 

- What kind of gunpowder was it?

 

Pauwaert: It was very fine gunpowder.

 

- Later we will have to talk about different kinds of gunpowder. But first, more about the first shooting tests.

 

Pauwaert: One of the two bullets shot by the same cannon hit the other cannon, which somersaulted. On the outside of the one-inch thick oak tree was a bump caused by one of the bullets.

 

 

Car spark plugs and jumper cables

 

- Then you tried another type of ignition.

 

Pauwaert: In a metal workshop where I was turning a second scale model of the 12 mm guns, I happened to meet a bricoleur who told me that you can easily make a spark with a car spark plug. Besides, those are very precise, which was good for timing. You cannot connect them to the grid or a battery because they require a high voltage. In a car, that is done through the ignition coil, which converts the low voltage to high voltage, about 10,000 volts. But that bricoleur advised me to use a scare wire device, a device that generates current with high voltage but low amperage.

     I had two new barrels turned. I drilled a hole in their rear end and tapped a thread to fit the spark plugs. I connected them with jumper cables and tried to light powder with them. It didn’t work because the spark was way too small. Big enough to light gasoline fumes, but not powerful enough for gunpowder. Then I tried various things: adding a few drops of gasoline to it, for example, but without success. Then I got the idea of spraying ether on it, a trick for starting heavy diesel engines (you spray it into the air intake), but that only worked once. The problem was that the ether evaporated too quickly, thus ruling out simultaneity. This is also how I discovered that it is very difficult to set gasoline on fire. Gasoline only burns on the surface.

 

- In June 1989, I accompanied Panamarenko to the Furka Pass, where we spent two weeks trying to ignite a pastille motor. No matter what we tried, it didn’t work. It was an eccentric, pneumatic engine. Air and gasoline were sucked in and then compressed by moving slats that first enlarged and then narrowed the chambers. Perhaps it was because of the smoothness of the slats? There were bakelite and aluminum ones. They were filed and oiled. Each time we laid the engine wide open. To no avail. Perhaps the position of the ignition was not correct? We tried different positions. Maybe the composition of the gasoline was incorrect? We tried different compositions. Was it because of the altitude? Was the air pressure too low? We couldn’t find out. It didn’t work. Back home Panamarenko understood that the piezo lighter we had used was not suitable for igniting gasoline. Later, he spent eight years looking for a way to ignite the upside-down Suzuki engine of the flying device ‘Hareback’, which failed because for aesthetic reasons the spark plug found itself at the bottom and drowned. He tried all kinds of electronic ignitions, just like you.

 

 

Fireworks

 

- What did you try next?

 

Pauwaert: I discovered that a classmate of my daughter Zita’s descended from a family of firework makers. Her grandfather told me that there were electric fireworks igniters that allowed for simultaneous ignition. I was not immediately convinced because my cannonballs travel 200 meters per second, making simultaneity seem utopian. But in one of my first tests with the large scale models of the six-pounders, I succeeded in making two cannonballs collide. That was in the basement of my then studio. On another attempt in the gallery, I succeeded again, but that time the cannonballs were shattered. The first successful attempt produced two distorted cannonballs that resembled the cannonballs in the original drawing and the two large cannonballs that collided five weeks ago.

 

- Where did you find a fireworks-ignition? 

 

Pauwaert: That grandfather, of course, had already retired and had sold all his gear, but on the net I discovered that you could order it in China.

 

- How does such an ignition work?

 

Pauwaert: There is a kind of dried paste on it. I don’t know the exact composition. It’s more sensitive than gunpowder. It even reacts to 12 volts. It gives a very bright flame like a match and sets things off nicely.

 

-The scale models of the six-pounders had cannonballs with a diameter of four centimeters. The barrels were made of steel?

 

Pauwaert: They were. The wheels were from a marathon carriage and the carriage was made from an old closet that someone had put out for the junkyard, right next to my studio. The wheels on the very first scale models were from a doll’s pram.

 

- How lucky you are to have three daughters. Marie-Puck Broodthaers once told me that her father stole toys from her, including a cart, a small table and a small chair, in order to glue egg shells on them or turn them into works of art by adding his initials.

 

 

Barrels of cast iron

 

- The barrels of the twelve-pounders wer cast, not turned. Why? And how does one cast a barrel?

 

Pauwaert: Barrels of that length cannot be turned because the ‘tolerance’ of the lathes is too low. If you have to drill that deep, the chuck is going to swim a bit and the bore is not accurate. In the 19th century this was not a problem, but today the machines do not allow such deviations. The maximum length allowed for a 125-millimeter hole is forty centimeters.     First I turned a model of the barrel from birch plywood glued together. This is plywood made up of very fine layers. The model actually consists of two halves glued together with three layers of newspapers in the middle, so you can easily split the whole thing in two later. 
I don’t remember how long the turning took, I worked on it occasionally for a few weeks.

     In the end, you are left with two wooden halves of a full barrel. You coat these with a red-colored resin so that the foundry sand won’t stick to them. Then you put one half with the flat side on the table, you build a box around it and you fill the box with foundry sand, which you pound. Then you turn the box over, you raise the edges, you put the second half of the model on top of the first and you add foundry sand again. If you now remove the models, you are left with the mold.      Next, in a separate mold, you make a core, which will ensure that the barrel remains hollow. You need to attach that core both at the top and bottom, because it can be pushed up and bend due to the pressure of the steel flowing in.

 

 

Alloy

 

- The first cannonballs, 12 mm in diameter, were pistol bullets. What material did you use for the forty-millimeter cannonballs?

 

Pauwaert: The little ones were made of lead. I had noticed that they cracked when they hit something. Weird things happened to them. So lead was too soft. I needed an alloy that was compressible but wouldn’t crack. Brass and bronze seemed to give the same result. Brass is an alloy of copper and zinc. Bronze is composed of copper and tin. In the end, I chose a bronze that I assembled myself. All the testing was done in the basement. To get the guns there, I had to disassemble them. That was very laborious.

 

 

Simultaneous ignition

 

- Was simultaneous ignition on point by then?

 

Pauwaert: I hadn’t tested it yet, because I was afraid of damaging one of the cannons. So I devised a test firing arrangement that allowed me to test the simultaneity without the guns firing at each other. I took a thick wooden beam that could rotate horizontally around an axis, like a spiral door. It rotated around a thick, solid bar. On the back I had attached a five-millimeter-thick iron plate. On the front, I poured a layer of molten lead over it. The idea was that a ball arriving earlier would make lateral marks in this lead, because the beam would be pushed away.

 

- Wonderful.

 

Pauwaert: In the very first test, both cannonballs went loose through the beam and the metal. That was a beautiful moment. I was very happy, because I expected it to be a laborious, Christo-like, long road.

 

- Then you made the cannons shoot at each other in the basement?

 

Pauwaert: I didn’t know how precise the shots would be, and I was afraid I would destroy a gun. An exhibition was planned, where I would make the cannons shoot at each other, and there was no time left to make another cannon in case it went wrong. To prevent the guns from destroying each other, I placed them nine feet apart and placed in the middle, at the place where the cannonballs were supposed to hit each other, a five-millimeter thick metal plate that would slow down any poorly aimed cannonball and protect the facing cannon.

 

- What happened?

 

Pauwaert: The ignition was simultaneous, the guns were precisely aimed, yet the cannonballs did not meet in the middle. One cannonball flew through the plate before hitting the other cannonball. Both cannonballs deformed nicely as shown in the drawing. Piercing the plate must have slowed down the fastest cannonball, leaving the cannonballs unbroken. In the next test without a plate in the middle, in the gallery, during the vernissage, both cannonballs shattered and ended up in the wall in the form of shrapnel.

 

- Today the twelve-pounders are protected because they are outside the fifty-meter-long concrete tunnel you built.

 

Pauwaert: Yes, they are. The barrels only extend fourteen inches into the tunnel.

 

 

Concrete shooting tunnel

 

- How did you build that tunnel?

 

Pauwaert: We poured twenty concrete slabs in the middle of a large pasture, measuring 5 x 2.5 meters and about 20 to 25 centimeters thick. The formwork consisted of four planks each. We laid the construction steel mats on stones. About 50 cubic meters of concrete went in. With two construction cranes, we placed those slabs opposite each other like a house of cards and riveted them together at the top with wire rods one meter long and 35 mm in diameter. Then we covered the tunnel with earth, brought in by twenty trucks.

 

- Now that you no longer need the tunnel, you can close the entrance with a barred fence. Then bats can live in it.

 

Pauwaert: In our latest test, a bat already flew out. There was also soil flying around, coming loose from the roof of the tunnel.

 

 

New alloy

 

- The cannonballs of the last, successful shooting test consist of a new alloy. How did it come about?

 

Pauwaert: For the first attempt to fire two twelve-pounders at each other, I used a specially cast cannonball made of lamellar cast iron. This is cast iron in which the unbound carbon takes on the shape of thin discs. It is very hard, but also brittle iron. Stoves and cooking pots are made from it. The week before, I had done several tests with cannonballs made of nodular iron. That is cast iron in which the carbon is spherical, so there is more elongation on it. The cannonballs had a diameter of 120 mm. We shot on steel plates 15 or 25 mm thick. Both the plates and the cannonballs deformed. But since I had the impression that the shots were not precise enough, I had sixteen cannonballs casted that were three millimeters wider: 123 mm. However, due to a misunderstanding, they had not used nodular but lamellar cast iron, which made the cannonballs much harder. When tested, they flew right through the steel plates as if these were made of paper. I would have preferred softer cannonballs, but for the sake of precision I chose the hard ones, which were slightly larger. (Later it turned out that the shots were very precise, only we couldn’t verify that, because we never knew exactly what we were aiming at.)

 

-The canons are outside the shooting tunnel, but their barrels are partially inside. How were you able to aim them?

 

Pauwaert: With a laser. In the back of each barrel we placed a piece of cardboard with a cross. The light had to illuminate the center of the cross. François stood in the bunker and gave directions. I stood outside and tapped on the barrels with a sledgehammer until they were aimed correctly. It was very laborious. Sometimes the whole cannon had to move 2 millimeters. I lifted it with a strap.

 

- The cannonballs from the first test disappeared.

 

Pauwaert: It took a long search to recover one of them. One ball we never recovered. The other one flew to the end of the tunnel and drilled itself at a ninety-degree angle more than half a meter into the ground.

 

- Actually, you are practicing experimental history. Now we can at least imagine the damage such cannonballs can do.

 

Pauwaert: When you see with what ease such a cannonball pierces a steel plate and you think of horses or people...

 

- Finally you managed to make two cannonballs collide without having them shattered.

 

Pauwaert: We spent two days casting cannonballs ourselves, because I needed less hard cannonballs. Not easy. We could use the foundry’s mold, but when you cast bronze, it immediately shrinks. The volume of metal you have to pour into the mold is twice the amount you seem to need. The shrinkage happens very quickly, so you have to use a very wide funnel with a very short spout to slow down the shrinkage. Around midnight of the second day, we finally succeeded.

 

- What alloy did you use?

 

Pauwaert: A variation of aluminum bronze.

 

-Why aluminum?

 

Pauwaert: Regular bronze has a glassy, stone-like structure. Aluminum bronze is more elastic. So is brass. Brass contains zinc. Regular bronze, a mixture of copper and tin, is harder.

 

- Did you use aluminum from the meat pie molds you retrieved from a meat factory?

 

Pauwaert: About ten percent of the alloy was aluminum from meat pots. I also threw in some large brass medals, which contained 40 percent zinc. As a result, there was about 2 to 3 percent zinc in it. The rest was copper. Aluminum bronze has a nice, golden color. By adding a little brass to it, we got a tin bronze color, which I like very much.

 

 

Gunpowder

 

- Can you also tell something about the gunpowder used? Your wife Elisabeth gifted you a book on gunpowder, through which you discovered that you used medieval powder.

 

Pauwaert: I made gunpowder by finely grinding charcoal, sulfur and saltpeter in a polishing mill with grinding balls. Reading the book, I discovered that such a mixture is called flour powder and was mainly used in the 13th and 14th centuries. This kind of powder has several disadvantages. First, it is as volatile as baking flour or powdered sugar, making it difficult to use when there is wind. Secondly, you need more volume, up to three times the mass of the projectile. Thirdly, it is hygroscopic. 
It absorbs water quickly, making it difficult to carry on a field trip.   

     For the tests with the small cannons, I bought ready-made powder with fine grains of 0.5 to 2 mm. Such powder is suitable for handguns, but dangerous for larger calibers because it causes a large spike in atmospheric pressure. Therefore, I made my own coarse-grained powder for the large guns. The larger the grains, the less likely the barrel will explode because the flame can play nicely through the powder.

     If you moisten flour powder and then compress it, you get a more powerful powder. I misted a quantity of flour powder (fifty grams of water per kilogram of gunpowder) and then pressed it into a kind of cake mold with a press I made from a truck jack. These cakes used to be ground, but that’s too risky. We pounded it with a wooden hammer until we had chunks of about seven millimeters. Those went into the polishing mill, without balls, to grind off the sharp edges. In the old days, the resulting grains were further polished with graphite, which closes their pores and makes them less likely to stick together and absorb water. I originally did that too, because it slows down the powder and I hoped it would reduce the chances of a barrel exploding, but since I didn’t see much difference, I now skip that last step. I have great confidence in my gun barrels (laughs). 

 

- How many times did you try before it succeeded?

 

Pauwaert: Our second attempt was successful. I find this hard to say, because it makes the whole thing look easy.

 

- All those tests... Building the small guns. The search for a simultaneous ignition…Then building the big guns. The carriages. The barrels. Building the tunnel. Perfecting the gunpowder. Finding the right alloy for the cannonballs. All the ad hoc solutions you found to problems that arose... You are also working on a parade. How far along are you? I assume you’re going to use the copper rocket you’re soldering now?

 

Pauwaert: The rocket will be seven meters long. It is based on a V2, scale 1/2. I still have to find some kind of cart for it. At the head of the procession I would like to have Napoleonic drummers indicating the ‘pas de charge’. I would also like to have a cart with ringing church bells and cannons accompanying it. Perhaps I could also have all the bells in Ghent ringing at the same time. In the beginning, I also wanted horses with it.

 

- You even fantasized about training a horse to make it accustomed to noise.

 

Pauwaert: I fantasized about that for a while, yes. First they are exposed to loud explosions while they are eating. When they stop responding to that, they are encouraged to walk up to people making noise with pots and pans. If they dare, they are offered treats, so they begin to associate the noise with a reward. My daughter Zita is a passionate horseback rider. But it 
still seemed like a tough job to me. It would be better 
to use horses from the army or the police.

 

- I saw that you have taken pictures of explosions among dead, mutilated trees.

 

Pauwaert: Those trees appeal to me but I don’t know why.

 

- Yesterday I happened to see a documentary about Einstein, which contained the famous image of trees sagging and snapping off under the violence of an atomic blast.

 

Pauwaert: Last week I tried to make a mushroom cloud by filling a 180 cm diameter balloon with hydrogen and two kilograms of gunpowder. A mushroom cloud comes into existence when the rising gases get the same temperature as the environment, but then there should be no wind. Unless your bomb is so powerful that the wind has no influence. In any case, it failed. The balloon exploded during the filling process. For now, it will remain at that one attempt.

 

- Would you like to add something to this conversation?

 

Pauwaert: I would rather not talk about the parade and the rocket in this book, because it is not clear yet.

 

- I understand. But it would be great to be able to end with something we cannot yet imagine. The dream seems as abstract or absurd as the desire to make two cannonballs collide.

 

Pauwaert: When I talk about it, no one seems to understand how this could be art.

 

- I love that. There is an image in front of you that is almost as elusive to you as it is to others. And that image gets you moving, without anyone being able to predict the end result. That can only become a new form.

 

 

Montagne de Miel, 3 maart 2024