Wire: Hammering Method

by Jamie Hall on August 4, 2010

In April, I did a post on wire-making tools, which briefly touched on methods of wire-drawing. There’s a proper discussion of some of the methods in Gold Bulletin: The Production of Gold Wire in Antiquity, by Andrew Oddy. This time, I’m looking at the hammering method in detail.

Fine Silver Ingot

Of all the techniques for manufacturing wire, this must be the oldest – the requirements for the process are the least demanding, as only an ingot of metal and two hard objects are needed. By the medieval period, the best possible tools were available – an ingot mould, an anvil, and a hammer. In my case, I’ve cast a “bread loaf” ingot in an open sand mould, using fine silver. My previous experiments with wire-making techniques have used sterling, but I felt that the ductility of fine silver would be necessary for this one – if nothing else, the constant annealing and pickling of sterling silver would be time-consuming.

6x7wire

Although Theophilus doesn’t give direct instruction on the hammering of wire, he does mention it often, particularly in the context of preparing wire for other processes, eg. for the organarium (Book III, Chapter 9) and the drawplate (III-52). I assume that he doesn’t go into detail because the production of bar and thick wire would have been central to all branches of metalworking, and was probably considered an elementary skill. In the modern era, it is rare to produce bullion in this way; a wide range of very precise products are available, and even the most traditional jewellers depend to some extent on these industrially produced bars and wires.


Above 3mm, it is extremely hard to draw wire in silver or gold – for any round wire above this size, hammering (and swaging) would have been used. Also, all of the images of drawplates from this period, and those found by archaeologists, have round holes; any square wire would have to be produced with a hammer, as would oval, triangular or other fancy shapes (if they were used at all).

5.7sqwire

The method is a simple one, but it might take me a long time to master it. The ingot is removed from the mould, and thoroughly cleaned. The ingot should be carefully examined at this stage, to check for cavities or impurities; even a small imperfection would quickly spread as the wire lengthens. Using a flat-faced steel hammer, the rough ingot is shaped into a regular square cross-section. Making sure that the ingot has some right-angles gives us good starting point. Once the section is achieved, the wire is gradually reduced. It’s counterintuitive, but at this stage, lots of strikes at different angles are the best way to keep the right cross-section – any mistakes are evened out by doing this. In this context, a ball-peen hammer works as well as a flat hammer, so long as the flat is used to finish the surface of the wire. With skill, it must be possible to do this with fewer, more even strikes, and this would improve the speed of the process; from the ingot to the 4.5mm square wire must have taken an hour, whereas the equivalent modern process, in a rolling mill, would be done in minutes.


Down to 5mm square, it was remarkably easy to keep the wire square – this surprised me, as I’ve always had a bad time with sterling silver – I could never manage to keep it square below about 6mm (a huge difference with this kind of work, as you can see from the photos). After that, mistakes begin to magnify themselves. Looking at the photo of the 4.5mm wire, the left end is losing it’s shape, and proved very difficult to correct. I had a very strong urge to use the rolling mill to correct it, but that’s the coward’s way out.

5sqwire

I then spent a while trying to correct the section. There were three ways of doing this, all with some success. Where the wire had taken on a diamond section, the long axis of the diamond was beaten, giving the wire a hexagonal shape, but from there is could be brought back to square, mainly by pressing the rest of the length (which was already square) flat onto the block, and using the hammer to “transfer” the section along the wire. Lastly, ensuring that the wire was the same thickness throughout was critical to correct the section – if one end of the wire was thicker than the other, it wasn’t possible to “transfer” the square section until it was the same thickness as the other end. Fortunately, I always had part of the wire with a square section. If I hadn’t, I expect that bringing it back to square would have been much harder.

4.5sqwire

I took another photo at about 3.5mm, which shows a roughly square section, although the centre of the wire is a bit rounded off. Around this thickness, I lost and regained the section several times, so I decided in the end to just take a photo, and accept the imperfections. As I continued past this point, the section came and went with depressing regularity, so I changed my technique – instead of trying to keep the entire length square, a chose the best end for hammering, and used the other as a handle. This made quite a big difference, as you can see in the last photo.

3.5sqwire

Stupid though it may sound, reaching this point felt like breaking the sound barrier for the first time – there was a lot of turbulance as I approached this point, and I really wanted to give up, and just run the wire through the rolling mill. But suddenly, it changed, and wire lengthened quickly and evenly. I only took it as far as 2.9mm square, due to time constraints, but at that point, it could be drawn through a drawplate (with some difficulty, as it’s above 2mm, but still possible to draw by hand). I’ll continue to hammer it down, when I have some spare time, and by the time it reaches 2mm, it should be suitable for block-twisting. It might even be possible to take it down to 1mm or less, and then hammer it into strip to make strip-drawn or strip-twisted wire (I’ll be trying the latter technique in my next experiment).

2.9sqwire

If I was repeating this experiment, I would definately try using a larger hammer, to see if that made the process quicker – the question I’m asking here is what made the process suddenly easier; could it have been the weight/size of the hammer relative to the thickness of the wire? There doesn’t seem much point in hammering out round wire below 3mm, as I have several other, better, techniques for doing that, but above 3mm it would be a good test of my skills. If I can find appropriate swages, I might also try using those – I’m not sure swaging would be technique in it’s own right, but it would certainly be useful for truing the section of the wire.


I expect that this preparation would have been the work of apprentices – my own experience is that it is very time consuming, and though I was only partially successful, a well-practiced worker could certainly produce much larger quantities in a day than I could. One thought I had when making my wire was that it could be sped up using two workers (Theophilus makes various references this kind of assistance) – one wielding the hammer, and the other moving and turning the wire. Once a production line was set up, these bars and wires would form the basis of a wide range of jewellery items; it might even be that some workshops would specialise in producing ingots and bars, while their customers focused on fine work, in the way that most jewellers do today.


{ 7 comments }

Bentiron August 4, 2010 at 19:50

Having fun forging are we? It is sometimes easier to go from square to round than to try to keep it square the whole time. This is something I learned while forging steel.
To draw your ingot down from the 5mm square to a 2mm square it would be easier to draw it down to a round rod then to try and maintain a square the whole way. My first draw would be from square to round and then to another square and then to another round and my final draw out would be to the 2mm square shape. Trying to maintain a square the whole time is extremely difficult.
Also to avoid the trapezoid shape you need to rotate your metal one-hundred-eighty degrees to forge on the opposite side, then rotate it ninety degrees and forge, then one-hundred-eighty degrees to forge on the opposite side, then ninety degrees and forge and so forth. I have carried this practice over from iron work but if you find that you are getting the diamond shape again just go to the round again and then back to square.
Even though you are working with fine silver it would be good to anneal occasionally.

Jamie Hall August 4, 2010 at 21:46

I did anneal it occasionally – forgot to include that in my description. I did notice the fine silver harden quite quickly, but it never showed any signs of damage, so I probably only annealled it five or six times throughout. I don’t know how far I can push fine silver, but I wasn’t taking any risks.

Thanks for your advice – I’ll try what you’ve suggested in the future. Is it really easier to make it round? I thought that would be harder. Do you just need to keep hammering the edges formed by the previous strike? I was rotating it in the way you suggested, rather than 90 degree turns, so is there something else I should be doing to keep it square?

Bentiron August 6, 2010 at 19:59

When forging form square to round in steel, I go to octagon, then take it to total round, put it back in the fire, then go to round again, back in the fire, then work it to square. Through all of this it is getting thinner and longer. How does one keep it square? When I first started forging steel it was anything but square. All I can offer is that with lots of forging I became very good at making my long square tapers. Some of them were from 3/4”(20mm) down to 1/4″(6mm) and then I would spiral them. I have seen in various museums Bronze Age jewelry with hammered wire of consistent rectangular profile that was an absolute marvel of workmanship. Here is a bronze arm band that is triangular in cross section that is forged by hand. Years of practice is how the smith got it that way, somehow I don’t think it was his first go at it.

Jamie Hall August 7, 2010 at 20:01

As with so many metalworking techniques, the answer to “how do you do that?” is “with a great deal of care, practice and patience!”

Would triangular wire have to be done on a swaging block, or is it actually possible to make it with just a hammer and anvil? I can’t imagine how that would be done without a block. I should probably look into blacksmithing for information on forging – the scale is larger, but the techniques have probably been kept alive in blacksmithing, whereas they seem rare in the modern jewellers workshop.

zerodtkjoe October 20, 2010 at 12:05

Thanks for the info

RITA AVASSO January 19, 2012 at 15:12

HI,
I AM INTERESTED IN GETTING A TROY OUNCE OF SILVER IN A LOAF FORM….I SEEM TO BE HAVING TROUBLE FINDING THEM….I ONLY WANT ONE TO HANG AROUND MY NECK….I USE TO HAVE A GOLD ONE…BUT WITH TROUBLED TIMES….I HAD TO SELL IT…..I CAN GET THE OUNCE BUT THEY COME WITH THEIR CO. LOGO ON IT AND I WANTED SOMETHING PLAIN AND RUSTIC LOOKING….COULD YOU POSSIBLELY HELP ME?
RITA

Jamie Hall January 22, 2012 at 11:33

I don’t take commissions online, unfortunately – it might be worth checking for small workshops in your area. If you are in the UK, there has to be a hallmark on any silver object of 1/4 of a troy ounce, but rules vary between countries. I think that most cities have a couple of people able to this kind of low-tech, rustic work. Sorry that I can’t be of more help to you.

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