Wire: Strip-drawing Method

by Jamie Hall on June 6, 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.

In this post, I’ll be looking at the strip-drawing technique. To do this, a thin, long strip of metal is needed. In the past, this would be made from hammered sheet, which would make it hard to ensure that the thickness and width of each strip was regular. In my initial attempt, I’ve used a strip rolled out from a piece of round wire – I’m aware that it’s a counterproductive way in the long-run, but I want to control as many variables as possible while I learn how to do it.

Starting with an annealed round silver wire of 2mm diameter, I used a rolling mill to reduce it to 0.17mm by 3.28mm. I gripped one end with tongs, and kept it tense as it passed through the mill – this prevented the strip from becoming too irregular. If I was working from sheet, it would need to be hammered very thin, and then cut into ribbons.

Once the strip was prepared, I annealed one end of the strip (about 10mm), so that it could be crimped. If the end is crimped into a “U” shape, it will allow the strip to be pulled through a drawplate, and provide enough structural integrity to be pulled with tongs without deforming. After the first few passes (from 3.2mm to about 1.2mm), the strip appeared to be bending in an irregular fashion. This caused some of the edges to burr, and those burrs caused some kinks. This could probably be reduced by putting tension on both ends of the strip as it is drawn through.

Below 1.2mm, the problems described above disappeared, and I was left with a very even length of tube. I took it down to 0.9mm diameter, but it wasn’t practical beyond that. At 0.9mm, it is still tube, but the join isn’t very obvious. Below 0.9mm, the strip would continue to coil in on itself, eventually forming a semi-solid wire, but this would be quite difficult – gripping such a fine tube with tongs is hard without crushing the tube.

Although I was using a ferrous metal draw-plate, it seems that a wood or brass drawplate would be equally effective – the process doesn’t really change the dimensions of the strip; rather, the strip is curved in on itself. The full length of the strip wasn’t annealed beforehand, and it bends well while hard; it might be that soft silver would be less effective, because it doesn’t sustain tension so well. I’ll try it next time, to compare.

After the drawplates were used, I was left with a very regular wire, slightly curved along it’s length. I annealed it, and then clamped it at one end and pulled the other with tongs. This straightened the wire, and caused it to lengthen very slightly. The next thing to do was test how useful the wire was – it lacks strength, and even as, say, a pendant, any given segment would have to be no longer than 20mm, or it would easily be damaged. In the modern day, it wouldn’t be worth making this sort of wire in silver, because solid silver wire is so cheap. It might be useful for gold or platinum, as they are so expensive. Where the wire would be useful is as surface decoration. It bends well, but the location of the join can effect it. With the join on the inside or outside, the wire bent well over a round mandrel, but a right-angled bend was less effective, particularly with the join on the outside of the bend. This might make it useful for cloisonné or filligree, although the delicate wall thickness of the wire might make risky to solder the metal or fire the enamel.

I’m not sure of the provenance of this technique. In Anglo-Saxon Crafts, K. Leahy suggests that the methods used were strip-twisting, block-twisting and wire drawing. Likewise, Theophilus talks about hammering out wire, or drawing it. The latter is presumably “wire drawing” as we do it today, using the draw-plates described in Book III, chapter 8. In conclusion, this method may not be that appropriate for the medieval period, but it certainly predates that era, and is feasible using the equipment of the middle ages.


Bentiron June 7, 2010 at 00:28

“metal draw-plate”, “brass draw-plate ”
I know that you are trying to convey a difference between a steel draw plate and a brass draw plate but you don’t seem to be succeeding. When did brass cease to be a metal?
I’ll give this method a try in some of my work as it looks interesting. Thanks for teaching an old dog a new trick.

Jamie Hall June 7, 2010 at 07:29

Good point. I’ve changed it to “ferrous metal”; that’s what I meant, honest…

Judy Hoch June 13, 2010 at 12:01

Jamie – It looks to me like you made tubing, not wire. If you were to take 16 g sheet, saw or shear off a square long section, you would have the makings for handmade wire. If then you hammered all square edges down, it would begin to be wire. If you continued, you could make some pretty good wire. IMHO, draw plates were a late arrival on the metalsmithing scene. to lengthen the wire, you would use a cross peen hammer and then return to hammering edges. Or after annealing, you could stretch the wire by anchoring it on both ends and hanging something heavy in the center.
On another comment you made about the edges getting rough, isn’t that because you needed to anneal the piece?

Jamie Hall June 13, 2010 at 12:27

Thanks for your comment, Judy. I’ve added an extra photo to the bottom of the post – it shows the curved and right-angled bends I made with the strip-wire; it behaves much more like wire than tube, presumably because of the join running down it, or maybe because the wall of the tube is so thin. As I was able to anneal it, I suspect I could also solder it, although I would have to be extremely careful. At 0.9mm, it is technically tube, but beyond that it would compress further – I just didn’t have the time to go below 0.9mm.

I am planning to try the hammering method, but before that I want to look at strip-twisting and block-twisting. I’ll probablyalso have a go at using draw-plates without the luxury of using a rolling mill first – your description of the hammering method would be a good starting point for that. I’ll definately try the stretching method – that’s really interesting. Do you leave the weight on for a long time, and let it stretch slowly, or is it done fast?

I disagree about the draw-plates – they were certainly in use by the 12th century in iron for wire-making, and wood for evening out chain links (according to Theophilus). I’m certain that wood or soft metal draw-plates would be suitable for strip-drawing wire. Even if it’s pseudo-wire, it’s so ridiculously easy to use this process that I had to give it a go, and the technological requirements are lower than any other method except hammering.

The burrs and flaking were not really a problem – as the strip-wire got thinner, all of the imperfections disappeared; as you can see in the photo, it’s surprisingly smooth.

Chris Bell June 15, 2010 at 20:38

Take a look at hookupwire.org for all of your Hook Up Wire needs. That includes cutting and stripping, tin dipping, terminating and much more.

BTW, you really know your stuff on this subject!

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