Hardening Silver Wire

15 03 2015

When we were kids, we would open paper clips, bend them back and forth, and see how long it took for the paper clip to break. We thought that by bending the wire repeatedly, we were making it soft enough to break. Actually, though, the opposite was true. When metal is repeatedly hit, twisted, or bent it becomes harder, which makes it brittle enough to break.

This is important to understand when working with silver wire. Pure silver has all of its atoms in a lattice structure, much like crystals. With all the atoms lined up in straight rows and columns, the silver is very flexible and soft. This is why, for example, fine silver (99.9% silver) is not a good material for chainmaille. The rings won’t hold their shape and will open, causing the chain to fall apart.

Making Silver Harder

To make silver wire harder, you have to distort that lattice structure, meaning break down the large crystal structure into much smaller structures, so that all the atoms are not in straight rows. Sterling silver (92.5% silver) solves this problem somewhat. Sterling silver is an alloy of silver and (usually) copper. With the different size atoms, the lattice structure isn’t as perfect, and the metal won’t be as soft and flexible. Even so, however, sterling silver can be quite soft, just not as soft as fine silver.

Sterling silver can be hardened several ways, the most common of which is repeatedly pulling the wire through a draw plate or some other materials, even cloth. (If you buy “half-hard” or “hard” silver wire, the wire may have been hardened this way. It may also have been heated to a specific temperature that allows the atoms to flow back into shape.) You can also bend the wire, such as by making wire coils. If you are making large coils, such as for storing the wire, you will have to do this many times to make any significant difference. The tighter the coil, the more the atoms get out of line.

For many jewelers, the most common method is to beat the wire. This includes hammering the wire or placing it in tumbler. When wire is beaten, that lattice structure begins to break apart, and the wire becomes harder. For example, in a tumbler with hard tumbling materials (I use steel shot), the wire is very lightly hit by the tumbling material, but it happens so many times that the wire will become harder.

With chainmaille, when closing rings, I twist the ring back and forth (like a paperclip) a few times to harden it. That, too, helps the ring stay closed.

To make chainmaille jewelry, I buy either dead soft or half-hard wire, but dead soft wire is better for my purposes.

Half-Hard Wire

The problem with half-hard wire is that it tends to spring back into its original shape. The act of coiling the wire to make jump rings will make the silver wire even harder. When I make a coil of wire to cut into jump rings, the coil will unwind somewhat so that the resulting rings have a larger inside diameter than I want. This is called “spring back.” For example, if I’m coiling the wire around a 3.5 mm mandrel, the final rings might have an inner diameter of 3.6 or 3.7 mm. This might not seem like a lot, but the chain will be looser, less dense, than desired. For some weaves, just as JPL, that little bit of spring back can ruin the chain.

Finally, when you weave the jump rings into the chain and try to close them, they will tend to re-open. To fix this, you have to over-twist the rings, past the place where the ends meet up, and let them spring back into the correct place. As a result, it can be quite a challenge to get the rings to close exactly.

Dead Soft Wire

Dead soft wire is better for making wire coils because you won’t have as much of a spring back problem. For example, if you wind the wire around a 3.5 mm mandrel, your jump rings will have a 3.5mm inner diameter, exactly what you want. During the process of making wire coils to cut into rings, the wire will harden up slightly, but not enough to cause any significant spring back.

The rings will also be much easier to close perfectly when making a chain. You will have a lot more control over the rings.

On the other hand, the rings will be soft. If the chain gets any stress, such as being yanked or smashed, the rings will be likely to open up. What you want is to make the chain with soft wire and then to make the wire as hard as possible after the chain is done.

Soft Wire and Hard Jewelry

Soft wire is easier to use, but hard wire keeps its shape. This means the chainmaille jeweler needs to find a way to weave with soft wire and turn it into hard wire in finished chains.

As mentioned, coiling the wire makes it a little harder. Opening and closing the jump rings also makes the wire harder (just like a paperclip), as does bending the ring back a forth a few times while closing it. Although this helps, it might not make the wire hard enough to keep the rings closed and the chain beautiful. This is where the tumbler becomes so important.

I polish silver chain in my tumbler. During that time in the tumbler, the silver rings are hammered countless times by the steel shot. Not only will they be beautifully polished but also the wire rings will be much harder—in their finished shape! Longer tumbling times will produce even harder wire.

But this, too, can cause a problem. What if, after tumbling the chain, you find that some of the ring closures are not perfect? Perhaps the wire had just enough hardness that the jump rings slowly opened a little so the cut ends don’t perfectly match up? If the wire is too hard, the closures will be hard to correct. To solve this, I will tumble silver chain twice. The first time, I will tumble them for about half an hour, and then I take them out and inspect them carefully. If necessary, I fix any closures. Then, I put tumble the chain again for at least an hour.

Once that’s done, I have a beautiful silver chain that will keep its shape and last for years.

Other Uses

People who make earring wires also have the same problem with wire hardness, maybe a worse problem because the wire gauge is generally smaller than used in chainmaille and the wire hoop is pretty big by comparison to jump rings.

For earring wires, you will want to use half-hard wire to start with, and then to harden it further once the earring wires are shaped. Many people hammer the wire, but that changes their appearance. Here, again, tumbling the earring wires will solve the problem.

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