For most string instrument inventions you might dream up, it’s not too hard find suitable strings. You can usually turn to readily available strings made for one or another standard instrument. Sometimes, though, there’s something about your instrument that makes it unsuitable for standard strings – and then what do you do?
For Steel Strings
The most common string material for musical instruments is steel, and so we’ll start with that. Most steel strings are made from the steel wire known as “music wire,” a term widely used in industry even when the wire is being used for non-musical purposes. Music wire is wire of spring-tempered steel, and it’s favored for musical strings for a couple of reasons. First, it’s got terrific tensile strength and will hold up to tensions that would make other wire materials snap. Second, being an extremely hard metal, it has less internal damping than other alternatives. This allows for greater sustain and it fosters a bright sound due to good support for the high harmonics. One might think that there would be special alloys for musical instrument strings, but no: whether the wire you’re using is sold as guitar strings, banjo strings, piano wire, or music wire for other industrial purposes, the wire itself is all pretty much the same. For musical purposes it’s important that the wire is made to very close tolerances and free of dimensional variation or irregularities, and indeed it generally is.
Plain music wire – that is, wire that is not overwound – is widely available in a finely graduated range of diameters. Whatever length you may need, even if it’s crazy-long, you can get it simply by purchasing raw music wire, which is available in coils of great length. Alternatively, if the length you need isn’t too great, you can get music wire strings ready-made for one or another standard instrument and appropriate them for whatever other oddball instrument you have in mind. Guitar strings are good because they’re inexpensive and widely available. A guitar string out of the package is typically between 38″ and 42″, which translates to a maximum active string lengths for your instrument of a little over 30″ if the bridges and attachments at the ends are configured to maximize playable length.
The thinnest music wire commonly available is .006″, designated as music wire gauge 0000. For musical instruments the useful part of this range starts at about .009″, designated as gauge 0. Strings that are thinner than that will break too easily under tension in most applications. The thickest music wire commonly available without overwinding is .049″ (gauge 22) but it’s unlikely you’d ever want something that thick. Plain wire strings that are too thick will suffer from inharmonicity (detuned overtones) due to their stiffness, and may also be difficult to play for instruments with fingerboards. So for lower notes, where you need the mass of thicker strings, you’ll be looking at overwound strings instead of plain wire. Let’s look at them now.
If the overwound string length you need is not great, you can once again turn to overwound strings made for standard instruments like guitar. If you need overwound strings longer than guitar strings, there are strings for electric bass which may be sold at between 48″ and 53″. And there are overwound piano strings (admittedly rather expensive) up to about 60″. But both of these are available only in heavy gauges. What if you need an overwound string that is long like a bass or piano string but not as thick? Are there other instruments with longer overwound strings, yet which are thin? Unfortunately, not really. Among standard instruments, the longest overwound strings in thin gauges I’ve found are tenor banjo strings at around 42″, which is not much longer than guitar strings.
So what to do if you need a long but not thick overwound string? For that you’ll probably need to have a string custom made. Perhaps you can get one of the leading string manufacturers to do this for you, but more likely in this case you’ll be looking to a special order from a small, artisanal string maker – someone who has a string winding machine capable of producing a string in your sought-after thickness and length. I’ve gone this route on a couple of occasions, working with a company in Los Angeles called Guadalupe Custom Strings. I had feared that custom strings would be terribly costly, but it wasn’t bad, and the quality was good. (Admittedly the turnaround time was a bit slow.)
Here’s one more trick to consider if you need thicker steel strings in lengths and diameters that would be unavailable in overwound wire. This is a way to get a bit more flexibility (and thus less inharmonicity) in a heavier wire. The trick is to use multistrand wire. A cord made up of many strands of thinner wire braided or twisted together is not as flexible as overwound wire of comparable thickness, but it is more flexible than solid wire, and so will be easier to play and less prone to inharmonicity than comparable solid wire. Google AI tells me that stranded music wire is not available over the counter but that you can have it custom made to your specifications by some suppliers. It might be possible to fabricate it yourself: start with several strands of very thin music wire and twist them together to form a single larger cord. Alternatively, you can get readymade stranded wire of other types of steel with various strand-counts and thicknesses. (Be aware that certain common alloys of stainless steel such as the grades designated as 304 and 316 are non-magnetic and will not work with a magnetic pickup.) In larger diameters the lesser tensile strength of these steels will be less of an issue than it would be with thinner cords. I have not explored these possibilities myself; if you try them, let me know how it works out.
Strings of metals other than steel
Historically some instruments have had strings of metals other than steel, typically brasses or bronzes. In thinner gauges these cannot be used at very high tension, but they do OK in the thicker gauges you’d use for lower notes. Their tone quality is a bit warmer than that of music wire – that is to say, less bright. Wires of these materials aren’t always available in the finely graduated range of thicknesses that music wire is, so you might have difficulty finding a wire in just the right thickness.
Nylon strings
For a sound that is rounder and less bright than metal, or for a lighter playiing action, you might be interested in nylon strings. Nylon is lighter in weight than steel and still quite strong. Nylon strings are widely available for classical guitar and ukulele, and you can borrow those strings for other instruments as long as you don’t require unusually long lengths. The material used in these strings is similar to that used for monofilament nylon cord made for other purposes (think of fishing line). However, nylon strings made as musical strings are preferable, at least in principle, because slight dimensional irregularity in typical nylon line might lead to inharmonicity, whereas the made-for-music strings are made to close specifications to be perfectly round and uniform in diameter.
And what if you want longer nylon strings? With just a bit of compromise, you can use widely available monofilament line made for fishing or other purposes. It’s available up to about 0.044″. You can find still larger diameters in weedwacker line. But for such thicknesses, you’d be more likely to turn to a stranded nylon cord, many varieties of which are widely available, for a thick but more flexible nylon string.
Gut
When I was a kid, tennis rackets were still strung in gut, and I even think I vaguely remember seeing some old guitars still strung with gut. The widely used term “catgut” is misleading; sheep or goat intestine has been most commonly used. Now tennis rackets and classical guitars are all nylon, but gut strings are still used for some historic instruments, and they remain available from specialty retailers. Gut strings typically sound a little brighter than nylon but considerably less bright than steel. They’re less dependably uniform than strings manufactured of metal or plastic, meaning that inharmonicity or slightly out-of-whack tuning in the higher frets may be an issue. They also tend to go out of tune when humidity changes. Yet gut was a favored stringing material for a thousand years before modern alternatives came along, and an awful lot of good music was made.
Other materials
You can make musical strings out of anything in a cord-like form that has sufficient tensile strength. If you want to try something crazy as a stringing material, have fun! Here are the basics to keep in mind:
The greater the flexibility the better. Stiff materials tend to produce inharmonic overtones and may be harder to play.
Dimensional uniformity is good. Irregularities may result in inharmonicity and out-of-tune fretting.
Tensile strength is good, making breakage less likely. This is especially a concern for very thin strings.
More massive material will drive sound boards more effectively than lighter. But greater mass will call for greater tension to bring the string up to pitch, and if the material doesn’t have high tensile strength that’s a problem.
Soft materials typically have more internal damping, making for less sustain. The most pronounced camping effect is on the higher overtones. This makes a subjectively warmer, less edgy sound. Hard materials support the high overtones better, making a brighter sound.
Elasticity (stretchiness) is usually undesirable, especially in extreme cases. Stretchy strings tend to be less dependable in tuning, and do not drive a soundboard as forcefully as inelastic materials. Extremely elastic materials are often very soft, and they scarcely support the high overtones at all. Normally you wouldn’t want this, but you may find the saturated tone of stretchy strings, consisting almost entirely of fundamental, unique and appealing.
Cross sectional shape: Strings which are round in cross section have several advantages. Most importantly, they have uniform rigidity for all directions of vibration, preventing unwanted dual-pitch effects. They also minimize the effect of unwanted torsional vibration, and they have comfortable playability. That said, you can still have fun with ribbon-shaped strings.