String (music)

In music, strings are long flexible structures on string instruments that produce sound through vibration. Strings are held under tension so that they can vibrate freely. The pitch (frequency) at which a string will vibrate depends on its length, tension, and thickness.

There are two main kinds of strings: plain and wound. Plain strings are made from a single piece of material, often nylon, gut, or steel. Wound strings have a central core with other material tightly wrapped around them.

Before World War II, many instruments like violins, lutes, and guitars used strings made from a material called catgut, which came from animal intestines. Later, steel and nylon became popular because they could produce different sounds. Wound strings, especially those made of steel, allowed instruments to play lower notes with thinner strings.

This change helped instrument makers create thinner strings for low notes on instruments like the double bass, making them easier to play. For instruments like the piano that use a keyboard to strike the strings, wound strings allowed builders to make smaller upright pianos that could still play deep bass notes.

String construction

The end of a string that attaches to a tuning mechanism on a musical instrument is usually plain. The other end can be plain, loop-shaped, or have a small ball, depending on the instrument. For guitars, this end helps keep the string fixed in place, while for violin family instruments, it keeps the string secure at the other end.

Strings can be made in different ways. Some have a round wire wrapped around a core, which is simple and inexpensive but can cause squeaking sounds and wear on the instrument. Others have a flat wire wrapped around a core, which is more comfortable to play and reduces wear but can be more expensive and harder to bend. There are also strings that combine features of both round and flat types, offering a balance of comfort and sound. The core of the string can be either hexagonal or round, each offering different benefits in stability and flexibility.

Gauge

The thickness of a string, called its gauge, affects how it sounds and feels. Thicker strings are heavier and need more pressure to press down on the fingerboard, while thinner strings are easier to press but may not stay in tune as well. For guitars, sets of strings often come in specific thicknesses, measured in thousandths of an inch. Electric guitars usually have thinner strings than acoustic guitars, which need thicker strings to project sound without amplification. Bass guitars also come with different thicknesses depending on their size.

Bowed strings

Since the 20th century, string makers have often sold strings for bowed instruments by how tight they are, not by their size. They usually offer three levels: heavy, medium, and light. However, these levels can vary between brands, so one company's medium string might feel different from another's. Before 1900, strings were also sold in similar ways.

Some modern strings with a gut core and metal winding are sold by specific size measurements. A system called the Pirazzi meter, where one unit equals 0.05 mm, is used by some companies. For example, a string measured as 14 1/2 PM would be 0.725 mm wide. Some string brands still use the old heavy, medium, or light labels, while others use exact measurements in mm or the PM system.

Core materials

Steel is the main material used for most metal strings. Some instruments, like the harpsichord and Gaelic harp, use brass. Other materials such as silk, gut, or synthetics like nylon and kevlar are also used. Steel strings are often hardened and tempered for better sound.

Steel strings are popular for electric guitars and basses because they produce a bright tone. Nylon strings, used for classical music, have a softer, mellow sound and need less tension, making them good for older guitars. Gut strings, made from animal intestines, were used in ancient times and are still favored by some musicians today for their special sound.

Winding materials

Aluminum, silver, and chrome steel are often used for violin and viola strings, while acoustic guitar strings are usually made with bronze, and piano strings with copper. To prevent damage from sweat, aluminum can be used in a special mix called hydronalium. Classical guitar strings are typically made from nylon. Electric guitar strings are usually covered with nickel-plated steel, and sometimes pure nickel or stainless steel is used. Bass guitar strings are most commonly made with stainless steel or nickel. Copper, gold, silver, and tungsten are used for some special instruments. Silver and gold are costlier and help prevent damage and irritation.

Some older-style strings have an open metal design that looks like a "barber pole". This style helps improve the sound of thicker gut strings by adding weight while keeping the string thin for its tightness. Examples of these open-wound strings date back to the early 1700s from items made by Antonio Stradivari. "Silk and steel" guitar strings are steel strings with thin silk threads underneath the winding.

Phosphor bronze was created by D'Addario in the early 1970s. Phosphor bronze is said to keep its bright sound longer than other strings. Small amounts of phosphorus and zinc are added to the bronze to help it resist damage.

80/20 bronze strings are made from 80 percent copper and 20 percent zinc. The zinc gives these strings a brighter sound, extra strength, and helps them stay good longer. With a special coating, they stay even better. However, if the coating isn’t done well, the strings can lose their sound quickly and may change color in damp conditions because of the copper. The name “80/20 bronze” isn’t quite right since bronze is actually a mix of copper and tin; these strings are more correctly called brass.

Some acoustic guitar players use strings made with nickel-plated steel, originally designed for electric guitars. These nickel-plated strings work well for acoustic guitars with certain types of pickups.

Main article: String construction

String corrosion and prevention

Metal strings can get damaged over time because of a process called oxidation and corrosion. Metals like brass and bronze, which are often used in string windings, are especially prone to this. Oils and moisture from a player's fingers can speed up this damage. In steel strings, oxygen in the air reacts with iron to create rust, which makes the strings sound dull.

To protect strings, some are coated with special materials like polymer or plated with metals such as tin, nickel, gold, or silver. These coatings help keep the strings sounding good longer. Certain polymers, like Teflon, are very effective because they resist many harmful substances and keep the strings smooth and easy to play.

Some musicians boil their guitar or bass strings to clean them. Boiling helps remove oils, salts, and dirt that build up from playing. It can also loosen tiny metal pieces that get stuck in the strings, making them sound better again. However, boiling can sometimes make the strings a bit less flexible.

String vibration

Main articles: Mersenne's laws and Vibrating string

When a string is plucked or strummed, it vibrates in a special way. The main sound we hear is called the fundamental frequency, and it depends on how thick the string is, how long it is, and how tightly it is stretched. This frequency decides the pitch of the note. Along with the main pitch, we also hear other sounds called overtones. These are higher sounds that get quieter as they go higher. For example, if the main pitch is 440 Hz (the note A above middle C), the overtones might be at 880 Hz, 1320 Hz, and so on.

Sometimes a string can start vibrating on its own when other sounds around it match its natural frequency. This is called sympathetic vibration. In some music, like with electric guitars, musicians sometimes let the guitar make a loud, howling sound called feedback. This happens when the guitar is close to a loud speaker, and it can create cool effects in certain kinds of music.

Tensile properties

When you tune a stringed instrument, you put a lot of pressure on the strings. This pressure is called stress. The stretch or lengthening of the string is called strain. As you tune the string to a higher note, it becomes longer and thinner.

If a string is stretched too far, it won’t return to its normal shape and can’t be tuned properly. Musicians want their strings to stay in the elastic region, where they can return to their original shape after being stretched. This keeps the instrument playing well.