String (music)

There are several varieties of wound strings available.

The simplest wound strings are roundwound—with round wire wrapped in a tight spiral around either a round or hexagonal core. Such strings are usually simple to manufacture and the least expensive. They have several drawbacks, however:

• Roundwound strings have a bumpy surface profile (the bumps of the winding) that produce friction on the player's fingertips. This causes squeaking sounds when the player's fingers slide over the strings, especially when used on electric guitar with a guitar amplifier or with an acoustic guitar amplified through a PA system. (Some artists use this sound creatively, such as hardcore punk and heavy metal music electric guitarists who scrape the pick down the lower-pitched strings for an effect.)
• Roundwound strings' higher friction surface profile may hasten fingerboard and fret wear, compared with smoother flatwound strings.
• When the core is round, the winding is less secure and may rotate freely around the core, especially if the winding is damaged after use.
  

Flatwound strings also have either a round or hex core. However, the winding wire has a rounded square cross-section that has a shallower profile (in cross-section) when tightly wound. This makes for more comfortable playing, and decreased wear for frets and fretboards (this makes them a popular choice for fretless instruments). Squeaking sounds due to fingers sliding along the strings are also decreased significantly. Flatwound strings also have a longer playable life because of smaller grooves for dirt and oil to build up in.

On the other hand, flatwound strings sound less bright than roundwounds and tend to be harder to bend. Flatwounds also usually cost more than roundwounds because of less demand, less production, and higher overhead costs. Manufacturing is also more difficult, as precise alignment of the flat sides of the winding must be maintained (some rotation of the winding on roundwound strings is acceptable).[1][2]

Modern bowed strings are plain (typically the higher-pitched, thinner strings) or flatwound, to allow smooth playing and reduce bow hair breakage. There is a niche market for roundwound fiddle strings.

Halfround (also referred to as halfwound, ground wound, or pressure wound strings) are a cross between roundwound and flatwound. Such strings are usually made by winding round wire around a round or hex core first, then polishing, grinding (thus the name, ground wound) or pressing the exterior part of the winding until it is practically flat. This results in the flat, comfortable playing feel of flatwounds, along with less squeaking, with a brightness generally between roundwounds and flatwounds. The polishing process removes almost half of the winding wire's mass; thus, to compensate for it, manufacturers use winding wire of a heavier gauge. Because of the extra manufacturing process involved, they are normally more expensive than roundwounds, but less than flatwounds.

There are two types, or shapes, of core wire typically used in wound strings.

Hexcore strings are composed of hexagonal core wire and a tight (usually round) winding. Hexcore string design prevents the winding from slipping around the core – which can occur with round core strings. This may improve tuning stability, flexibility, and reduce string breakage, compared to round core strings.[3]

Round core strings are composed of regular round core and a tight (usually round) winding. Round core is the traditional "vintage" way of manufacturing and results in a greater contact between the winding and the core of the string.

Steel strings for six-string guitar usually come in sets of matched strings. Sets are usually referenced either by the gauge of the first string (e.g., 9), or by pair of first and last (e.g., 9–42); measurements in thousands of an inch are the de facto standard, regardless of whether Imperial units are used in a country. Some manufacturers may have slightly different gauge sequences; the sample data below comes from D'Addario string charts for regular, round-wound, nickel-plated strings.

The following table displays the gauges in inches: (Note: strings in dark gray boxes are wound. All others are plain.)

The following table displays the gauges in millimeters:

String gauge is subject to the personal preferences of the musician, but acoustic guitars are typically strung with a heavier gauge than electric guitars. The need for projection due to lack of amplification is one of the main reasons for this.[4] (Note: strings in dark gray boxes are bronze wound. All others are plain. These are for steel-string guitars, not classical nylon/gut strings. The gauge values are in inches.)

Bass guitar strings are sometimes made for a particular scale length and come in short, medium, long and extra long (sometimes called super long) scale. Almost all bass guitar strings are made wound. Typical bass guitar strings come in the following gauges:

Steel or metal strings have become the foundation of strings for the electric guitar and bass. They have a pleasingly bright tone when compared to nylon strung guitars. Their metal composition varies greatly, sometimes using many different alloys as plating. Much of the history of metal strings evolved through innovations with the piano. In fact, the first wound metal strings ever used were used in a piano. However, when it came to getting super small diameter strings with good elastic properties, the electric guitar took the metal string to the next level adapting it for the use of pickups.

Because of the higher tension of steel strings, steel-strung guitars are more robustly made than 'classical' guitars, which use synthetic strings. Most jazz and folk string players prefer steel-core strings for their faster response, low cost, and tuning stability.[5]

Nylon string,[6] traditionally used for classical music, has a more mellow tone, and the responsiveness of it can be enjoyed typically for folk but other styles of music use it as well (for example, Willie Nelson performs on a nylon strung guitar). Nylon strings are made of a softer, less dense material and are under less tension than steel strings (about 50% less). This means they can be used on older guitars that can't support the tension of modern steel strings.

Nylon strings do not work with magnetic pickups, which require ferrous strings that can interact with the magnetic field of the pickups to produce a signal.

Currently, stranded nylon is one of the most popular materials for the cores of violin, viola, cello, and double bass strings. It is often sold under the trade name of Perlon. Nylon guitar strings were first developed by Albert Augustine Strings in 1947.[7]

The intestine, or gut, of sheep, cattle, and other animals (sometimes called catgut, though cats were never used as a source for this material) is one of the first materials used to make musical strings.[8] In fact, the Ancient Greek word for string, "khordḗ," has "gut" as its original meaning.

Animal intestines are composed largely of elastomers, making them very flexible. But they are also extremely hygroscopic, which makes them susceptible to pitch fluctuation as a result of changing humidity. Exposure to moisture from the sweat of a musician's hands can cause plain (unwound) gut strings to fray and eventually break. This is not as much of a problem with wound gut strings, in which the gut core, being protected from contact with perspiration by the metal winding (and underlayer, if there is one), lasts a much longer time. Nonetheless, as such a gut string ages and continually responds to cyclic changes in temperature and humidity, the core becomes weak and brittle, and eventually breaks. Furthermore, all gut strings are vulnerable to going out of tune due to changes in atmospheric humidity.

However, even after the introduction of metal and synthetic core materials, many musicians still prefer to use gut strings, believing that they provide a superior tone. Players associated with the period performance movement use wound and unwound gut strings as part of an effort to recreate the sound of music of the Classical, Baroque, and Renaissance periods, as listeners would have heard it at the time of composition.

For players of plucked instruments, Nylgut strings are a recently developed alternative to gut strings. They are made from a specialty nylon and purport to offer the same acoustic properties as gut strings without the tuning problems.

Fluoropolymer strings are available for classical guitar, harp, and ukulele. These strings are usually traded under descriptions like fluorocarbon, carbon fiber, or carbon, which is scientifically incorrect.

The so-called Carbon material has a higher density than nylon, so that a nylon string can be replaced by a carbon string of smaller diameter. This improves the precision of higher fretted notes, and the resulting vibrational behaviour leads to a more brilliant sound with improved harmonics. In particular, classical guitarists who feel that a nylon G string sounds too dull can use strings that include a carbon G string.[9]

Other polymers, including polyetheretherketone and polybutylene terephthalate, have also been used.[10][11]

Silk was extensively used in China for traditional Chinese musical instruments until replaced by metal and nylon strings in the 1950s. Only purely silk strings used for the guqin are still produced, while some silver-wound silk strings are still available for classical guitars and ukuleles. The quality in ancient times was high enough that one brand was praised as 'ice strings' for their smoothness and translucent appearance.[12]

Phosphor bronze was introduced by D'Addario in the early 1970s. Phosphor bronze is said to keep its "new" sound longer than other strings. Small amounts of phosphorus and zinc are added to the bronze mixture. This makes the phosphor bronze slightly more corrosion resistant than 80/20 bronze.

80/20 bronze strings are 80 percent copper and 20 percent zinc.[13] The zinc also gives it a brighter tone, additional hardness and slows down the aging process. With additional string coating, they are preserved even more. Although, If some of the coating is applied poorly, the strings can lose their tone in just a matter of hours, and if left in high humidity can turn a hint of green because of the copper and corrode with time. The name "80/20 Bronze" is a misnomer since bronze is by definition an alloy of copper and tin. "80/20 bronze" strings would be more correctly referred to as brass.[14]

Some acoustic players use strings, wound with nickel-plated-steel, meant for electric guitar. The properties of the nickel-plated strings make it a good choice for flattop guitars with sound hole-mounted magnetic pickups.

Some common types of metal plating on strings include tin, nickel, gold, and silver. Some metals such as gold and silver give the strings a different sound. Among strings coated with a polymer, (polytetrafluoroethylene) Teflon is the most commonly used. Teflon is resistant to many corrosive agents such as: chlorine, acetic acid, sulfuric acid, and hydrochloric acid. On the microscopic level Teflon has very tightly packed polymeric chains, and these tightly packed chains create a slippery surface that not only helps keep the oil from the player's hands off the strings but makes them smooth to play as well.[18] Ethylene tetrafluorothylene (ETFE) is another polymer that is sometimes used to coat strings. It is abrasion and cut resistant and has many characteristics similar to Teflon.[19]

Some musicians boil guitar or bass strings to rejuvenate them. The high temperature of the boiling water helps free the strings of oil, salt, and grime from the player's hands. When a string is played, very small metal shavings from fret wear may break off and lodge between the windings of the strings. Heating the strings can expand these particles and separate them from the windings. Some players use deionized water to boil strings, believing that mineral deposits in tap water may aid corrosion of the string core. After boiling, strings may have less elasticity and be more brittle, depending on the quality of the alloys involved. Putting the strings through a cycle in the dishwasher has also been known to work.[20]