What Are Guitar Strings Made Of? (Materials Guide)

The Anatomy of a Guitar String

A guitar string has two parts: the core wire in the middle and the winding wrapped around it. The three wound strings (low E, A, D) on a light-gauge acoustic set use a core wire roughly .014" to .020" thick and a winding wire about .005" to .009" thick. The three plain strings (G, B, high E) on the same set are just a bare core wire with no winding, ranging from .010" to .024" thick. This basic construction has been standard since the 1930s, though the materials have evolved significantly.

The core wire is almost always steel, typically a high-carbon steel drawn and heat-treated for tensile strength. The winding is where the real material variation happens, and it is also where most of the tonal character comes from. I have tested dozens of string sets at the Strum Avenue bench over the years, and the winding material makes the biggest audible difference between otherwise identical sets.

Phosphor Bronze: The Modern Acoustic Standard

Phosphor bronze is an alloy of roughly 92% copper, 7.7% tin, and 0.3% phosphorus. It was introduced by D'Addario in 1974 and has become the dominant winding material for acoustic guitar strings. Phosphor bronze produces a warm, complex tone with good bass response and a slightly subdued high end, which matches the sonic ideal most acoustic players want. D'Addario EJ16 Phosphor Bronze Light ($7/set) is the best-selling acoustic string in the world and has been for over 20 years.

The phosphorus content is what separates phosphor bronze from plain bronze. Phosphorus prevents the copper from oxidizing as quickly, so phosphor bronze strings hold their tone about 30-50% longer than plain 80/20 bronze. Most players can feel the difference after about 10-20 hours of playing: 80/20 bronze starts to sound dull faster, while phosphor bronze stays musical for 40-60 hours.

80/20 Bronze: The Bright Alternative

80/20 bronze strings are 80% copper and 20% zinc, technically brass rather than bronze, despite the name. This alloy was the standard acoustic string winding from the 1930s through the early 1980s, and many players still prefer it for its bright, open tone. Martin SP 80/20 Bronze ($7/set) and D'Addario EJ10 80/20 Light ($7/set) are the two most popular options today.

The main downside of 80/20 bronze is its short lifespan. Without the phosphorus that prevents oxidation, 80/20 strings can lose their brightness within 5-15 hours of active playing. Bluegrass flatpickers who record frequently often change 80/20 strings before each session to keep the tone consistent. For weekend players who want maximum brightness and don't mind changing strings more often, 80/20 is the right choice.

Coated Strings: Elixir and the Imitators

Coated strings are standard wound strings with a thin polymer coating applied over the winding. W.L. Gore introduced the technology under the Elixir brand in 1997, and the original Nanoweb and Polyweb coatings extended playable string life from 40-60 hours to 150-250 hours. The trade-off was a slightly duller initial tone and a 3-4x higher price (roughly $18/set vs. $7/set for uncoated phosphor bronze).

Modern coated strings have narrowed the tonal gap. Elixir Phosphor Bronze Nanoweb ($18/set) now sounds only slightly duller than uncoated phosphor bronze in controlled tests, and the string life is genuinely 3-4x longer. D'Addario XT ($15/set) and Martin Lifespan 2.0 ($12/set) are competing coated options. For players who sweat heavily or play outdoors, coated strings are worth the extra money. For pristine-tone obsessed recording players, uncoated strings still win.

Electric Guitar String Materials (Briefly)

Electric guitar strings use different materials because they work with magnetic pickups, which only sense ferromagnetic metals. The winding is usually nickel-plated steel (most common, bright tone) or pure nickel (warmer, more vintage character). Pure nickel was the original electric string material from the 1950s, and many players who seek a pre-1965 vintage tone still prefer it. Ernie Ball Slinky nickel-plated steel ($6/set) and Dunlop Pure Nickel ($8/set) are the two most common options.

Stainless steel electric strings offer a bright, aggressive tone that resists sweat and corrosion. D'Addario EXL110 XL Nickel Wound is 90% of the electric market; stainless steel sets like the D'Addario EXL110 Stainless ($8/set) are less common but preferred by players who want maximum brightness and longer string life.

How to Choose Strings for Your Guitar

Start with phosphor bronze in a light gauge (.012-.053) for most acoustic guitars. This is the default that 80% of acoustic players settle on long-term. D'Addario EJ16, Martin MA540, and Elixir Nanoweb Phosphor Bronze Light are all safe choices that will sound good on almost any decent guitar.

Switch to 80/20 bronze if you want a brighter, more open tone and don't mind changing strings more often. Switch to coated strings if you play outdoors, sweat heavily, or change strings less than once a month. Experiment with gauge (going up to medium .013-.056 or down to extra-light .010-.047) only after you have settled on a winding material you like. Gauge changes affect playability and intonation, so plan to set up the guitar if you move between gauges permanently.

Avoid very cheap no-name strings. A $3/set bargain string often fails within 5-10 hours and can break unexpectedly. The marginal cost of $4-5 to upgrade to a proper brand is negligible compared to the cost of a broken string during a performance.