Foundations

Woods, Metals and Skins: Materials in Musical Instruments

Spruce, ebony, brass, gut, steel and animal skin each solve a different acoustic or mechanical problem, and the choice among them is increasingly shaped by law and supply.

Every instrument is a set of decisions about matter: what vibrates, what bears tension, and what survives years of handling. This article surveys what woods, metals, strings and membranes commonly contribute, why makers favour certain combinations, how international trade rules now affect some tonewoods and other materials, and why alternatives are being tested and adopted.

Matter that has to work

A musical instrument is, among other things, a collection of decisions about matter. Something must vibrate, something must hold tension, something must survive years of handling, and each job favours different properties: stiffness, lightness, damping, hardness, resistance to moisture. Makers in every tradition have answered these questions with materials that were locally available and workable, then refined the answers over generations. What an instrument is made of is therefore partly an acoustic choice and partly a record of forests, trade routes, workshops and, more recently, regulation.

No single property explains a sound. Shape, thickness, varnish, strings and the player’s technique all interact with the material, and makers and researchers still disagree about how much any one ingredient contributes. Statements that a particular wood or alloy has a fixed sonic character are best read as tendencies rather than rules. What follows describes what materials commonly do and why they keep being chosen.

Spruce and maple: light tops, dense backs

Across the bowed and plucked string families the same pairing recurs. The top plate receives vibration from the strings and moves the surrounding air, so it needs to be light for its stiffness. Spruce, a softwood that splits cleanly along straight grain, meets that need, and it is the usual top of a Violin, Viola and Cello. The back and ribs of those instruments are commonly maple, a denser hardwood that reflects and shapes the vibration rather than simply radiating it. A Piano follows a related logic, with a spruce soundboard behind the strings, while many acoustic guitar makers use spruce or cedar for the top and a range of hardwoods for the back and sides.

How the tree grew matters as much as its species. Makers traditionally prefer softwood with narrow, even growth rings for soundboards, and they season the timber for years so that it stops shrinking before it is carved. Even then a finished plate is never inert. It keeps trading moisture with the surrounding air, which is why wooden instruments react to climate and why their care is a topic of its own.

Ebony, blackwood and other hard surfaces

Where a part is rubbed, pressed or struck, makers reach for density. Ebony, a very hard, dark wood, is the traditional choice for the fingerboards of the violin family because it resists the wear of strings and fingertips. Pegs and tailpieces are often made from ebony or from other dense hardwoods such as rosewood and boxwood.

Woodwinds show the same preference in a different form. The Oboe is made from grenadilla, also called African blackwood, and the Clarinet is frequently made from it as well. A dense wood holds the crisp edges of the tone holes, tolerates the moisture of the player’s breath better than softer timber, and keeps a bore of precise dimensions. The Bassoon is traditionally made of maple. Wood is not the only option for winds: many instruments intended for learners are made from resin or composite materials, which resist cracking and need less attention.

Brass, silver and nickel

Brass is an alloy of copper and zinc, and its combination of workability and strength makes it the metal of the Trumpet, Trombone, French horn and Tuba. Sheet is hammered, spun and soldered into tubing and flared bells. Makers vary the proportions of copper and zinc, and they finish the surface with lacquer or plating. Whether the alloy itself changes the tone is debated; most players and makers agree that the shape of the bore and bell, the mouthpiece and the player have larger effects.

Nickel silver, despite its name, contains no silver. It is an alloy of copper, nickel and zinc that is stiff, machines well and accepts plating, which is why it is widely used for keywork, slides and the bodies of many flutes. Flutes are also made of sterling silver and, at the upper end, gold, and makers and players continue to debate what the metal adds beyond the wall thickness and design. Copper, for its part, is the traditional shell material of Timpani, according to the Philharmonia Orchestra, which also notes that fibreglass is a contemporary alternative.

Gut, steel and nylon

Strings solve a separate problem: they must be strong, uniform and elastic, and they must hold pitch under heavy tension. For centuries the answer was gut, made from the intestines of sheep and some other animals. Gut strings have a warm sound and respond readily to changes in humidity. Steel wire became the standard for pianos and, in time, for many guitar strings and many violin-family strings because it is strong, bright and stable at high tension. The electric guitar depends on it, since magnetic pickups respond only to strings that contain magnetic metal.

Bass strings present a further difficulty, because a thick string that is heavy enough to sound low is often too stiff to vibrate well. Makers therefore wrap a core with fine metal wire, such as copper or silver, to add mass without adding stiffness. Nylon and other synthetics arrived in the twentieth century as stable alternatives to gut and are now common on classical guitars and, as cores, on many bowed strings. The Harp shows the layering clearly: according to the Philharmonia Orchestra, its lowest strings are steel, most of the rest are gut, and some players use nylon for the highest notes because gut there tends to break.

Skins and heads

A drum’s vibrating surface must be thin, even and able to hold tension, and animal skin met those requirements long before any synthetic film existed. Calfskin remains the traditional head of the timpani, as the Philharmonia Orchestra notes, and goat and other skins are used on many hand drums and on the traditional Banjo. Skin responds to weather: it tightens in dry air and slackens in damp air, so the pitch and feel of a skin-headed drum can shift through a single day.

Synthetic heads, made from polyester film, began to spread through the mid-twentieth century and are now the normal choice on the drum kit. They are far less sensitive to humidity, last longer and are consistent from one head to the next. Many percussionists and banjo players still prefer skin for its feel and tone, and both materials are in active use. The choice is often made by repertoire, by climate and by how much adjustment a player is willing to do.

Protected species and changing choices

Some of the most prized instrument materials come from slow-growing or heavily harvested species, and international trade in several of them is regulated under CITES, the convention that controls cross-border trade in listed plants and animals. Brazilian rosewood, Dalbergia nigra, has been under the strictest level of control for decades. Other rosewood species were added in the 2010s, and the rules that apply to finished instruments have been revised since then to reduce the burden on travelling musicians. Pernambuco, the traditional wood of bows for the violin family, is listed in Appendix II, and the U.S. Fish and Wildlife Service reports that an amended listing that took effect in March 2026 exempts finished instruments and bows in non-commercial trade, for purposes such as performance, teaching and repair. Old ivory keys and fittings can also require documentation; the agency states that African elephant ivory removed from the wild after early 1977 does not qualify as pre-Convention material.

These rules are technical, they differ between species and countries, and they change, so anyone buying, selling or crossing a border with an instrument should check the current position with the relevant national authority. The pressure has nevertheless changed practice. Makers document where timber comes from, test laminated or thermally treated woods, and adopt alternative species and composites such as carbon fibre. Whether these substitutes match the traditional materials is a matter of continuing argument, but the range of acceptable materials is widening.

Terms used in this article

CITES: The Convention on International Trade in Endangered Species of Wild Fauna and Flora, an agreement that regulates cross-border trade in listed species and their products.
grenadilla: A very dense, dark tropical wood, also called African blackwood, used for oboes and many clarinets.
nickel silver: An alloy of copper, nickel and zinc that contains no silver, valued for stiffness and for accepting plating.
pre-Convention: A term for material acquired before a species was listed by CITES, which may be eligible for different documentation rules.
soundboard: A thin wooden panel that vibrates with the strings and moves more air than the strings could alone.
tonewood: Timber selected for its acoustic properties, such as stiffness, density and straight grain, and used for soundboards, backs and other sounding parts.
wound string: A string whose core is wrapped in fine wire to add mass and lower the pitch without making the string too stiff.