Tone Wood
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Tonewood refers to specific
wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...
varieties used for woodwind or acoustic stringed instruments. The word implies that certain species exhibit qualities that enhance acoustic properties of the instruments, but other properties of the wood such as aesthetics and availability have always been considered in the selection of wood for musical instruments. According to ''Mottola's Cyclopedic Dictionary of Lutherie Terms'', tonewood is:
Wood that is used to make stringed musical instruments. The term is often used to indicate wood species that are suitable for stringed musical instruments and, by exclusion, those that are not. But the list of species generally considered to be tonewoods changes constantly and has changed constantly throughout history.


Varieties of tonewood

As a rough generalization it can be said that stiff-but-light
softwood Scots pine, a typical and well-known softwood Softwood is wood from gymnosperm trees such as conifers. The term is opposed to hardwood, which is the wood from angiosperm trees. The main differences between hardwoods and softwoods is that the sof ...
s (i.e. from coniferous trees) are favored for the soundboards or soundboard-like surface that transmits the vibrations of the strings to the ambient air.
Hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...
s (i.e. from deciduous trees) are favored for the body or framing element of an instrument. Woods used for woodwind instruments include African blackwood, (''
Dalbergia melanoxylon ''Dalbergia melanoxylon'' (African blackwood, grenadilla, or mpingo) in French ''Granadille d'Afrique'' is a flowering plant in the family Fabaceae, native to seasonally dry regions of Africa from Senegal east to Eritrea, to southern regions of ...
''), also known as grenadilla, used in modern clarinets and oboes. Bassoons are usually made of Maple, especially Norway maple (''
Acer platanoides ''Acer platanoides'', commonly known as the Norway maple, is a species of maple native to eastern and central Europe and western Asia, from Spain east to Russia, north to southern Scandinavia and southeast to northern Iran. It was introduced to ...
)''. Wooden flutes, recorders, and baroque and classical period instruments may be made of various hardwoods, such as pear (''
Pyrus Pears are fruits produced and consumed around the world, growing on a tree and harvested in late summer into mid-autumn. The pear tree and shrub are a species of genus ''Pyrus'' , in the family Rosaceae, bearing the pomaceous fruit of the sa ...
'' species), boxwood (''
Buxus ''Buxus'' is a genus of about seventy species in the family Buxaceae. Common names include box and boxwood. The boxes are native to western and southern Europe, southwest, southern and eastern Asia, Africa, Madagascar, northernmost So ...
'' species), or ebony (''
Diospyros ''Diospyros'' is a genus of over 700 species of deciduous and evergreen trees and shrubs. The majority are native to the tropics, with only a few species extending into temperate regions. Individual species valued for their hard, heavy, dark timb ...
'' species).


Softwoods

*
Spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...
s are often used in the soundboards of instruments from the
lute A lute ( or ) is any plucked string instrument with a neck (music), neck and a deep round back enclosing a hollow cavity, usually with a sound hole or opening in the body. It may be either fretted or unfretted. More specifically, the term "lu ...
,
violin The violin, sometimes referred to as a fiddle, is a wooden chordophone, and is the smallest, and thus highest-pitched instrument (soprano) in regular use in the violin family. Smaller violin-type instruments exist, including the violino picc ...
,
oud The oud ( ; , ) is a Middle Eastern short-neck lute-type, pear-shaped, fretless stringed instrument (a chordophone in the Hornbostel–Sachs classification of instruments), usually with 11 strings grouped in six courses, but some models have ...
,
mandolin A mandolin (, ; literally "small mandola") is a Chordophone, stringed musical instrument in the lute family and is generally Plucked string instrument, plucked with a plectrum, pick. It most commonly has four Course (music), courses of doubled St ...
,
guitar The guitar is a stringed musical instrument that is usually fretted (with Fretless guitar, some exceptions) and typically has six or Twelve-string guitar, twelve strings. It is usually held flat against the player's body and played by strumming ...
, and
harpsichord A harpsichord is a musical instrument played by means of a musical keyboard, keyboard. Depressing a key raises its back end within the instrument, which in turn raises a mechanism with a small plectrum made from quill or plastic that plucks one ...
families; as well as the
piano A piano is a keyboard instrument that produces sound when its keys are depressed, activating an Action (music), action mechanism where hammers strike String (music), strings. Modern pianos have a row of 88 black and white keys, tuned to a c ...
. Spruce is particularly suited for this use because of its high stiffness-to-weight ratio. Commonly used varieties are Sitka (or Alaskan) spruce (''
Picea sitchensis ''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to just over tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-l ...
''), Adirondack (or red) spruce (''
Picea rubens ''Picea rubens'', commonly known as red spruce, is a species of spruce native to eastern North America, ranging from eastern Quebec and Nova Scotia, west to the Adirondack Mountains and south through New England along the Appalachians to western ...
''), Engelmann spruce (''
Picea engelmannii ''Picea engelmannii'', with the common names Engelmann spruce, white spruce, mountain spruce, and silver spruce, is a species of spruce native to western North America. It is highly prized for producing distinctive tone wood for acoustic guitars ...
''), and ''
Picea abies ''Picea abies'', the Norway spruce or European spruce, is a species of spruce native to Northern Europe, Northern, Central Europe, Central and Eastern Europe. It has branchlets that typically hang downwards, and the largest cones of any spruce, ...
'' (variously known as Norwegian, German, Alpine, Italian or European spruce). * Cedars have since the 1950s been used in the tops of
flamenco guitars A flamenco guitar is a guitar similar to a classical guitar, but with lower action, thinner tops and less internal bracing. It usually has nylon strings, like the classical guitar, but it generally possesses a livelier, grittier sound compared ...
(
Mediterranean cypress ''Cupressus sempervirens'', the Mediterranean cypress (also known as Italian cypress, Tuscan cypress, Persian cypress, or pencil pine), is a species of cypress native to the eastern Mediterranean region and Iran. While some studies show it ha ...
), classical guitars (
western red cedar ''Thuja plicata'' is a large evergreen coniferous tree in the family Cupressaceae, native to the Pacific Northwest of North America. Its common name is western redcedar in the U.S. or western red cedar in the UK, and it is also called pacific re ...
, not a true cedar), and to a lesser degree in steel string acoustic guitars. Also, genuine
Lebanon cedar ''Cedrus libani'', commonly known as cedar of Lebanon, Lebanon cedar, or Lebanese cedar (), is a species of large evergreen conifer in the genus ''Cedrus'', which belongs to the pine family and is native to the mountains of the Eastern Mediter ...
wood is used today in
Crete Crete ( ; , Modern Greek, Modern: , Ancient Greek, Ancient: ) is the largest and most populous of the Greek islands, the List of islands by area, 88th largest island in the world and the List of islands in the Mediterranean#By area, fifth la ...
, Syria, and Anatolia region for several traditional musical instruments, like
lyre The lyre () (from Greek λύρα and Latin ''lyra)'' is a string instrument, stringed musical instrument that is classified by Hornbostel–Sachs as a member of the History of lute-family instruments, lute family of instruments. In organology, a ...
. *
Yew Yew is a common name given to various species of trees. It is most prominently given to any of various coniferous trees and shrubs in the genus '' Taxus'': * European yew or common yew (''Taxus baccata'') * Pacific yew or western yew ('' Taxus ...
was once widely used for
lute A lute ( or ) is any plucked string instrument with a neck (music), neck and a deep round back enclosing a hollow cavity, usually with a sound hole or opening in the body. It may be either fretted or unfretted. More specifically, the term "lu ...
bowls. * Other softwoods, such as
redwood Sequoioideae, commonly referred to as redwoods, is a subfamily of Pinophyta, coniferous trees within the family (biology), family Cupressaceae, that range in the Northern Hemisphere, northern hemisphere. It includes the List of superlative tree ...
and
Douglas-fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is the tallest tree in the Pinaceae family. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Or ...
have been used to a limited degree. Redwood is not used commonly for guitars with steel strings, but has been used for
classical guitar The classical guitar, also known as Spanish guitar, is a member of the guitar family used in classical music and other styles. An acoustic wooden string (music), string instrument with strings made of catgut, gut or nylon, it is a precursor of the ...
s.


Hardwoods

*
Maple ''Acer'' is a genus of trees and shrubs commonly known as maples. The genus is placed in the soapberry family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated si ...
, especially
Norway Maple ''Acer platanoides'', commonly known as the Norway maple, is a species of maple native to eastern and central Europe and western Asia, from Spain east to Russia, north to southern Scandinavia and southeast to northern Iran. It was introduced to ...
and
Sycamore Maple ''Acer pseudoplatanus'', known as the sycamore in the British Isles and as the sycamore maple in the United States, is a species of maple native to Central Europe and Western Asia. It is a large deciduous, broad-leaved tree, tolerant of wind an ...
, is traditionally used for the backs and sides of violin family instruments.
Bosnian Maple Bosnian maple is a type of ''Acer platanoides'', a European mountain maple indigenous to former Yugoslavia. It was a very high grade of maple, very light and very strong, according to some the best wood in the world for making violins, as it had the ...
is probably the maple used by the Italian violin makers Stradivari and Guarneri. Maple is also frequently seen in acoustic guitars and mandolins. Most Fender electric guitars feature maple necks (it is one of the hardest and most stable tonewoods, so it is often used in the neck because of its ability to withstand high string tension). Hard maple is commonly used for wooden tripods for its vibration damping properties. Variations of maple (commonly maple wood with flamed or
quilted Quilting is the process of joining a minimum of three layers of textile, fabric together either through stitching manually using a Sewing needle, needle and yarn, thread, or mechanically with a sewing machine or specialised longarm quilting ...
grains) are used on the tops of electric guitars for aesthetic purposes. The very sturdy frame of the modern piano is usually made of maple or of
beech Beech (genus ''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to subtropical (accessory forest element) and temperate (as dominant element of Mesophyte, mesophytic forests) Eurasia and North America. There are 14 accepted ...
. *
Mahogany Mahogany is a straight- grained, reddish-brown timber of three tropical hardwood species of the genus ''Swietenia'', indigenous to the AmericasBridgewater, Samuel (2012). ''A Natural History of Belize: Inside the Maya Forest''. Austin: Universit ...
may be used in the tops of some guitars as well as the back, sides, and necks of instruments of the
mandolin A mandolin (, ; literally "small mandola") is a Chordophone, stringed musical instrument in the lute family and is generally Plucked string instrument, plucked with a plectrum, pick. It most commonly has four Course (music), courses of doubled St ...
and
guitar The guitar is a stringed musical instrument that is usually fretted (with Fretless guitar, some exceptions) and typically has six or Twelve-string guitar, twelve strings. It is usually held flat against the player's body and played by strumming ...
families. Mahogany may also be used for the solid bodies of electric guitars, such as the
Gibson Les Paul The Gibson Les Paul is a solid body electric guitar that was first sold by the Gibson Guitar Corporation in 1952. The guitar was designed by factory manager John Huis and his team with input from and endorsement by guitarist Les Paul. Its typic ...
. Due to lack of availability, other similar woods are used as mahogany replacements, such as
Australian red cedar ''Toona ciliata'' is a forest tree in the mahogany family which grows throughout South Asia from Afghanistan to Papua New Guinea and Australia. Names It is commonly known as the red cedar (a name shared by other trees), tone, toon or toona (als ...
, ''
Toona sureni ''Toona sureni'' is a species of tree in the mahogany family. It is native to South Asia, Indochina, Malesia, China, and Papua New Guinea. It is commonly known as the suren toon, surian, limpaga, iron redwood or the red cedar (a name also shared ...
'', African mahogany (Khaya), meranti (Lauan),
Kauri ''Agathis'', commonly known as kauri or dammara, is a genus of evergreen coniferous trees, native to Australasia and Southeast Asia. It is one of three extant genera in the family Araucariaceae, alongside '' Wollemia'' and ''Araucaria'' (being ...
(Agathis),
mora Mora may refer to: People * José Maria Mora (1847–1926), Cuban-American photographer, often credited as "Mora" * Mora (singer) (born 1996), a Puerto Rican singer * Mora (surname), a Spanish name (includes a list of people with the name) Plac ...
(Nato),
sapele ''Entandrophragma cylindricum'' is a tree of the genus ''Entandrophragma'' of the family ''Meliaceae''. It is commonly known as sapele or sapelli ( ) or sapele mahogany, as well as aboudikro, assi, and muyovu. Origin of the name The name ''sape ...
, ''
Entandrophragma utile ''Entandrophragma utile'', called the sipo or utile, is a species of large tree in the genus ''Entandrophragma'', native to nearly all of tropical Africa facing the Atlantic, from Guinea to Angola, and as far east as Uganda. The timber is traded ...
'' (sipo),
nyatoh Nyatoh is a trade name for wood of a number of hardwood species of the genera ''Palaquium'' and ''Payena'' growing in rainforest environments in southeast Asia, especially in Indonesia and the Philippines. Nyatoh wood is reddish and most species ar ...
and okoume. Some of these alternatives are mahogany family timbers. *
Rosewood Rosewood is any of a number of richly hued hardwoods, often brownish with darker veining, but found in other colours. It is hard, tough, strong, and dense. True rosewoods come from trees of the genus '' Dalbergia'', but other woods are often ca ...
s are often used in the back and/or sides of guitars and mandolins and
fretboards The fingerboard (also known as a fretboard on fretted instruments) is an important component of most stringed instruments. It is a thin, long strip of material, usually wood, that is laminated to the front of the neck of an instrument. The strin ...
on guitars. The most sought-after variety, Brazilian rosewood (''
Dalbergia nigra ''Dalbergia nigra'', commonly known as the Bahia rosewood, jacarandá-da-Bahia, Brazilian rosewood, Rio rosewood, jacarandá-do-brasil, pianowood, caviúna, graúna, jacarandá-una or obuina is a species of legume in the family Fabaceae. Descri ...
)'' has become scarce and expensive due to severe trade restrictions (embargo and
CITES CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...
), scarcity and demand. However, in August 2019, CITES announced an exception for rosewood used in musical instruments. The most widely used rosewood used now is
East Indian Rosewood ''Dalbergia latifolia'' (synonym ''Dalbergia emarginata'') is a premier timber species, also known as the Indian rosewood ( Tamil / தமிழ்: Eetti / ஈட்டி) ( Telugu / తెలుగు: Irugudu/ ఇరుగుడు). It is n ...
, often paired with a spruce top for steel string guitars and with spruce or cedar for classical guitars. Another rosewood,
cocobolo Cocobolo is a tropical hardwood of Central American trees belonging to the genus ''Dalbergia''. Only the heartwood of cocobolo is used; it is usually orange or reddish-brown, often with darker irregular traces weaving through the wood. The heartw ...
, is used in upper-end clarinets and guitars. Rosewoods are also the preferred wood for the
Marimba The marimba ( ) is a musical instrument in the percussion family that consists of wooden bars that are struck by mallets. Below each bar is a resonator pipe that amplifies particular harmonics of its sound. Compared to the xylophone, the mari ...
. *
Koa KOA (short for Kampgrounds of America) is an American franchise of privately owned campgrounds. Having more than 500 locations across the United States and Canada, it is the world's largest system of privately owned campgrounds. It was founded ...
is traditionally used for
ukulele The ukulele ( ; ); also called a uke (informally), is a member of the lute (ancient guitar) family of instruments. The ukulele is of Portuguese origin and was popularized in Hawaii. The tone and volume of the instrument vary with size and con ...
s. Koa is also used for steel string guitars mostly due to its beauty and compressed dynamic range. *
Ebony Ebony is a dense black/brown hardwood, coming from several species in the genus '' Diospyros'', which also includes the persimmon tree. A few ''Diospyros'' species, such as macassar and mun ebony, are dense enough to sink in water. Ebony is fin ...
is also often used in many types of instruments for
fingerboard The fingerboard (also known as a fretboard on fretted instruments) is an important component of most stringed instruments. It is a thin, long strip of material, usually wood, that is laminated to the front of the neck of an instrument. The stri ...
s,
tailpiece A tailpiece is a component on many stringed musical instruments that anchors one end of the strings, usually opposite the end with the tuning mechanism (the scroll, headstock, peghead, etc.). Function and construction The tailpiece anchors t ...
s, tuning pegs, and so forth due to its attractive appearance, smoothness to the touch, hardness and wear resistance. Several varieties of ebony are used. Ebony is often dyed to make it appear more uniformly black than the natural wood, which sometimes shows brown streaks. * ''
Paubrasilia ''Paubrasilia echinata'' is a species of flowering plant in the legume family, Fabaceae, that is endemic to the Atlantic Forest of Brazil. It is a Brazilian timber tree commonly known as Pernambuco wood or brazilwood (, ; Tupi: ) and is the na ...
'', commonly called Pernambuco or Brazilwood, is the most sought-after material for the bows of classical stringed instruments, because of its effects on the tones they produce. *
Blackwood Blackwood may refer to: Botany * African blackwood (''Dalbergia melanoxylon''), a timber tree of Africa * African blackwood ('' Erythrophleum africanum''), (''Peltophorum africanum'') also Rhodesian blackwood, trees from Africa * Australian blac ...
(Tasmanian/Australian). *
Walnut A walnut is the edible seed of any tree of the genus '' Juglans'' (family Juglandaceae), particularly the Persian or English walnut, '' Juglans regia''. They are accessory fruit because the outer covering of the fruit is technically an i ...
is often used for the backs and sides of guitars and mandolin family instruments. *
Ash Ash is the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash is the ...
,
Alder Alders are trees of the genus ''Alnus'' in the birch family Betulaceae. The genus includes about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few species ex ...
and
Basswood ''Tilia americana'' is a species of tree in the family Malvaceae, native to eastern North America, from southeast Manitoba east to New Brunswick, southwest to northeast Oklahoma, southeast to South Carolina, and west along the Niobrara River to ...
are commonly used for the bodies of electric guitars, ash for its light-colored, natural wood finishes, and alder and basswood for their uniform density, their ease of machining, and amenability to rapid finishing techniques.


Mechanical properties of tonewoods

Some of the mechanical properties of common tonewoods, sorted by density. See also Physical properties of wood. CFRP, glass, aluminium, and steel added for comparison, since they are sometimes used in musical instruments. Density is measured at 12% moisture content of the wood, i.e. air at 70 °F (21°C) and 65% relative humidity. Most professional luthiers will build at 8% moisture content (45% relative humidity), and such wood weighs less on average than that reported here, since it contains less water. Data comes from the Wood Database, except for 𝜈LR,
Poisson's ratio In materials science and solid mechanics, Poisson's ratio (symbol: ( nu)) is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading. The value ...
, which comes from the Forest Product Laboratory, United States Forest Service, United States Department of Agriculture. The ratio displayed here is for deformation along the radial axis caused by stress along the longitudinal axis. The shrink volume percent shown here is the amount of shrinkage in all three dimensions as the wood goes from green to oven-dry. This can be used as a relative indicator of how much the dry wood will change as humidity changes, sometimes referred to as the instrument's "stability". However, the stability of tuning is primarily due to the length-wise shrinkage of the neck, which is typically only about 0.1% to 0.2% green to dry. The volume shrinkage is mostly due to the radial and tangential shrinkage. In the case of a neck (quarter-sawn), the radial shrinkage affects the thickness of the neck, and the tangential shrinkage affects the width of the neck. Given the dimensions involved, this shrinkage should be practically unnoticeable. The shrinkage of the length of the neck, as a percent, is quite a bit less, but given the dimension, it is enough to affect the pitch of the strings. The sound radiation coefficient is defined as: R = \sqrt where E is
flexural modulus In mechanics, the flexural modulus, bending modulus, or modulus of rigidity is an intensive property that is computed as the ratio of stress to strain in flexural deformation, or the tendency for a material to resist bending. It is determined ...
in Pascals (i.e. the number in the table multiplied by 109), and ρ is the
density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
in kg/m3, as in the table. From this, it can be seen that the loudness of the top of a stringed instrument increases with stiffness, and decreases with density. The loudest wood tops, such as Sitka Spruce, are lightweight and stiff, while maintaining the necessary strength. Denser woods, for example Hard Maple, often used for necks, are stronger but not as loud (R = 6 vs. 12). When wood is used as the top of an acoustic instrument, it can be described using
plate theory In continuum mechanics, plate theories are mathematical descriptions of the mechanics of flat plates that draw on the theory of beams. Plates are defined as plane structural elements with a small thickness compared to the planar dimensions.T ...
and plate vibrations. The
flexural rigidity Flexural rigidity is defined as the force couple required to bend a fixed non- rigid structure by one unit of curvature, or as the resistance offered by a structure while undergoing bending. Flexural rigidity of a beam Although the moment M(x) ...
of an isotropic plate is: D = where E is flexural modulus for the material, H is the plate thickness, and \nu is Poisson's ratio for the material. Plate rigidity has units of Pascal·m3 (equivalent to N·m), since it refers to the moment per unit length per unit of curvature, and not the total moment. Wood is not
isotropic In physics and geometry, isotropy () is uniformity in all orientations. Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix ' or ', hence '' anisotropy''. ''Anisotropy'' is also ...
, but
orthotropic Orthotropic may refer to: * Orthotropic material is one that has different material properties or strengths in different orthogonal directions (e.g., glass-reinforced plastic, or wood) * Orthotropic deck, in bridge design, is one made from solid ...
, so this equation describes the rigidity in one orientation. For example, using 𝜈LR, one gets the rigidity when bending on the longitudinal axis (with the grain), as would be usual for an instrument's top. This is typically 10 to 20 times the cross-grain rigidity for most species. The value for D shown in the table was calculated using this formula and a thickness H of 3 mm. When wood is used as the neck of an instrument, it can be described using
beam theory Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam * Radio beam *Particle beam, a stream of charged or neutral particles ** Charged particle beam, a spatially ...
. Flexural rigidity of a beam (defined as EI) varies along the length as a function of x shown in the following equation: : \ EI \ = \int_^ M(x) dx + C_1 where E is the flexural modulus for the material, I is the
second moment of area The second moment of area, or second area moment, or quadratic moment of area and also known as the area moment of inertia, is a geometrical property of an area which reflects how its points are distributed with regard to an arbitrary axis. Th ...
(in m4), y is the transverse displacement of the beam at x, and M(x) is the
bending moment In solid mechanics, a bending moment is the Reaction (physics), reaction induced in a structural element when an external force or Moment of force, moment is applied to the element, causing the element to bending, bend. The most common or simplest ...
at ''x''. Beam flexural rigidity has units of Pascal·m4 (equivalent to N·m²). The amount of deflection at the end of a cantilevered beam is: w_C = \tfrac where P is the point load at the end, and L is the length. So deflection is inversely proportional to EI. Given two necks of the same shape and dimensions, I becomes a constant, and deflection becomes inversely proportional to E—in short, the higher this number for a given wood species, the less a neck will deflect under a given force (i.e. from the strings). Read more about mechanical properties in ''Wood for Guitars.''


Selection of tonewoods

In addition to perceived differences in acoustic properties, a luthier may use a tonewood because of: * Availability * Stability * Cosmetic properties such as the color or grain of the wood * Tradition * Size (Some instruments require large pieces of suitable wood)


Sources

Many tonewoods come from sustainable sources through specialist dealers. Spruce, for example, is very common, but large pieces with even grain represent a small proportion of total supply and can be expensive. Some tonewoods are particularly hard to find on the open market, and small-scale instrument makers often turn to reclamation, for instance from disused salmon traps in Alaska, various old construction in the U.S Pacific Northwest, from trees that have blown down, or from specially permitted removals in conservation areas where logging is not generally permitted. Mass market instrument manufacturers have started using Asian and African woods, such as bubinga (''
Guibourtia ''Guibourtia'' is a flowering plant genus in the family Fabaceae, also known by the common names as Rhodesian copalwood, African Rosewood, amazique, bubinga, kevazingo, and ovangkol. Description ''Guibourtia'' contains 16 species that are nativ ...
'' species) and wenge (''
Millettia laurentii ''Millettia'' is a genus of flowering plants in the family Fabaceae. It consists of about 169 species of shrubs, lianas or trees, which are native to tropical and subtropical regions of sub-Saharan Africa, the Indian subcontinent, Indochina, sout ...
''), as inexpensive alternatives to traditional tonewoods. The
Fiemme Valley 300px, Location of the Fiemme Valley in Trentino. 300px, The Passo_Lusia.html" ;"title="Lagorai seen from Passo Lusia">Lagorai seen from Passo Lusia. Fiemme Valley (, ) is a valley in the Trentino Provinces of Italy, province, i.e. the southern ...
, in the Alps of Northern Italy, has long served as a source of high-quality spruce for musical instruments, dating from the violins of
Antonio Stradivari Antonio Stradivari (, also , ; – 18 December 1737) was an Italian luthier and a craftsman of string instruments such as violins, cellos, guitars, violas and harps. The Latinisation of names, Latinized form of his surname, ''Stradivarius'', a ...
to the piano soundboards of the contemporary maker
Fazioli Fazioli Pianoforti (), translated as Fazioli Pianos, produces grand and concert pianos from their factory in Sacile, Italy. The company was founded by engineer and pianist Paolo Fazioli in 1981. As of 2016, craftsmen at Fazioli build 140 piano ...
.


Preparation

Tonewood choices vary greatly among different instrument types. Guitar makers generally favor
quartersawn Quarter sawing or quartersawing is a woodworking process that produces quarter-sawn or quarter-cut boards in the rip cutting of logs into lumber. The resulting lumber can also be called ''radially-sawn'' or simply ''quartered''. There is wides ...
wood because it provides added stiffness and dimensional stability. Soft woods, like spruce, may be split rather than sawn into boards so the board surface follows the grain as much as possible, thus limiting
run-out Run-out or runout is an inaccuracy of rotating mechanical systems, specifically that the tool or shaft does not rotate exactly in line with the main axis. For example; when drilling, run-out will result in a larger hole than the drill's no ...
. This is especially important for braces because it maximizes their strength. For most applications, wood must be dried before use, either in air or kilns. Some luthiers prefer further seasoning for several years. Wood for instruments is typically used at 8% moisture content (which is in
equilibrium Equilibrium may refer to: Film and television * ''Equilibrium'' (film), a 2002 science fiction film * '' The Story of Three Loves'', also known as ''Equilibrium'', a 1953 romantic anthology film * "Equilibrium" (''seaQuest 2032'') * ''Equilibr ...
with air at 45% relative humidity). This is drier than usually produced by kilns, which is 12% moisture content (65% relative humidity). If an instrument is kept at a humidity that is significantly lower than that at which it was built, it may crack. Therefore, valuable instruments must be contained in controlled environments to prevent cracking, especially cracking of the top. Some guitar manufacturers subject the wood to
rarefaction Rarefaction is the reduction of an item's density, the opposite of compression. Like compression, which can travel in waves (sound waves, for instance), rarefaction waves also exist in nature. A common rarefaction wave is the area of low relati ...
, which mimics the natural aging process of tonewoods.
Torrefaction Torrefaction of biomass, e.g., wood or grain, is a mild form of pyrolysis at temperatures typically between 200 and 320 °C. Torrefaction changes biomass properties to provide a better fuel quality for combustion and gasification application ...
is also used for this purpose, but it often changes the cosmetic properties of the wood. Guitar builders using torrefied soundboards claim improved tone, similar to that of an aged instrument. Softwoods such as spruce, cedar, and redwood, which are commonly used for guitar soundboards, are easier to torrefy than hardwoods, such as maple. On inexpensive guitars, it is increasingly common to use ''roseacer'' for the fretboard, which mimics rosewood, but is actually a form of thermally-modified maple. "Roasted" maple necks are increasingly popular as manufacturers claim increased stiffness and stability in changing conditions (heat and humidity). However, while engineering tests of the thermally-modified wood indicated increased resistance to humidity, they also showed a significant reduction in strength (ultimate breaking point), while stiffness (flexural modulus) remained the same or was slightly reduced. Although the reduction in strength can be controlled by reducing the temperature of the process, the manufacturer recommends not using its product for structural purposes. However, it is perhaps possible to compensate for this loss of strength in guitars by using carbon-fiber stiffeners in necks and increased bracing in tops.


References


External links

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Commercial article on woods used for woodwind instrumentsGuitarbench's database of tonewood speciesTaylor acoustic guitar woods
String instrument construction Wood by type