On Piano Soundboard Manufacturing

Soundboard Production
and the Spruce Forests of North American

The perfect materials for Piano Soundboard Manufacturing

Our customers interested in what makes a good and enduring piano, as well as what kind of piano -- grand, baby grand or otherwise -- is worthy of restoration and rebuilding, often ask about the soundboard. "What type of wood is used for the soundboard?" "Do some types of wood resonate better than others?" "Are there other materials besides wood that can be or that have been used for soundboard production?"

Since piano manufacturing became a well established, thoroughly researched and tested industry, spruce wood -- especially old-growth spruce -- became the primary choice of wood types for making piano soundboards. There are several technical reasons for this.

First, spruce wood has the desired density as a sound resonator, whereas other types of conifers are either too dense or not dense enough for resonating the vibrations made from the hammer striking the strings. This is not to say that other types of conifers cannot be used as soundboards; it's just that spruce wood happens to be the best for such a purpose. Other types of conifers have been used -- Cypress, for example, but spruce has proven to be the optimal resonator.

Second, the old-growth spruce forests of Northern Europe and North America had more or less stable growing conditions for hundreds of years. Such long growing conditions allowed the trees to grow to great heights and widths. The result for woodworking was trees with very large interiors made of straight grain, free of knots. Plus, such long, relatively stable growing conditions produced lumber with very even rings of grain which makes the wood the desired strength and elasticity needed for piano soundboard manufacturing.

In early theoretical accounts of piano construction, writers offered reasons for spruce wood's superior qualities. For example, Samuel Wolfenden suggests in The Art of Pianoforte Construction, originally published in 1916, that "the annual rings of hard and soft grain are far more regular than in most other woods" (Wolfenden. 89). He goes on to say:

It has been suggested that the suitability of this wood for sound-boards arises from the fact that there is a kind of rough average proportion between the amount of the soft wood, that which is formed early in each season, and that which is formed in the later part of each year's growth, the proportion being affirmed to be as two of soft to one of hard. (Wolfenden. 90)

Wolfenden goes on to suggest that no ultimate conclusion has been made as to why spruce wood is superior, but he does give three reasons that we can be sure of. 1) "(Spruce) transmits vibrations lengthwise of its grain with greater rapidity than most other woods..." 2) "the wood is exceedingly light, and therefore easily responsive to the minute shocks communicated through the bridges..." and 3) "it is both very flexible and elastic..." (Wolfenden. 90 - 91)

In Europe, by the end of the 19th Century, the old growth conifer forests of the northern climates had already been heavily logged, not specifically for piano soundboard production, of course, but more for the building of cities, wooden ships, carriages, and a thousand other utilitarian uses. As good wood became more and more scarce, piano builders began experimenting with other refined, abundant materials, especially different types of metal, such as steel, copper and aluminum. These metals do, indeed, resonate, and their producers were quick to point out qualities in metal that wood did not and could not have, such as enduring strength, the complete lack of knots and the resistance to cracks. But time and again, such experiments with these different, less traditional materials confirmed what both trained percussionists (including pianists) as well as stringed musicians were hearing: when it comes to the need for a high quality resonator, there is no adequate substitute for the wood of cone bearing trees.

In Wolfenden's treatise, he goes on to explain how the goal of the soundboard is the concurring distribution of the string's vibratory effects, and although metal as a resonator is able to accomplish the desired result, piano makers found the metal substitutes especially lacking in elasticity, as well as the ability of spruce wood to adequately translate the most subtle vibrations emitted by the bridge. Not only this, but the metal substitutes were by far too heavy for practical transport of the piano from place to place.

The eventual lack of good wood for soundboard manufacturing in Europe gave American piano manufacturers a significant advantage as piano builders in Boston, Philadelphia, Baltimore, New York City, and even Chicago had the seemingly endless supply of old growth spruce wood from Canada's conifer forests, as well as the forests of New Hampshire's famed White Mountains, north to the densely wooded interiors of Maine and northern New York.

Notes and Sources

1989. S. Wolfenden, A Treatise on the Art of Pianoforte Construction. Heckscher & Co. Limited, London (Originally published in 1916).

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