Harps can be made out of virtually any type of wood, but it is important that the wood chosen be strong enough to withstand the significant pressure of the string tension. Some harps are made from plywood (wood that is glued together in layers); some are made from solid wood; and some are made of both solid and plywood.
Wood Strength, Grain, Density & Aesthetics Edit
“It might seem to be stating the obvious that the stronger the wood, the better. But this is simply saying that some wood is too weak to resist warping, cracking, and splitting when the harp is brought up to tension. Likewise the finer the grain, the more the wood is able resonate, so the finer the grain the better. Some wood is so coarse that it is altogether unsuited for harp making. Most pine and fir wood lacks the strength to endure the tension the strings exert on the soundboard or to resist the warp and torque the neck and pillar must withstand. On the other hand, oak is immensely strong but the grain is so coarse (and often irregular) that it has a muffling effect on musical resonance.
"Density is a different matter. It doesn’t go in a continuum of the denser the better or the less dense the better. Density of the wood certainly affects the harp’s characteristic sound but it is not an issue of good or bad, only different from one another. Dense wood has a very bright sound and sharp ring with a quicker decay. Lighter wood has a mellower sound and a more subtle ring with a longer sustain at the same intensity. Both are marvelous and one chooses the effect by choosing the characteristics of the wood.” 
The choice of wood for a harp is a mixture of aesthetics, sound quality, availability, and price. Rarer woods are more expensive, but rare doesn’t necessarily equate to better quality when it comes to harp construction. “There are three basic factors to balance in choosing wood: appearance, price, and sound. The first two are fairly straightforward. People will be drawn visually to a particular wood for many different reasons, and everyone has their own budgetary issues to address. Price relates to the scarcity factor of the wood… Sound, however, can be the hardest to pin down if you aren’t in a position to play and compare the woods first-hand. Because they all sound good, deciding which is “best” becomes purely a matter of personal taste and there is no wrong answer.” 
Various woods produce subtle differences in sound and tone. Some general characteristics of some woods used for building harps are:
Wood for the Body (Hardwoods) Edit
- Bubinga. Deep and full bodied, with an authoritative bass and bell-like treble and mid range.
- Cherry. A warm and sweet tone that is very pleasing and mellow. It darkens with age to a beautiful amber color.
- Cherry (African).
- Cherry (Curly).
- Hawaiian Koa. Both deep and bright, with a strong but very smooth voice. (Dusty Strings)
- Maple. A bright tone that is well-balanced with good projection and a strong fundamental.
- Maple (Birdseye).
- Maple (Curly).
- Maple (Quilted).
- Pine (Swiss).
- Purple Heart.
- Sapele. Bright and clean, with a balance of warmth and depth.
- Walnut. A medium bright, clear, open sound, rich with overtones. 
- Walnut (Black).
- Walnut (Claro).
Wood for the Soundboard (Tonewoods) Edit
- Birch. This section needs more information. Can you help contribute?
- Cedar (Western Red). This section needs more information. Can you help contribute?
- Spruce. This section needs more information. Can you help contribute?
- Spruce (Stitka). This section needs more information. Can you help contribute?
References EditNote about this article. Some of this content has been copy-pasted from Peggy Coates' website dorveille.com The website has disappeared, but the content remains on the internet archives. Attempts have been made to get in touch with the original author, but have been unfruitful. Should Peggy come across this content, please get in touch with @harpwiki!
- ↑ Skeen, James. American Woods in the Construction of Wire-Strung Harps. Retrieved 9/25/11 from http://www.wirestrungharp.com/material/wood/american_wood.html
- ↑ Dusty Strings. Woods. Retrieved from http://www.dustystrings.com/instrumentbuilding/harps/features/woods/tabid/608/Default.aspx
- ↑ Thormahlen Harps. Woods. Retrieved from http://www.thorharp.com/pages/woods.htm