In-Depth: Spruce Varieties

Spruce has long been the industry standard for acoustic guitar soundboards. It's been the tonewood of choice since the invention of the steel-string guitar, and was used on stringed instruments for hundreds of years before that. It's high strength-to-wait ratio, clean and traditional appearance and natural abundance has contributed to it's status as the acoustic guitar top wood.

Dig a little deeper though, and there's a dizzying array of spruce varieties used by luthiers across the world. There are dozens of naturally-occuring spruce varieties that are used in instrument building, each with subtly different sonic properties and appearances. Here's our guide to the most common varieties found in guitar building.

Sitka Spruce 

The most commonly used tonewood in the world, Sitka Spruce is the archetypal spruce, found on everything from the most basic beginner's guitars to boutique, custom and bespoke creations from the greatest luthiers in the world. The reason is simple: it's a fantastic all-rounder. Sweet, smooth, balanced and loud, without being harsh or overpowering. A well-built guitar with a Sitka Spruce is a hard instrument to top.

Adirondack Spruce (or 'Red Spruce')

Famously, Adirondack spruce was used during the Golden Era's of Martin and Gibson, and grows in a corridor from Nova Scotia to North Carolina, including the mountain range (itself part of the Appalachians) that shares its name. Favoured by traditionalists and those seeking a vintage tone, Adirondack is a more rigid spruce, with a springier, brasher tone with prominent fundamentals. While a brand-new Adirondack-topped guitar can sound more aggressive, it develops wonderfully over time, for a rich, widescreen sound. 

White Spruce is worth mentioning alongside Adirondack - it typically grows across the Canadian border, but is incredibly similar in tone and look to Adirondack. Carpathian Spruce is another Adirondack-a-like, grown in eastern Europe from American Red Spruce seedlings around the turn of the last century. While it sounds extremely similar to Adirondack, it typically has much wider grain.

European Spruce

European spruce is being used more and more by high-end builders, and it offers some of the headroom of Adirondack and a quicker response than Sitka, but with a warmer, thicker tone. Some builders compare it to a brighter Cedar or Redwood, but with the volume and note-separation of Spruce. It's wonderfully pale in colour, and pairs well with darker timbers like Rosewood or Ebony for a striking two-tone appearance. It benefits from a stronger attack, and louder strummers will love its thick sound even when pushed hard.

European spruce is also known as Alpine, Silver, German, Swiss or Italian spruce, depending on where it was harvested.

Lutz Spruce

Lutz is a naturally occurring hybrid spruce, growing among the Sitka and White Spruce in Western North America. It picks up a bit of each wood's character: high stiffness, low density, and consistent white colour. Visually, it's a very clean and light tonewood with powerful projection. Strong strummers and hard pickers will appreciate the warmth and dynamic response of Lutz.

Engelmann Spruce

Grown in the Western USA, Engelmann is a lighter, less dense spruce variety. While it doesn't have as much headroom as European or Adirondack, it has an older, more mid-focussed sound with wonderful complexity when played softly. It's a perfect choice for fingerpickers and gentler strummers.

Moon Spruce

Moon Spruce is a term for spruce harvested and handled according to a century-old tradition from the mountainous Alp regions in Europe. Carpenters and luthiers noticed that wood that was cut under certain conditions differs from wood that is not cut using the traditional way of handling. These traditional rules for harvesting tonewoods include choosing trees on the northwest slope of a mountain on altitudes over 1000 metres, felling within the last quarter of a waning moon phase, and only in the wintertime - after the growing period of the tree has stopped.

Moon Spruce is typically master-grade European Spruce, and is drier and denser than usual. It has a wonderfully complex, smooth tone with fantastic headroom, and is a creamy white in colour.

Ancient Sitka Spruce

By far the rarest Spruce on our list, a few select builders have begun using 3000-year old Ancient Sitka spruce, unearthed from the Alaskan permafrost. Aside from its breathtaking looks, it has all the attributes of old-growth Sitka: clarity, articulation and touch-sensitivity.

Bearclaw

Bear Claw, also known as Hazelficte, is an asymmetric pattern found on all species of Spruce. It presents itself as fine white lines that will run against the natural grain of the wood. Once thought to be caused by bears sharpening their claw on a tree trunk, Bear Claw is actually just caused by variations in the direction of the wood fibers as a tree grows.When spruce grows it generally has a very straight grain, but sometimes this straight pattern can be interrupted, causing the grain to become wavy in a small portion of the wood.

Bear claw can occur in any variety of spruce, and while opinion is divided as to whether it affects tone, it does create a striking, quilted effect that looks fantastic under a gloss finish.

Torrefied Spruce

Torrefaction is a method of artificially aging spruce soundboards, usually by air-drying the timber in a kiln. Many builders offer this process an optional upgrade and it goes by many names: Baking, Thermo-Cured, Vintage Tone System, Aged-Tone and others.

Torrefied wood sounds broken-in immediately, giving a warmer, drier sound with strong fundamentals and more dynamic range. If you love the sound of vintage guitars, Torrefaction is a fantastic option.