Spruce

Spruce is the wood of trees in the genus Picea, a group of tall, straight, cone-bearing conifers. In Northern Europe the dominant commercial species is Norway spruce (Picea abies), though the genus spans some three dozen species across the boreal and northern temperate forests of Europe, Asia, and North America. It is one of the most widely grown and heavily used softwoods in the world, supplied in enormous volume as construction lumber and pulpwood.

At a glance the wood is very pale — a light cream to pale tan, as seen on this sample — with a fine, uniform grain and little contrast between growth rings. It is light and soft, yet notably strong and stiff for its low weight, a strength-to-weight ratio that has made it valued far beyond ordinary framing lumber, most famously as the soundboard wood in violins, guitars, and pianos.

There is essentially no color distinction between heartwood and sapwood: both are pale, running from near-white to a light cream or pale yellow-tan, sometimes with a faint reddish or pinkish cast. The grain is normally straight and the texture fine and even, with narrow, gently defined growth rings; the latewood bands are subtle rather than the hard contrasting stripes seen in southern pines. Luster is medium and the surface has a clean, slightly silky sheen. The wood is non-resinous to the eye — it lacks the greasy resin canals and pitch pockets that mark pine, though small resin canals are present.

Spruce is light and physically soft, with a Janka hardness around 380 lbf for Norway spruce — well into the soft range and dent-prone in service. Despite this it is comparatively strong, stiff, and resonant for its density, which is the quality prized in structural and musical use.

Natural durability is poor. The heartwood is rated non-durable to perishable, with little resistance to decay or insects, and it is also resistant to preservative treatment. Spruce is therefore an interior or protected-use wood unless kept dry or properly finished.

The bulk of spruce is used as general construction and framing lumber, where it is often sold under the mixed-species grade group SPF (spruce-pine-fir). It is a leading pulpwood for paper, and a core species for plywood, glulam beams, laminated stock, and the light softwood laminate seen on this sample. It also serves for interior joinery, boxes, crates, pallets, ladders, and utility millwork.

Where spruce truly stands out is as a tonewood. Its high stiffness-to-weight ratio and even grain make it the classic soundboard material for violins and the rest of the string family, acoustic and classical guitars, pianos, and harps; European (Norway) spruce and the related Sitka spruce are the benchmark woods for this work. Historically, straight-grained spruce was also the premier wood for aircraft spars, masts, and oars, again for its strength at very low weight.

Spruce is easy and pleasant to work with both hand and machine tools. It cuts, planes, and sands readily, and being light and soft it saws with little effort. Sharp tools are important: dull edges will crush the soft earlywood and leave a fuzzy or torn surface, especially around knots, which are common and can be hard and loose. It holds nails and screws adequately though its softness means fasteners grip less firmly than in dense hardwoods.

It glues very well — a key reason it is used in laminated and engineered stock — and takes paint and clear finishes well, though as a soft, porous softwood it can absorb stain unevenly and blotch without a conditioner. It dries readily and is fairly stable once seasoned.

Spruce is not considered a toxic wood, and it is generally low on the list of sensitizing timbers. As with any wood, however, its fine dust can irritate the eyes and respiratory tract and has occasionally been associated with respiratory or skin reactions in sensitive individuals, so use dust extraction and a mask. There are no CITES or endangered-species concerns for the common commercial spruces.

Spruce is inexpensive and abundantly available. As one of the principal softwoods of the Northern Hemisphere it is produced in huge volumes for construction and pulp, and dimensional spruce lumber is among the cheapest solid wood on the market. Select, tight-grained, defect-free stock cut for instrument soundboards is the exception — high-grade tonewood spruce commands a substantial premium and is sold in small, carefully graded pieces.

The common commercial spruces are not CITES-listed and are not considered threatened; they are fast-growing, widely cultivated, and extensively managed in plantation and boreal forestry. FSC- and PEFC-certified spruce is readily available, making it an easy sustainable choice for everyday work.