The basic properties of spruce and pine are similar in, for example, the long fibers and strength in relation to weight. Differences come up in cell structure: the cell wall in pine sapwood does not close completely, enabling fluid to move freely. This makes chemical treatments like impregnation of pine sapwood possible.
In the heartwood of spruce and pine, the cell wall closes completely and it blocks or complicates movement of fluid. Due to lesser water absorption, spruce and pine heartwood have good weathering resistance in comparison to pine sapwood.
The strength properties of pine are slightly better than those of spruce. The table below shows the most important values of different strength properties (in 15 % moisture content):
Pine (Pinus Silvestris)Spruce (Picea Abies)
Tensile strength (N/mm2)10090
Bending strength (N/mm2)10075Compression strength (N/mm2) Parallel to grain5550Perpendicular to grain7.55.5Modulus of elasticity (N/mm2)1180010500
The reddish colour of pine heartwood distinguishes it from the lighter pine sapwood. In spruce, there are no colour differences between the sapwood and heartwood. The knots are smaller in spruce than in pine, but the amount of knots in spruce is greater; knotless spruce timber is rare.