Spruce wood main physical properties
Spruce's density and hardness is comparable to pine wood, but its processing is much more complicated. Spruce has a small resinous, high resistance to cracking, a lot of round knots on a tangential section. Wood is uniformly-white with a golden hueand it is able to retain the natural color for a long time. Because of its softness, spruce, as pine, should not be used for flooring in areas where it will be constantly exposed heels or where furniture will be installed on the legs with a small area of support. But it will help to create a unique atmosphere at home thanks to warm and light wood tones.
In the forest, spruce grow by one stem with few branches at the bottom and exceptionally straight. Trunk, that is free from branches, reaches 25m in such conditions with a total 60m tree height , diameter ranging from 0.4 to 1.2 m and a maximum of about 2 m. In the open area the crown becomes more voluminous and the knottiness becomes higher. Wood is whitish or yellowish-white with a silky luster, and the heartwood and sapwood are not distinguished by color. Under the influence of light, it darkens and takes the yellow-brown hue.
Annual rings are clearly distinguishable, and the color of light early wood smoothly turn into dark, the boundaries of growth rings clearly defined. Like other conifers spruce wood has a notable pockets of resin ducts, forming a cross section of light dotted pattern.Fir doesn't have this feature that allows to distinguish them from each other. Another difference is the location of branches on the stem: as a rule fir boughs branch off at right angle, that is why big marks are remained on the trunk, and spruce boughs branch off at an angle and remain oval marks.
Spruce wood is very soft and has an average density of 470 kg / m ³ at 12-15% humidity. With the increase of tree rings (and the associated decrease in the proportion of late wood), the density is reduced, mechanical properties also deteriorate - only pine wood with wide growth rings from 4 to 6 mm (DIN 4074-1) is suitable for construction . The mechanical properties of wood for such a low density are very good, that is why spruce is used as a building and structural wood. However, in raw form spruce is short-lived under the influence of weather factors, and in contact with the ground rots quickly, for outdoor use this timber must be properly chemically treated. At the same time spruce has a relatively low impregnability, humidity is about 20% and connected with this mashroom defeat prevents impregnation.
Spruce is easily handled by sawing, planing, milling and other techniques, the connection by screws, nails and glue don't provoke any difficulties, but stems with a high knotty, resin pockets and internal stresses could change their shape after use. Painting, coating and staining does not cause problems.
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