Spruce wood
| Spruce wood | |
|---|---|
 |
|
| Tree species |
Norway spruce , sitka spruce and others |
| origin |
Europe, Asia, North America |
| colour |
white to yellowish-white; yellowish brown (darkening) |
| Material properties | |
| Axial shrinkage | 0.3% |
| Radial shrinkage | 3.6% |
| Tangential shrinkage | 7.8% |
| Flexural strength | 80 N / mm 2 |
| Compressive strength | 45 N / mm 2 |
| tensile strenght | 95 N / mm 2 |
| Thermal conductivity | 0.1 W / (m K) |
| Fuel properties | |
| Calorific value | 20.2 MJ / kg |
As spruce wood is wood of spruce (genus Picea ) designated as the BSP. also fir , pine or larch wood to the conifers belongs. In Europe and large parts of North Asia, this name almost exclusively refers to the wood of the common spruce ( Picea abies ); in North America, the wood of the sitka spruce ( P. sitchensis ) plays an important role. Internationally, there are a number of other species whose wood is used for different purposes.
Due to the importance of the spruce wood, the common spruce is often referred to as the bread tree of Central European forestry. In Germany, especially in western Germany, the spruce has a share of over 30% of the total forest area with over 3 million hectares. The main deposits are mainly in the high altitudes of the Alps and the low mountain ranges . The range of applications includes, above all, its use as construction and construction wood, packaging wood, raw material for various wood-based materials (multilayer, OSB and chipboard), for paper and cellulose production , as furniture wood for indoor use and as firewood .
Designations
Another name for the wood of the European spruce is red fir because of its reddish color compared to fir wood . Spruce from Scandinavia, Russia and Poland is also known as Nordic spruce . In hardware stores, spruce wood is sold as a mixed range of “white wood” with fir wood. In addition to these designations, there are names that are derived from the growth form of the spruce and suggest corresponding properties of the wood. The names comb spruce , panel spruce and brush spruce refer to the branching of the side branches. In the high mountains the hazel spruce appears as a special growth form, its wood is popular for sound bodies in instrument making.
properties
Spruce trees grow remarkably straight with a solid, cylindrical trunk with few branches in the lower areas. The branch-free trunk lengths reach up to 25 meters with a total height of the tree of up to 60 meters, the diameter is 0.4 to 1.2 meters, and a maximum of about 2 meters. In the open, the trees become more voluminous with significantly greater knots. The wood is light whitish to yellow-whitish with a silky sheen, with heartwood and sapwood not differing in color. Under the influence of light it darkens and takes on a yellowish brown tone. The annual rings are clearly separated from each other, with the color changing continuously from light early wood to dark late wood , the annual ring boundaries are clearly defined. Like other softwoods, with the exception of fir trees, spruce wood has conspicuous resin channels and resin pockets, which means that the wood can be macroscopically distinguished from it by light-colored dots in the cross-section. Another difference can occasionally be deduced from the branch positions: While the branches of the fir tree usually protrude horizontally from the wood and leave correspondingly round knot marks, those of the spruce are oblique and the marks are oval.
Spruce wood is very soft with an average density of 470 kg / m 3 and a moisture content of 12–15%. The density decreases as the tree ring width increases (and with it a relatively smaller proportion of latewood) and the mechanical properties also deteriorate - accordingly, only spruce wood with tree ring widths of 4 to 6 millimeters is permitted for structural timber (DIN 4074-1). The mechanical properties of the wood are very good for its low density, which makes it usable as building and construction wood. Untreated, spruce wood is not very durable if it is exposed to constant alternation between moist and dry. That is why it breaks down quickly when it comes into contact with the ground. For durability outdoors, it is crucial that the wood can dry out and, above all, that the front surfaces are protected from water ( constructive wood protection ). Otherwise the wood must be treated with chemical wood preservatives . At the same time, the wood only has a comparatively low impregnation capacity , which prevents wood moisture levels of more than 20% and the associated fungal attack in treated wood. The processing of the wood by sawing, planing, milling and other techniques is possible without any problems, also the connection with screws and nails as well as glue is problem-free, only trunks with larger knots, resin pockets and reaction wood can have a disadvantageous effect. Paints, glazes and stains can also be used without any effort. Oiling (e.g. linseed oil) only makes the wood slightly darker.
use
Material use
As sawn timber, spruce wood is usually traded and used together with fir wood as a mixed range of spruce / fir; both woods are very similar in their properties. Spruce wood is processed in the form of round timber , sawn timber such as beams, boards and glued laminated timber and as veneer wood . At the same time, it is the most important wood for the production of wood-based materials such as plywood , glued wood , chipboard and fiberboard .
Spruce glued wood
Spruce plywood
Spruce is used almost everywhere as building and construction timber, both in interior construction and in exterior applications. It is used accordingly in house construction for roof structures , for wood paneling, railings, stairs, skeleton structures for walls and ceilings, floors, windows, doors and gates. In furniture construction, spruce wood is used both in solid form and in the form of wood-based materials as blind wood and main wood for simple furniture. There are also a number of other uses such as ladders, concrete shuttering boards, wooden paving, fences, posts, playground equipment and many more. In the packaging area, spruce wood is used to build boxes, pallets and also to produce wood wool . As a special application, evenly grown spruce wood or wood of hazel spruce from the high mountains is used as tonewood for the tops of plucked and stringed instruments and as a soundboard for keyboard instruments.
A central use for the wood of the spruce and other conifers is the manufacture of paper and pulp. Due to the longer fibers compared to hardwoods, their fibers become matted more easily and the paper is stronger.
Energetic use
Spruce wood with a calorific value of 4.5 kWh / kg or 1,500 kWh / rm also plays a central role in the area of energetic use , both in the form of split logs for house firing and in the form of wood chips , wood pellets and briquettes for the corresponding heating systems . As forest and industrial waste wood , it is also used as an energy resource in biomass heating plants and biomass heating power plants.
supporting documents
- ↑ a b c according to DIN 68364 - Characteristic values of wood species - gross density, modulus of elasticity and strength. May 2003.
- ↑ Peter Niemz: Investigations into the thermal conductivity of selected native and foreign wood species . In: Building Physics 29 . tape 29 , no. 4 . Ernst & Sohn Verlag for Architecture and Technical Sciences GmbH & Co.KG, Berlin 2007, p. 311-312 , doi : 10.1002 / bapi.200710040 .
- ↑ Martin Kaltschmitt, Hans Hartmann, Hermann Hofbauer (eds.): Energy from biomass. Basics, techniques and procedures. Springer Verlag, 2nd edition, 2009, ISBN 9783540850946 , p. 360.
- ↑ victories ex. Reforestation guide of the Styrian forest gardens: choice of tree species ( memento of the original from March 20, 2007 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. .
- ^ Gesamtverband Deutscher Holzhandel eV: Wood species ABC: Spruce. accessed on April 3, 2020 at https://www.holzvomfach.de/fachwissen-holz/holz-abc/fichte/
- ↑ according to DIN 4074-1 - sorting of wood according to the load-bearing capacity - part 1: softwood lumber. December 2008.
literature
- D. Grosser, W. Teetz: Spruce . In: Local timber (loose-leaf collection) . Information service wood, wood sales fund - sales promotion fund of the German forest and wood industry, 1998, ISSN 0446-2114 .
- Rosenthal, M .; Bäucker, E. (2012): On the anatomy of the spruce wood. Scanning electron microscope plates.