Alder wood
| alder | |
|---|---|
 |
|
| Tree species | |
| origin |
Europe |
| colour |
light, reddish white, reddish yellow to reddish brown |
| Material properties | |
| Bulk density mean | 510-550 kg / m³ |
| Raw density limit values | 450-640 kg / m³ |
| Axial shrinkage | 0.4% |
| Radial shrinkage | 4.3% |
| Tangential shrinkage | 9.3% |
| Flexural strength | 85-97 N / mm² |
| Compressive strength | 47-55 N / mm² |
| tensile strenght | 94 N / mm² |
| Thermal conductivity | 0.109 W / (m K) |
| Fuel properties | |
| Calorific value | 4.1 kWh / kg |
As alder wood is wood of various kinds of alder (genus Alnus ) designated as lumber may be used. In Europe this is mainly the black alder ; the wood of the gray alder is used less often.
According to DIN 4076, "ER" is the abbreviation for black alder and gray alder.
origin
The wood of the black alder ( Alnus glutinosa ) and the gray alder ( Alnus incana ) is used as alder wood . The natural distribution area of the black alder extends almost over the whole of Europe to the Caucasus and Siberia . However, it is absent in central and northern Scandinavia , in southern Spain and in the southern Russian steppe area. They can also be found in North Africa and the Middle East. The natural range of the gray alder is less extensive than that of the black alder, it is absent in the south and west of Europe, but it can be found further north and further east.
Appearance
Alders belong to the sapwood trees, so heartwood and sapwood are not different in color. The wood is reddish white, reddish yellow to light reddish brown, but darkens when exposed to light. Freshly felled wood appears noticeably orange-red due to oxidation, but the color disappears again as the wood dries out. There are numerous fine vessels in the wood, which are arranged in scattered pores. Wood rays are not very pronounced and are only noticeable as inconspicuous mirrors on the radial surfaces . However, the wood rays are often bundled into pseudo-wood rays, which are then more clearly visible. The annual ring boundaries are not very pronounced, but the annual rings are clearly recognizable by the less pore-free and denser latewood. Alder wood often shows pith marks. The wood of the gray alder is similar to the wood of the black alder, but is a little lighter, less coarse-grained and more shiny.
properties
Alder wood is soft and has an even, fine structure. It has a gross density of 550 kg / m 3 with a wood moisture content of 12 to 15% and thus belongs to the medium-heavy native wood species. The wood is not very strong and also not very elastic and in these properties it is comparable to linden wood . Exposed to the weather or in contact with the earth, it is not very durable, but when installed under water it shows a similarly high durability as oak wood . Alder wood dries well and quickly without cracking or warping. The wood is easy to work with and can be easily sawed, sliced and peeled, it is easy to mill , turn and carve . Screws hold well and can be glued well, but the wood is not very nail-proof and tends to splinter when nailing. Surface treatment such as polishing, pickling and painting is unproblematic. When it comes into contact with iron, gray discolouration occurs in the presence of moisture, and the iron itself corrodes. Alder wood is also reactive in contact with alkalis such as cement and lime , losing its color and turning gray. Otherwise the wood is generally not very chemically active.
There are hardly any differences between the wood of the black alder and the gray alder in terms of physical or mechanical properties; the wood of the black alder is somewhat heavier, stronger and shrinks less than that of the gray alder.
use
For most of the applications described here, both black alder wood and gray alder wood can be used. The wood of the gray alder is used less often, because the gray alder hardly reaches dimensions suitable for useful wood and the trunk shape is usually unfavorable. Only under optimal conditions, such as in the Baltic States and Finland, does it grow into straight, smooth-stemmed, larger-sized trees.
The wood is used as pulpwood for the production of chipboard, chipboard molded parts and fibreboard, whereby it is added to the main types of wood such as pine, spruce and beech. It also makes a good starting material for making paper. It is used as firewood, but is also used for turning and for making toys and wooden shoes. The alder provides a high-quality blind wood for furniture and interior fittings. Due to its good pickling properties, alder is used to imitate precious woods such as cherry, walnut, mahogany and ebony and for the restoration of furniture. Alder wood is used to make packaging boxes and disposable pallets, and it is used inside transport boxes as toothed strips to fix accessories or machine parts. It is used to make casting models. In the musical instrument making parts of accordions are made of alder wood, also instrument necks of inexpensive variants of the plucked instruments guitar, lute and mandolin are made of alder wood. Alder wood is also widely used as a material for the bodies of electric guitars . Special charcoals are also made from alder wood, which are used as drawing charcoal , soldering charcoal and laboratory charcoal .
Due to its good durability under water, the wood is well suited for hydraulic engineering and earthworks. It was therefore often used in the past as pile wood, for lock gates, spring enclosures, well troughs and water pipes. Many European pile-dwelling settlements were built from alder wood, Venice is also said to be built half on oak and half on alder wood.
Before the First World War , alder wood was also the starting material for the molding industry in Berlin , at that time the third most important branch of industry in the capital. The wood came from East German and Eastern European areas.
literature
- D. Grosser, W. Teetz: Erle . In: Arbeitsgemeinschaft Holz e. V. (Ed.): Local timber (loose-leaf collection) . No. 16 . Information service wood, wood sales fund - sales promotion fund of the German forest and wood industry, 1998, ISSN 0446-2114 .
Web links
Individual evidence
- ↑ 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 .
- ↑ Wood calorific values. kaminholz-wissen.de, accessed on January 1, 2010 .
- ↑ a b c d e f g h Grosser, Teetz: Erle
- ↑ a b Schütt, Weisgerber, Schuck, Lang, Stimm, Roloff: Encyclopedia of the deciduous trees . Nikol, Hamburg 2006, ISBN 3-937872-39-6 , pp. 97-106 .
- ↑ D. Grosser, W. Teetz: Erle . In: Local timber (loose-leaf collection) . No. 16 . Information service wood, wood sales fund - sales promotion fund of the German forest and wood industry, 1998, ISSN 0446-2114 .
- ↑ Tony Bacon, Dave Hunter: Totally Guitar - the Definitive Guide (Guitar Encyclopedia , English), p. 27. Backbeat Books, London 2004. ISBN 1-871547-81-4
- ↑ Doris Laudert: Myth Tree . 7th edition. BLV, Munich 2009, ISBN 978-3-8354-0557-8 , p. 114-117 .