Niangon
As Niangon the name given to an African is trading wood , the brown reddish to purple one-brown color has the abbreviations according to the DIN EN 13556 for this "HEXN" is. It is characterized by good machinability and is mainly used in exterior construction. In addition, as solid wood, it can replace other woods.
The woods of the two closely related tree species Heritiera utilis and Heritiera densiflora , which cannot be clearly distinguished, are listed under the name Niangon . These belong to the genus Heritiera of the subfamily sterculioideae (Sterculioideae) within the plant family of mallow (Malvaceae).
origin
Niangon is from Africa. The largest amount of Heritiera utilis comes from tropical Africa, mainly from Ghana , Liberia , Sierra Leone , the Central African Republic and the Ivory Coast . Heritiera densiflora comes mainly from Gabon .
Forms of trade
The abbreviation according to DIN EN 13556 for Niangon is HEXN. Further trade names are Nyankom or Wishmore. Sometimes only the wood from Heritiera utilis is named as Niangon, while the wood from Heritiera densiflora in some areas, e.g. B. in Gabon , is called Ogoue . Niangon is traded as round wood , mostly in diameters between 0.6 and 0.8 meters and lengths between 4 and 8 meters. Sizes for window scantlings are preferred as sawn timber . But it is also available in stores in all common dimensions.
description
Niangon can come in different colors. The sapwood is generally gray and usually around 5 centimeters wide. The heartwood is often sharply separated from the sapwood. It has a reddish-brown to purple-brown color and has a matt, glossy finish. If it is dried it looks pink. It looks similar to the Sipo ( Entandrophragma utile ) or Dark Red Meranti . The pores of the wood are scattered, not numerous, but with coarse pores and now and then with dark contents. They are recognizable as strongly curved grooves on the tangential longitudinal plane. The wood rays stand out as 1 to 2 millimeter high, dark, even dashed lines. Otherwise, they shape the wood image as wide, dark-red-brown mirrors. Memory cells cannot be seen with the naked eye. The grain of the wood shows an irregular alternating twist. If the wood is dry, it has a noticeable greasy surface and a slightly rancid odor and thus resembles the linden tree .
properties
Physical Properties
Swell:
| Reference value | values | unit |
|---|---|---|
| Density dried (round wood) | 0.91 | g / cm³ |
| Density air dry (sawn timber) | 0.69 | g / cm³ |
| Density oven dry (0% wood moisture ) | 0.64 | g / cm³ |
| Compressive strength (air dry) | 55 | N / mm² |
| Flexural strength (air dry) | 105 | N / mm² |
Resilience
The wood has a medium resistance to attack by wood-degrading fungi. The natural durability is given in EN 350-2 as class 3. Therefore, it is moderately suitable for outdoor applications.
Machining
With its moderate density and strength, the wood from Niangon is similar to the sawn wood of native oak . However, it has slightly higher values than the wood of the Sipo mahogany . Niangon is very easy to saw, regardless of whether it is fresh or dried. It should be noted, however, that a tooth shape with a large clearance is used. This will prevent clogging and burning.
When planing, there is only a tendency to tear out if there is a strong fiber deviation . Otherwise the planing surface is usually smooth and sharp-edged. After sanding, it is important to remove dust from the surface. Otherwise, the fat content of the wood can lead to sticking.
If a nail or screw is to be inserted into the wood, a pilot hole is advisable. This prevents the wood from bursting. In addition, black-gray discolouration due to ferrous metals and slightly gray discolouration due to brass and copper can occur in damp wood.
Niangon is easy to glue. Problems can only arise with very greasy areas.
Drying
When drying there are no special precautions. It works outdoors and in a drying chamber. Within 3 months, wood that is 34 mm thick and 15 to 40 cm wide can become air dry (15%) when dried in the open air. The risk of tearing or warping is greater in the drying chamber. In order to ensure good stamina in the exterior, drying to 14 to 12% is necessary. In the case of interior work, it has to be 8%.
Surface treatment
Niangon is very easy to treat, although it is greasy in texture. If it is coated with paints and varnishes based on linseed oil, however, it loses this character. Glaze coats , which are increasingly used for exterior construction, are particularly suitable for Niangon . If the required degree of dryness of the wood is adhered to, alkyd , DD , glyptal , nitro and polyester preparations can also be used.
Basically, the surface should be treated by Niangon. Otherwise, in the interior, direct contact with the greasy surface can lead to smearing. In addition, the wood turns gray very quickly, especially outdoors, which can be counteracted with a surface treatment.
Area of use
The largest market for Niangon in Europe is in France . Here it is mainly used for outdoors. It is primarily used as frame wood in window construction, for facade elements, doors, gates, profile boards for wall cladding , for roof underlays and in wooden house construction. Niangon is also processed into parquet or stairs. However, the wood is only suitable to a limited extent for strips and bars. Due to the small cross-sections and the irregular alternating twist, the wood tends to warp, especially when the degree of dryness changes.
Niangon can be used as solid wood as a substitute for the woods Kosig , Rotem Lauen , Seraya , Meranti and Sipo.
literature
- Rudi Wagenführ: Bildlexikon Holz . 2nd, improved and enlarged edition. Fachbuchverlag Leipzig, Munich / Vienna 2004, ISBN 3-446-22851-9 .
- Klaus-Günther Dahms: Small wood dictionary . Wegra publishing company, Stuttgart.
- Anonymous: Information Service Holz-Niangon. Association of German timber import houses e. V., Hamburg
- Anonymous: Handbook of Hardwoods. BRE Princes Risborough, GB 1972.
- Klaus-Günther Dahms: African export woods . DRW-Verlag, Stuttgart 1968.
- Helmut Gottwald: Commercial timbers: Your naming, purpose and Description . Holzmann-Verlag, Hamburg 1959.
Web links
- Niangon. GD Holz - the Gesamtverband Deutscher Holzhandel e. V., accessed on January 14, 2015 .
- Niangon. Holzland.de, accessed on January 14, 2015 .
- Niangon. (PDF) Forestmaine.de, accessed on January 14, 2015 .
Individual evidence
- ↑ Rudi Wagenführ: Bildlexikon Holz. 2nd, improved and enlarged edition. Fachbuchverlag Leipzig, Munich / Vienna 2004, ISBN 3-446-22851-9 .
- ↑ a b K.A. Adam: Heritiera utilis (Sprague) Sprague. (No longer available online.) In: PROTA (Plant Resources of Tropical Africa / Ressources végétales de l'Afrique tropicale), Wageningen, Netherlands. 2005, archived from the original on March 4, 2016 ; accessed on January 15, 2015 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b c d e f g h Niangon. (No longer available online.) GD Holz - des Gesamtverband Deutscher Holzhandel e. V., archived from the original on September 24, 2015 ; accessed on January 14, 2015 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ forestmaine.com (PDF)
- ^ Klaus-Günther Dahms: African export woods. DRW-Verlag, Stuttgart 1968.
- ↑ a b Klaus-Günther Dahms: Small wood dictionary. Wegra publishing company, Stuttgart.
- ↑ a b c holzland.de
- ↑ a b Handbook of Hardwoods. BRE Princes Risborough, GB 1972.
