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What is Oak wood, European and American?
Oak is one of the most commonly used hardwoods in Europe and is also widely imported from North America. The wood is known for its light to golden brown or pinkish-brown color and durable properties, making it ideal for a wide range of applications, both indoors and outdoors. Here is a comprehensive description of the characteristics, origin, color and grain, durability, processing, and applications of European and American oak.
Origin
Oak wood comes from trees of the genus Quercus, which grow in the Northern Hemisphere, mainly between the 45th and 50th latitude. In Europe, the growing area is slightly higher due to the maritime climate, while in North America it is lower due to the continental climate. European oak (Quercus petraea and Quercus robur) and American oak (Quercus alba for white oak and Quercus rubra for red oak) are the most common species.
Color and Grain
-
European Oak:
- Heartwood: Light to golden brown.
- Sapwood: Pale.
- Grain: Distinct flames on the flat grain, stripes on quarter-sawn wood.
-
American Oak:
- White Oak: Light to golden brown heartwood, similar to European oak.
- Red Oak: Light brown to pinkish-brown heartwood.
- Grain: Larger growth rings and coarser grain than white oak.
| Characteristic | European Oak | American White Oak | American Red Oak |
|---|---|---|---|
| Heartwood | Light to golden brown | Light to golden brown | Light brown to pinkish-brown |
| Sapwood | Pale | Pale | Pale |
| Grain | Flames on flat grain, stripes on quarter-sawn | Larger growth rings, coarser grain | Larger growth rings, coarser grain |
Durability
- European Oak: Moderately durable to durable (natural durability class II/III).
- American White Oak: Moderately durable to durable (natural durability class II/III).
- American Red Oak: Not very durable (natural durability class IV).
Quality Standards
- European Oak: Belgian standard NBN EN 975-1: 1996 for appearance quality.
- American Oak: American standards or cutting system, where a percentage of the wood surface must be free of defects.
Drying and Moisture Content
Oak wood must be dried in two stages to prevent warping, cracking, and collapse. First, the wood is air-dried to a moisture content of 35-40%, then it is further dried in a drying chamber.
| Drying Process | Description |
|---|---|
| Air Drying | To 35-40% moisture content, out of the sun and strong winds. |
| Drying Chamber | Accelerated drying to the required moisture content. |
Processing
Oak wood is easy to work with both machine and hand tools. The ideal angle for cutting tools is 20°. Pre-drilling is recommended to prevent splitting. Oak wood can be well glued, stained, and lacquered. European oak contains more tannin, which can cause discoloration around metal fasteners.
Technical Specifications
| Property | Value |
|---|---|
| Average density | 710 kg/m³ |
| Radial shrinkage (60-30% r.h.) | 0.8% |
| Radial shrinkage (90-60% r.h.) | 1.2% |
| Tangential shrinkage (60-30% r.h.) | 1.2% |
| Tangential shrinkage (90-60% r.h.) | 2.1% |
| Movement (60-30% r.h.) | 2% |
| Movement (90-60% r.h.) | 3.3% |
| Bending strength | 97 N/mm² |
| Modulus of elasticity | 12,500 N/mm² |
| Compressive strength (parallel to the grain) | 50 N/mm² |
| Shear strength | 10 N/mm² |
| Hardness (Janka) – end | 4900 N |
| Hardness (Janka) – side | 6049 N |
Commercial Dimensions
| European Oak Rough | American Oak Rough |
|---|---|
| Panel and list wood | Panel and list wood |
| Thickness: 13/15/18/20 mm | Thickness: 26/32/40/52/65/80 mm |
| Width: varying widths from 155 mm and wider | Width: varying widths from 155 mm and wider |
| Beam wood | Beam wood |
| Thickness: 18/27/34/41/52/65/70/80 mm | Thickness: 26/32/40/52/65/80 mm |
| Squared timber | Squared timber |
| Thickness: 27/34/41/52 mm | Width: 100 mm and more |
| Length: 400 to 2100 mm and more | Fixed widths: 26×105/26×130/26×155/26×180/26×205 mm |
| Friezes | Friezes |
| Thickness: 20/27/32/41/52 mm | Width: 40/50/60/70/80/90 mm |
| Length: 250 to 2100 mm | Lengths: 2150 to 4900 mm, increasing by 300 mm |
| Rafters | Rafters |
| Thickness: 27×27/30×30/40×40/50×50/60×60/70×70/80×80/100×100 mm | Wood for roof structures in lengths of 400 to 1500 mm and more |
Applications
Oak wood is suitable for various applications, including:
- Indoors: Veneer, parquet, interior doors, furniture, interior trim, baseboards and moldings, stairs.
- Outdoors: Exterior doors, outdoor joinery, cladding, construction timber, hydraulic works (except for American red oak).
Conclusion
Oak wood, both European and American, is a versatile and durable type of wood that can be widely used in both structural and decorative applications. With its attractive color, good workability, and durability, it is an excellent choice for a variety of projects in the construction and furniture industries.