American red oak

American red oak (Quercus rubra)

Origin: North America

Nomenclature:

• Polish: dąb czerwony
• English: American red oak, red oak, northern red oak
• French: Chene rouge d’Amerique
• German: Roteiche, Amerikanische Roteiche
• names used in other countries: USA – northern red oak, Czech Republic – dub cerveny, Italy – quercia rossa

Availability
52 mm – KD SE edged – FAS PRIME grade

Occurrence:

Red oak trees naturally occur in the eastern part of North America, where they populate an area from the Great Lakes region in the north to almost Florida in the south. They most often grow in mixed forests, although they sometimes form independent communities. These plants grow best on fresh, moist and semi-permeable substrates. After the species in question was imported to Europe in the 18th century, it was eagerly planted as a park and ornamental tree, and was quickly introduced into forest cultivation. This has also happened in Poland. Red oak wood is also harvested from other oak species found in North America, namely: Quercus falcata, Quercus nigra, Quercus nuttallii, Quercus phellos, Quercus shumardii, Quercus velutina.

Tree habit:

Red oak grows to an average height of up to 35 m, slightly shorter than the two most common native oak species – pedunculate and sessile. The conical crown in young trees transforms into a spreading and domed crown at maturity. Compared to domestic oaks, red oak has several undeniable advantages: it is a less demanding species, can grow on drier and nutrient-poor soils, has much greater resistance to air pollution and low temperatures, and produces a straight, cylindrical trunk that is easy to process into lumber. Besides, red oak trees grow fast and in this respect can be competitive even with beech trees.

Structure type:

Deciduous ring-necked.

Sapwood:

Due to its light whitish or light brown colouration, it is clearly distinguishable from heartwood on all wood cross-sections. It is a narrow-sapwood species (sapwood occupies about 1/8 of the cross-section).

Heartwood:

It has a characteristic pinkish or reddish-brown colour.

Fragrance:

Shortly after being sawn when fresh, the wood gives off a distinct sour smell, which disappears after drying.

Pattern:

The wood has clearly defined annual increments. The wood pattern is very similar to that found in domestic species. The cross-section clearly shows early wood vessels arranged in the form of a ring. Late wood vessels can be seen as lighter streaks (known as flames) arranged parallel to the clearly defined vascular rays. The radial cross-section is richly "decorated" with the indentations of the longitudinally cut vessels, especially the shine, formed from the intersection of high and wide medullary rays. The tangential section also shows vertically running furrows of cut vessels, marking the annual increment boundaries. This cross-section is also enriched by the numerous occurring medullary rays visible as graphite-coloured strands, between 5 mm and 2 cm long (shorter than in European oak wood). Once the wood of the red oak group has been sawn, it is visually impossible to distinguish between the different species.

Typical defects:

Quite numerous knots (hard and darker than the surrounding tissue), radial cracks, frost strips, internal sapwood and sunbursts and tannic stains.

Physical properties of Red Oak wood:

This wood belongs to Class III, i.e. moderately heavy. The average density of heartwood in the air-dry state is approximately 700 kg/m³. The volume shrinkage value (12.9-13.2%) indicates that this species belongs to the medium shrinkage wood according to the Monin classification. Red oak wood also has an average shrinkage anisotropy of -2.1.

Mechanical properties of Red Oak wood:

The considerable density of the wood in question is associated with favourable mechanical properties. The compressive strength depends on the saltiness and ranges from 39 to 61 MPa. The average compressive strength and modulus of elasticity are almost identical to those of domestic oak. The strength of red oak wood is its considerable hardness, averaging 80 MPa on the cross-section.

Hardness:

The natural durability of heartwood of red oak against fungi (on a 5-grade scale) is four (meaning the wood is not very durable). The lack of thylles in the wood is the reason for the lower resistance to biological degradation factors, but allows this wood to be protected with preservatives. Oak heartwood is one of the moderately easy or difficult to saturate with wood preservatives.

Drying:

It is difficult and slow (prone to cracking and warping). It is recommended to protect the faces of the lumber by coating with substances that retard moisture exchange.

Working:

broad oak wood, which contains more latewood, is hard and more difficult to work, while narrow oak wood is lighter and softer and therefore easier to work.

Sanding:

This wood is well sanded and polished; the resulting dust can cause mucous membrane and skin irritation and dermatological problems. Adequate dust extraction is required. Oak dust is suspected of having carcinogenic properties.

Joining:

Bonding goes well, provided the low pH of the wood is taken into account. When connecting with screws and nails, pre-drilling is required. Fasteners containing iron are not recommended due to the risk of corrosion and the appearance of ink staining. Water-based and solvent-based adhesives can be used for bonding small parts. Larger components can be bonded with polyurethane-epoxy, single-component and two-component polyurethane adhesives and hybrids.

Finishing:

A properly prepared surface accepts paints and varnishes well. The low pH of the wood can delay the solidification of some paint and varnish coatings. The use of water-based varnishes can cause discolouration.

Intended use:

Recommended applications for parquet work – In Europe, it is increasingly being used for complex interior decoration, for floors and stairs, facilitated by its attractive colour, additionally deepened by a varnish finish. On the domestic market, American cherry wood is mainly available in the form of lumber, as well as flooring slats, mosaic laths and bonded laminated elements (panels). In the latter, the timber in question forms the upper wear layer visible in the laid floor.
Other uses - North American cherry wood is one of the prized species and has found use in furniture, carpentry and artistic products. It is used to make furniture, panelling, doors, wooden finishes for exclusive yachts, musical instruments and turned and carved parts. At the beginning of the 20th century, cherry wood was also used to finish railway carriages. It is commercially available in the form of logs, lumber and veneers. The popularity of cherry wood in the furniture industry continues to grow due to its ease of working and aesthetic advantages. In the USA, good quality cherry wood is more expensive than oak wood.

Similar species:

Similar species to the wood in question include common cherry, sour cherry and Japanese cherry. This similarity is not limited to appearance, but also applies to physical, mechanical and technological properties.

Notes:

The dust produced during working has an intense odour and irritant properties, and is even included among the substances described as "potentially carcinogenic", although such effects have not yet been duly documented. The low pH of the wood can delay the solidification of some paint and varnish coatings. 

Trivia:

Unlike European oak, the wood of red oak is "hollow", i.e. it is easily permeable to water and is therefore not suitable for the manufacture of barrels and vats and is not used in boatbuilding. This wood lacks the so-called thylles, which enclose the cells specialised in the conduction of water, called vessels. 

• Mechanical properties: good workability; pre-drilling is recommended before nailing. Due to the chemical reaction between the tannins in the wood and the iron, galvanised nails are recommended. Not ideal for adhesives, accepts stain well.
• Modulus of elasticity: 14 GPa
• Volumetric shrinkage: 10.8%
• Specific gravity: 700 kg/m³ (12%)
• Durability: Not resistant to the destructive effects of fungi
• Protections: class 1-2 – accepts preservatives