Quercus robur

Quercus robur L. – Common oak

group: 	RING-POROUS HARDWOODS

Macroscopic structure of wood

heartwood/sapwood: 	heartwood

description: 	narrow sapwood (1–3 cm), yellowish to slightly brown; heartwood light to dark brown

rings: 	distinct boundary between rings; distinct zone of early wood and late wood in rings

vessels:	macropores in early wood (X – holes, R, T – grooves), micropores in late wood (arrangement)

microvessels arrangement: 	in spreading radial arrangement (V)

rays: 	very good visible in X, R, T (T – several cm long vertical lines)

texture: 	flatsawn (T), radial figure (R), very viseble irregular shape ray flack in R; valuable is wood from burls; lustrous and very decorative wood

other: 	vinegary odour; the wood has a corrosive action on metals (iron, steel, lesad), partiularly if the wood ist moist (blue-black colour)

Microscopic structure of wood

brief overview: 	Rays 1 and ∞ seriate, HomG; microvessels in radial arrangement

ring: 	early wood and late wood very good distinct in rings	X

vessel types and arrangements: 	macrovessels in early wood (predominantly solitary), microvessels in late wood (arrangement)	X

microvessels arrangement: 	in spreading radial (V)	X

type of vessel perforation: 	simple	R

tyloses: 	numerous in early wood vessels	X, R, T

rays: 	homogeneous	R, T

width of rays	1 and ∞	T, (X)

apotracheal parenchyma: 	diffuse-in-aggregates	X

paratracheal parenchyma: 	confluent	X

tracheids in basic tissue: 	vascular, vasicentric, fibre tracheids	R, T

Wood properties

density: 	moderate heavy

ρ 0: 	680 kg/m3

ρ 12-15: 	725 kg/m3

ρ green: 	1000 kg/m3

shrinkage: 	medium

- volumetric (βV): 	14,3 %

- radial (βR): 	5 %

- tangential (βT): 	9 %

mechanical properties: 	very strong, elastic

ultimate strength in compression ||: 	61 MPa

ultimate strength in bending: 	88 MPa

ultimate strength in tension ||: 	120 MPa

hardness: 	moderate hard

Janka's hardness: 	67,5 MPa

technological properties: 	no problem with working and finishing, uneasy chemical preservation and drying (it's necessary slowly drying; formation of crack)

resistance: 	rated as very resistant to decay

Wood utilization

timber, inside and outside building constructions, water and bridges constructions, veneers, furniture (garden furniture), turning work, woodcarving, windows, doors, floors, parquet, stairs, inside and outside joinery facings, boat building, mast and tanks

References