Robinia pseudoacacia

Robinia pseudoacacia L. – Black locust

group: 	RING-POROUS HARDWOODS

Macroscopic structure of wood

heartwood/sapwood: 	heartwood

description: 	narrow sapwood (1–3 cm), yellowish white; heartwood olive brown

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

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

microvessels arrangement: 	nested arrangement

rays: 	numerous and lustrous ray flecks, visible only in R

texture: 	flatsawn (T), radial figure (R); matte and decorative wood

other: 	wood is often steam then the colour of wood changes to dark brown

Microscopic structure of wood

brief overview: 	Rays 1–6 seriate, HomG; microvessels in nested arrangement, spir. thickenings, tyloses

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: 	nested	X

type of vessel perforation: 	simple	R

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

vessel thickenings: 	fine spiral by late wood vessels	R, T

rays: 	homogeneous	R, T

width of rays	1–6	T, (P)

apotracheal parenchyma: 	marginal	X

paratracheal parenchyma: 	scanty, vasicentric, (confluent)	X

tracheids in basic tissue: 	vascular and vasicentric	R, T

other: 	crystals in ray cells

Wood properties

density: 	heavy

ρ 0: 	760 kg/m3

ρ 12-15: 	800 kg/m3

ρ green: 	1000 kg/m3

shrinkage: 	medium

- volumetric (βV): 	10,3 %

- radial (βR): 	3,9 %

- tangential (βT): 	6,3 %

mechanical properties: 	very strong, elastic and leathery

ultimate strength in compression ||: 	72 MPa

ultimate strength in bending: 	136 MPa

ultimate strength in tension ||: 	140 MPa

hardness: 	hard

Janka's hardness: 	90 MPa

technological properties: 	no problem with working an finishing; uneasy chemical preservation

resistance: 	rated as very resistant to decay

Wood utilization

especially fuel wood, agricultural implements, poles, ladders and garden furniture

References