Alnus glutinosa

'Alnus glutinosa'' Gaertn. – Common alder'''

group: 	DIFFUSE-POROUS HARDWOODS

Macroscopic structure of wood

heartwood/sapwood: 	sapwood

description: 	pinkisch to light reddish brown colour (dark orange when first cut)

rings: 	small visible boundary between rings

vessels:	only micro pores in wood (longitudinal sections smooth)

rays: 	aggregate rays, visible in X, R, T (T – several cm long vertical lines, R – irregular shape ray flack)

texture: 	slightly flatsawn (T) and slightly radial figure (R); little decorative wood

other: 	very often occuence of pith fleck (reddish brown colour)

Microscopic structure of wood

brief overview: 	Ray 1 seriate, HomG + aggregate rays; scalariform perforation plate

ring: 	invisible boundary between early and late wood within ring	X

vessel: types and arrangements: 	only microvessels; microvessels solitary or in radial multiples (up to 4)	X

type of vessel perforation: 	scalariform	R

rays: 	homogeneous + aggregate rays	R, T

width of rays	1 (in aggregate rays 1–3)	T, (X)

apotracheal parenchyma: 	slightly numerous – marginal, diffuse	X

tracheids in basic tissue: 	numerous fibre tracheids, possible occurrence vascular and vasicentric	R, T

other: 	often occurrence of pith flecks

Wood properties

density: 	light

ρ 0: 	495 kg/m3

ρ 12-15: 	530 kg/m3

ρ green: 	850 kg/m3

shrinkage: 	medium

- volumetric (βV): 	13,1 %

- radial (βR): 	4,6 %

- tangential (βT): 	8,5 %

mechanical properties: 	weak, brittle

ultimate strength in compression ||: 	55 MPa

ultimate strength in bending: 	97 MPa

ultimate strength in tension ||: 	94 MPa

hardness: 	soft

Janka's hardness: 	40 MPa

technological properties: 	no problem with drying, working and finising

resistance: 	rated as slightly resistant to decay

Wood utilization

veneers, plywoods, particleboards, woodcarving, turning work, boat building, various objects (pencils, racks, picture frames), furniture (imitation of ebony and other tropical wood species in the past)

References