robur L., Quercus petraea Liebl.
|ORIGIN AND SPREAD:
|| Europe till
Asia Minor; both oak kinds not existing in Central and Northern
Scandinavia, both kinds mostly in hardwood mixed forests.
heartwood light-brown to yellowish brown, when fresh it could
be slightly red, boarder of annual rings, spring-wood pores and
wood rays clearly visible; wood rays strikes as a big mirror
IMPORTANT TECHNOLOGICAL FEATURES:
Dry density (grams/cbm) 0,39 – 0,65 – 0,93
Volume shrinking tolerance (in %) 12 – 15
Pressure strength (Newton/qm) 50 – 61 – 90
Bending strength (Newton/qm) 74 – 80 – 105
Tensile strength (Newton/qm) 50 – 90 – 180
E-Modul 10 000 – 12 000 – 13 500
Mechanical treatment is highly
depending on the width of the annual rings; thin wood is to
drill before putting nails and screws; kiln drying moderate;
danger of discolouring, tends to tear and warp; when varnishing
pores needs to be filled;
Heartwood have a high durability when
in water; mostly used as face veneer in the furniture industry;
construction wood for hydraulic engineering and shipbuilding;
special wood for sleepers and barrels; parquet floors, furniture.
Anatomic differences between the two kinds hardly
to distinguish, 3 – 13% of tannin in the core.
Approx. 250 Quercus kinds in Europe are known