Rustic grade oak is characterised by the number of knots and colour unevenness.
Rustic oak has unlimited number of fine and up to 60 mm knots.
Fallen knots are being filled with special oak filler.
Small hallows are acceptable.
The central core is allowed.
Oak grain pattern is heavily exposed.
Nature grade wood product range includes natural-looking wood planks.
Natural wood-grained pattern is clearly visible.
The colour tones show a set of knot locations, unlimited number of small knots.
Allowed up to 20 mm knots, which are filled.
Sapwood, central core, cracks and knots on edge are not allowed.
Select/prime grade oak wood is carefully selected.
A natural wood tree-ring pattern and medullary rays are visible.
Single knots up to 5 mm are allowed with no fillings.
Any other defects are not allowed.
Wood pattern and colour tone depends on a wood-tree pattern, what is typical for the oak wood texture.