Oak Natur Thermo-brown stained Character: Course texture and prominent grain having rather dynamic colors but without harsh color variations, with bigger knots. Flame pattern permitted, in a minor degree. Major tint differences may occur between the parquet stripes. Knot: Up to 4-5 knots having a diameter of 20-25 mm are permitted per stripes, except for black knots. Cracked knots are permitted when corrected by filling. Fallen-out knots are permitted, up to 25 mm in diameter, when corrected by filling. Sapwood: Fundamentally, it is not permitted, but healthy tangential sapwood, up to 4-5 mm in width and 50 cm in length, is permissible.
According to the EN 13489 standard, 3 % of different grade than indicated is acceptable.