Grades and Specification for birch square edge timber

Grades and Specification for birch square edge timber

Original http://www.russianbirchlumber.com/russian-birch-timber-contacts

Moisture content 10% (+/- 2%)

Length: 2,0 – 4 m with pace 500 mm. The prevailing length is 2 m.

Length allowance is +2 cm.

Width: 70-200 mm with any pace (the material can be cut with fixed widths 75;100;125;150 mm or other fixed widths)

Thickness: 25 mm. The boards can be cut with 50 mm thickness.

Thickness tolerance: -0+2 mm

Width tolerance: -0+2 mm

Flaws Grade 1 (AA) Grade 2 (AB) Grade 3 (BB) Grade 4 (BC) Grade 5 (CC)
Live knots (knots below 5 mm in diameter are to be disregarded) Through knots on both faces are permissible 1 knot per 1 linear meter For better face 1 knot   per 1 LM is permissible.  For worse face it is not limited unless it may affect the strength of material. Permissible without limitations. Permissible without limitations. Permissible without limitations.
Black knots (loose, decayed and tobacco ones are not permissible) Not permissible Not permissible for the better face. For the worse face black knots are permitted without limitations, excluding loose, decayed and tobacco ones. The knots are permitted without limitations. The knots are permitted without limitations. Loose knots are not permitted. The knots are permitted without limitations. Loose knots  are not permitted.
End cracks 20 mm long non-through cracks. Through cracks are not permissible. 40 mm long non-through cracks. 20 mm long through cracks. 50 mm long non-through cracks. 30 mm long through cracks. 70 mm long non-through cracks. 50 mm long through cracks. Any non-through cracks are permitted. 60 mm long through cracks.
Face shakes Not permissible Fine checks up to 20 mm in length are permissible. Fine checks up to 40 mm in length are permissible. Fine checks up to 60 mm in length are permissible. Permissible, if a board integrity is maintained.
Full-width wane Not permissible Not permissible Not permissible Not permissible Permissible at a board end up to 7 cm long
Half-width wane Not permissible Permissible for the worse face; width 5 mm, length 15 cm Permissible for the worse face; width is 1/3 of a board’s thickness, length 20 cm Permissible for the worse face; width is 1/2 of a board’s thickness, length 30 cm Permissible for the worse face; width is 2/3 of a board’s thickness, length 30 cm
Bow 1mm per 1 m 2 mm per 1 m 7 mm per 1 m 7 mm per 1 m Permissible
Cupping 2% of face width 2% of face width 2% of face width 2% of face width Permissible
Mechanical damage Not permissible Broken wood at the wane, torn grain at knots up to 2 mm in depth. Broken wood at the wane, torn grain at knots up to 2 mm in depth. Broken wood at the wane, torn grain at knots up to 2 mm in depth. Permissible
False heartwood Not permissible Not permissible Random sound heartwood 5×5 cm on the worse face Sound heartwood is permissible for the worse face  with no limitations; for other not permissible Permissible if without soft rot
Hard rot Not permissible Not permissible Not permissible 5% of a board area is permitted 15% of a board area is permitted
Soft rot Not permissible Not permissible Not permissible Not permissible Not permissible
Mould Not permissible Not permissible 5% of a board area is permitted 15% of a board area is permitted Permissible
Bluestain Not permissible Not permissible Not permissible 5% of a board area is permitted 15% of a board area is permitted

Packaging

Dimensions of a made-up package:1,1 m x 1,1 m x board length

The boards are stacked into a compact package, each 8-10 rows are separated with a spacer, minimum 10mm and maximum 20 mm in thickness.

PE film is laid under the bottom and top rows.

Five sides of a package are wrapped with film.

Packages are bundled with a PET tape at intervals of 80 cm with the last tape placed on the distance of 20 cm from the end of the package.

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