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Comparison of plywood grades in accordancewith STO 15605981-001-2023

Wood flaws and defects
B (I)
Grade
S (I)
Grade
BB+ (II)
Grade
BB (II)
Grade
CP (III)
Grade
C (IV)
Grade
1. Pin knots
Grade B (I)
Pin knots
Allowed
Grade S (I)
Pin knots
Allowed
Grade BB+ (II)
Pin knots
Allowed
Grade BB (II)
Pin knots
Allowed
Grade CP (III)
Pin knots
Allowed
Grade C (IV)
Pin knots
Allowed
2. Inter-grown sound knots both light and dark
Grade B (I)
Inter-grown sound knots both light and dark
Ignored up to 10 mm. Light knots with a diameter of up to 15 mm with a crack of up to 0.5 mm of up to 5 pcs/m2 are allowed
Grade S (I)
Inter-grown sound knots both light and dark
Ignored up to 10 mm. Knots with a diameter of up to 15 mm with a crack of up to 0.5 mm of up to 5 pcs/m2 are allowed
Grade BB+ (II)
Inter-grown sound knots both light and dark
Knots with a diameter of up to 25 mm with a crack of up to 1 mm of up to 10 pcs/m2 are allowed
Grade BB (II)
Inter-grown sound knots both light and dark
Knots with a diameter of up to 25 mm with a crack of up to 1 mm of up to 10 pcs/m2 are allowed
Grade CP (III)
Inter-grown sound knots both light and dark
Allowed with a crack of up to 1.5 mm in width
Grade C (IV)
Inter-grown sound knots both light and dark
Allowed
3. Partially inter-grown knots
Grade B (I)
Partially inter-grown knots
Allowed with a diameter of up to 6 mm of up to 3 pcs/m2
Grade S (I)
Partially inter-grown knots
Allowed with a diameter of up to 6 mm of up to 3 pcs/m2
Grade BB+ (II)
Partially inter-grown knots
Allowed among inter-grown knots with a diameter of up to 15 mm of up to 10 pcs/m2
Grade BB (II)
Partially inter-grown knots
Allowed among inter-grown knots with a diameter of up to 15 mm of up to 10 pcs/m2
Grade CP (III)
Partially inter-grown knots
Allowed among inter-grown knots with a diameter of up to 15 mm of up to 10 pcs/m2
Grade C (IV)
Partially inter-grown knots
Allowed any quantity of up to 40 mm in diameter
4. Loose knots, with knotholes therefrom (w/o bark)
Grade B (I)
Loose knots, with knotholes therefrom (w/o bark)
Allowed with a diameter of up to 6 mm of up to 3 pcs/m2
Grade S (I)
Loose knots, with knotholes therefrom (w/o bark)
Allowed with a diameter of up to 6 mm of up to 3 pcs/m2
Grade BB+ (II)
Loose knots, with knotholes therefrom (w/o bark)
Allowed with a diameter of up to 6 mm of up to 4 pcs/m2
Grade BB (II)
Loose knots, with knotholes therefrom (w/o bark)
Allowed with a diameter of up to 6 mm of up to 6 pcs/m2
Grade CP (III)
Loose knots, with knotholes therefrom (w/o bark)
Allowed with a diameter of up to 6 mm of up to 10 pcs/m2
Grade C (IV)
Loose knots, with knotholes therefrom (w/o bark)
Allowed any quantity of up to 40 mm in diameter
5. Close cracks
Grade B (I)
Close cracks
Allowed up to 200 mm in length of up to 5 pieces per 1 m of sheet width
Grade S (I)
Close cracks
Allowed up to 200 mm in length of up to 5 pieces per 1 m of sheet width
Grade BB+ (II)
Close cracks
Allowed up to 300 mm in length of up to 5 pieces per 1 m of sheet width
Grade BB (II)
Close cracks
Allowed up to 300 mm in length of up to 5 pieces per 1 m of sheet width
Grade CP (III)
Close cracks
Allowed
Grade C (IV)
Close cracks
Allowed
6. Open cracks
Grade B (I)
Open cracks
Not allowed
Grade S (I)
Open cracks
Allowed up to 200 mm in length and up to 1 mm in width of up to 2 pieces per 1 m of the sheet width
Grade BB+ (II)
Open cracks
Allowed up to 200 mm in length and up to 1 mm in width of up to 2 pieces per 1 m of the sheet width
Grade BB (II)
Open cracks
Allowed up to 250 mm in length and up to 2 mm in width of up to 3 pieces per 1 m of the sheet width. Subject to be filled with putties
Grade CP (III)
Open cracks
Allowed up to 600 mm in length and up to 2 mm in width of up to 2 pieces per 1 m of sheet width; allowed up to 600 mm in length and up to 5 mm in width. Subject to be filled with putties
Grade C (IV)
Open cracks
Allowed any quantity of up to 600 mm in length and up to 5 mm in width
7. Light inner inbark
Grade B (I)
Light inner inbark
Allowed
Grade S (I)
Light inner inbark
Allowed
Grade BB+ (II)
Light inner inbark
Allowed
Grade BB (II)
Light inner inbark
Allowed
Grade CP (III)
Light inner inbark
Allowed
Grade C (IV)
Light inner inbark
Allowed
8. Dark inbark
Grade B (I)
Dark inbark
Allowed in general quantity and with standards for black knots
Grade S (I)
Dark inbark
Allowed in general quantity and with standards for black knots
Grade BB+ (II)
Dark inbark
Allowed in general quantity and with standards for sound knots
Grade BB (II)
Dark inbark
Allowed in general quantity and with standards for sound knots
Grade CP (III)
Dark inbark
Allowed in general quantity and with standards for sound knots
Grade C (IV)
Dark inbark
Allowed any quantity of up to 40 mm in diameter
9. Deviations in wood structure (curly grain, dip grain, burr, inclination of grain)
Grade B (I)
Deviations in wood structure (curly grain, dip grain, burr, inclination of grain)
Allowed
Grade S (I)
Deviations in wood structure (curly grain, dip grain, burr, inclination of grain)
Allowed
Grade BB+ (II)
Deviations in wood structure (curly grain, dip grain, burr, inclination of grain)
Allowed
Grade BB (II)
Deviations in wood structure (curly grain, dip grain, burr, inclination of grain)
Allowed
Grade CP (III)
Deviations in wood structure (curly grain, dip grain, burr, inclination of grain)
Allowed
Grade C (IV)
Deviations in wood structure (curly grain, dip grain, burr, inclination of grain)
Allowed
10. Sound discoloration (false heart)
Grade B (I)
Sound discoloration (false heart)
Not allowed
Grade S (I)
Sound discoloration (false heart)
Not allowed
Grade BB+ (II)
Sound discoloration (false heart)
Not allowed
Grade BB (II)
Sound discoloration (false heart)
Allowed up to 25% of the sheet surface
Grade CP (III)
Sound discoloration (false heart)
Allowed up to 75% of the sheet surface
Grade C (IV)
Sound discoloration (false heart)
Allowed
11. Sound discoloration (block mottle, vein lines, vein marks)
Grade B (I)
Sound discoloration (block mottle, vein lines, vein marks)
Allowed the light ones in the area of up to 15% of the sheet surface
Grade S (I)
Sound discoloration (block mottle, vein lines, vein marks)
Allowed the light ones in the area of up to 15% of the sheet surface
Grade BB+ (II)
Sound discoloration (block mottle, vein lines, vein marks)
Allowed the light ones in the area of up to 15% of the sheet surface
Grade BB (II)
Sound discoloration (block mottle, vein lines, vein marks)
Allowed
Grade CP (III)
Sound discoloration (block mottle, vein lines, vein marks)
Allowed
Grade C (IV)
Sound discoloration (block mottle, vein lines, vein marks)
Allowed
12. Sound discoloration (group veins)
Grade B (I)
Sound discoloration (group veins)
Allowed up to 60x40 mm of up to 1 pcs/m2
Grade S (I)
Sound discoloration (group veins)
Allowed up to 60x40 mm of up to 1 pcs/m3
Grade BB+ (II)
Sound discoloration (group veins)
Allowed up to 60x40 mm of up to 1 pcs/m4
Grade BB (II)
Sound discoloration (group veins)
Allowed
Grade CP (III)
Sound discoloration (group veins)
Allowed
Grade C (IV)
Sound discoloration (group veins)
Allowed
13. Chemical stains (brown stain, blue stain, colored sapwood spots)
Grade B (I)
Chemical stains (brown stain, blue stain, colored sapwood spots)
Allowed up to 30% of the sheet surface
Grade S (I)
Chemical stains (brown stain, blue stain, colored sapwood spots)
Allowed up to 30% of the sheet surface
Grade BB+ (II)
Chemical stains (brown stain, blue stain, colored sapwood spots)
Allowed up to 20% of the sheet surface
Grade BB (II)
Chemical stains (brown stain, blue stain, colored sapwood spots)
Allowed up to 50% of the sheet surface (with false heart)
Grade CP (III)
Chemical stains (brown stain, blue stain, colored sapwood spots)
Allowed
Grade C (IV)
Chemical stains (brown stain, blue stain, colored sapwood spots)
Allowed
14. Discoloration with partial damage to the integrity of the wood integrity (rotting):
Grade B (I)
Discoloration with partial damage to the integrity of the wood integrity (rotting):
—
Grade S (I)
Discoloration with partial damage to the integrity of the wood integrity (rotting):
—
Grade BB+ (II)
Discoloration with partial damage to the integrity of the wood integrity (rotting):
—
Grade BB (II)
Discoloration with partial damage to the integrity of the wood integrity (rotting):
—
Grade CP (III)
Discoloration with partial damage to the integrity of the wood integrity (rotting):
—
Grade C (IV)
Discoloration with partial damage to the integrity of the wood integrity (rotting):
—
- without damage to the grain integrity;
Grade B (I)
- without damage to the grain integrity;
Not allowed
Grade S (I)
- without damage to the grain integrity;
Not allowed
Grade BB+ (II)
- without damage to the grain integrity;
Not allowed
Grade BB (II)
- without damage to the grain integrity;
Not allowed
Grade CP (III)
- without damage to the grain integrity;
Allowed
Grade C (IV)
- without damage to the grain integrity;
Allowed
- with damage to the grain integrity
Grade B (I)
- with damage to the grain integrity
Not allowed
Grade S (I)
- with damage to the grain integrity
Not allowed
Grade BB+ (II)
- with damage to the grain integrity
Not allowed
Grade BB (II)
- with damage to the grain integrity
Not allowed
Grade CP (III)
- with damage to the grain integrity
Not allowed
Grade C (IV)
- with damage to the grain integrity
Not allowed
15. Biological damage (wormhole)
Grade B (I)
Biological damage (wormhole)
Allowed in general quantity and with standards for black knots
Grade S (I)
Biological damage (wormhole)
Allowed in general quantity and with standards for black knots
Grade BB+ (II)
Biological damage (wormhole)
Allowed in general quantity and with standards for black knots
Grade BB (II)
Biological damage (wormhole)
Allowed in general quantity and with standards for black knots
Grade CP (III)
Biological damage (wormhole)
Allowed in general quantity and with standards for black knots
Grade C (IV)
Biological damage (wormhole)
Allowed in general quantity and with standards for black knots
16. Bark patch
Grade B (I)
Bark patch
Not allowed
Grade S (I)
Bark patch
Not allowed
Grade BB+ (II)
Bark patch
Not allowed
Grade BB (II)
Bark patch
Not allowed
Grade CP (III)
Bark patch
Not allowed
Grade C (IV)
Bark patch
Not allowed
17. Breaking out of grain
Grade B (I)
Breaking out of grain
Not allowed
Grade S (I)
Breaking out of grain
Not allowed
Grade BB+ (II)
Breaking out of grain
Not allowed
Grade BB (II)
Breaking out of grain
Allowed up to 5% of the sheet surface
Grade CP (III)
Breaking out of grain
Allowed up to 15% of the sheet surface
Grade C (IV)
Breaking out of grain
Allowed
18. Insert of wood for knotting
Grade B (I)
Insert of wood for knotting
Not allowed
Grade S (I)
Insert of wood for knotting
Allowed up to 1 piece per m2
Grade BB+ (II)
Insert of wood for knotting
Allowed up to 4 pieces per m2
Grade BB (II)
Insert of wood for knotting
Allowed up to 8 pieces per m2
Grade CP (III)
Insert of wood for knotting
Allowed
Grade C (IV)
Insert of wood for knotting
Allowed
19. Double insert
Grade B (I)
Double insert
Not allowed
Grade S (I)
Double insert
Not allowed
Grade BB+ (II)
Double insert
Not allowed
Grade BB (II)
Double insert
Allowed up to 1 piece per m2
Grade CP (III)
Double insert
Allowed
Grade C (IV)
Double insert
Allowed
20. Fallen-out insert
Grade B (I)
Fallen-out insert
Not allowed
Grade S (I)
Fallen-out insert
Not allowed
Grade BB+ (II)
Fallen-out insert
Not allowed
Grade BB (II)
Fallen-out insert
Not allowed
Grade CP (III)
Fallen-out insert
Not allowed
Grade C (IV)
Fallen-out insert
Allowed up to 2 pieces per m2
21. Filling of cracks Note: filling of cracks with putties or inserts – to be agreed with the customer
Grade B (I)
Filling of cracks Note: filling of cracks with putties or inserts – to be agreed with the customer
Not allowed
Grade S (I)
Filling of cracks Note: filling of cracks with putties or inserts – to be agreed with the customer
Not allowed
Grade BB+ (II)
Filling of cracks Note: filling of cracks with putties or inserts – to be agreed with the customer
Not allowed
Grade BB (II)
Filling of cracks Note: filling of cracks with putties or inserts – to be agreed with the customer
Cracks opened over 2 mm in width to be sealed with adhesive veneer inserts
Grade CP (III)
Filling of cracks Note: filling of cracks with putties or inserts – to be agreed with the customer
Cracks opened over 5 mm in width to be sealed with adhesive veneer inserts
Grade C (IV)
Filling of cracks Note: filling of cracks with putties or inserts – to be agreed with the customer
Allowed
22. Marks from caul plates (marks from pressing plates)
Grade B (I)
Marks from caul plates (marks from pressing plates)
Not allowed
Grade S (I)
Marks from caul plates (marks from pressing plates)
Not allowed
Grade BB+ (II)
Marks from caul plates (marks from pressing plates)
Allowed up to 100 mm in length and 2 mm in width of up to 1 piece per 1 m of sheet width
Grade BB (II)
Marks from caul plates (marks from pressing plates)
Allowed up to 100 mm in length and 2 mm in width of up to 1 piece per 1 m of sheet width
Grade CP (III)
Marks from caul plates (marks from pressing plates)
Allowed up to 300 mm in length and 2 mm in width of up to 2 pieces per 1 m of sheet width
Grade C (IV)
Marks from caul plates (marks from pressing plates)
Allowed
23. Veneer gap, edge defects due to trimming and sanding
Grade B (I)
Veneer gap, edge defects due to trimming and sanding
Allowed up to 2 mm in width along the edge
Grade S (I)
Veneer gap, edge defects due to trimming and sanding
Allowed up to 2 mm in width along the edge
Grade BB+ (II)
Veneer gap, edge defects due to trimming and sanding
Allowed up to 2 mm in width along the edge
Grade BB (II)
Veneer gap, edge defects due to trimming and sanding
Allowed up to 2 mm in width along the edge
Grade CP (III)
Veneer gap, edge defects due to trimming and sanding
Allowed up to 2 mm in width along the edge
Grade C (IV)
Veneer gap, edge defects due to trimming and sanding
Allowed up to 2 mm in width along the edge
24. Industrial stains (traces of beams, streaks)
Grade B (I)
Industrial stains (traces of beams, streaks)
Not allowed
Grade S (I)
Industrial stains (traces of beams, streaks)
Not allowed
Grade BB+ (II)
Industrial stains (traces of beams, streaks)
Allowed up to 15% of the sheet surface
Grade BB (II)
Industrial stains (traces of beams, streaks)
Allowed up to 15% of the sheet surface
Grade CP (III)
Industrial stains (traces of beams, streaks)
Allowed
Grade C (IV)
Industrial stains (traces of beams, streaks)
Allowed
25. Glue stain
Grade B (I)
Glue stain
Not allowed
Grade S (I)
Glue stain
Allowed up to 1% of the sheet surface
Grade BB+ (II)
Glue stain
Allowed up to 2% of the sheet surface
Grade BB (II)
Glue stain
—
Grade CP (III)
Glue stain
Allowed up to 5% of the sheet surface
Grade C (IV)
Glue stain
Allowed
26. Mechanical damage
Grade B (I)
Mechanical damage
Allowed in general quantity and with standards for black knots
Grade S (I)
Mechanical damage
Allowed in general quantity and with standards for black knots
Grade BB+ (II)
Mechanical damage
Allowed in general quantity and with standards for black knots
Grade BB (II)
Mechanical damage
Allowed in general quantity and with standards for black knots
Grade CP (III)
Mechanical damage
Allowed in general quantity and with standards for black knots
Grade C (IV)
Mechanical damage
Allowed in general quantity and with standards for black knots
27. Scratches, scars, pimples, hollow, crests
Grade B (I)
Scratches, scars, pimples, hollow, crests
Not allowed
Grade S (I)
Scratches, scars, pimples, hollow, crests
Not allowed
Grade BB+ (II)
Scratches, scars, pimples, hollow, crests
Allowed within the thickness tolerance values
Grade BB (II)
Scratches, scars, pimples, hollow, crests
Allowed within the thickness tolerance values
Grade CP (III)
Scratches, scars, pimples, hollow, crests
—
Grade C (IV)
Scratches, scars, pimples, hollow, crests
Allowed
28. Pocket (without bark inclusion)
Grade B (I)
Pocket (without bark inclusion)
Not allowed
Grade S (I)
Pocket (without bark inclusion)
Not allowed
Grade BB+ (II)
Pocket (without bark inclusion)
Not allowed
Grade BB (II)
Pocket (without bark inclusion)
Allowed
Grade CP (III)
Pocket (without bark inclusion)
Allowed
Grade C (IV)
Pocket (without bark inclusion)
Allowed
29. Warping
Grade B (I)
Warping
Ignored in plywood up to 6.5 mm thick, allowed in plywood over 6.5 mm thick for up to 15 mm per 1 m of the diagonal length of the plywood sheet
Grade S (I)
Warping
Ignored in plywood up to 6.5 mm thick, allowed in plywood over 6.5 mm thick for up to 15 mm per 1 m of the diagonal length of the plywood sheet
Grade BB+ (II)
Warping
Ignored in plywood up to 6.5 mm thick, allowed in plywood over 6.5 mm thick for up to 15 mm per 1 m of the diagonal length of the plywood sheet
Grade BB (II)
Warping
Ignored in plywood up to 6.5 mm thick, allowed in plywood over 6.5 mm thick for up to 15 mm per 1 m of the diagonal length of the plywood sheet
Grade CP (III)
Warping
Ignored in plywood up to 6.5 mm thick, allowed in plywood over 6.5 mm thick for up to 15 mm per 1 m of the diagonal length of the plywood sheet
Grade C (IV)
Warping
Ignored in plywood up to 6.5 mm thick, allowed in plywood over 6.5 mm thick for up to 15 mm per 1 m of the diagonal length of the plywood sheet
30. Blisters, delamination
Grade B (I)
Blisters, delamination
Not allowed
Grade S (I)
Blisters, delamination
Not allowed
Grade BB+ (II)
Blisters, delamination
Not allowed
Grade BB (II)
Blisters, delamination
Not allowed
Grade CP (III)
Blisters, delamination
Not allowed
Grade C (IV)
Blisters, delamination
Not allowed
31. Over-sanding
Grade B (I)
Over-sanding
Not allowed
Grade S (I)
Over-sanding
Not allowed
Grade BB+ (II)
Over-sanding
Not allowed
Grade BB (II)
Over-sanding
Not allowed
Grade CP (III)
Over-sanding
Allowed up to 1% of the sheet surface (for thickness from 3 to 21 mm). Allowed up to 2% of the sheet surface (for thickness of 24 mm and more)
Grade C (IV)
Over-sanding
Allowed
32. Under-sanding
Grade B (I)
Under-sanding
Not allowed
Grade S (I)
Under-sanding
Not allowed
Grade BB+ (II)
Under-sanding
Allowed 5 mm
Grade BB (II)
Under-sanding
Allowed 5 mm
Grade CP (III)
Under-sanding
Allowed up to 5 mm of the sheet surface
Grade C (IV)
Under-sanding
Allowed up to 50 mm of the sheet surface
33. Waviness (for sanded plywood), fuzziness, ripple
Grade B (I)
Waviness (for sanded plywood), fuzziness, ripple
Not allowed
Grade S (I)
Waviness (for sanded plywood), fuzziness, ripple
Not allowed
Grade BB+ (II)
Waviness (for sanded plywood), fuzziness, ripple
Not allowed
Grade BB (II)
Waviness (for sanded plywood), fuzziness, ripple
Not allowed
Grade CP (III)
Waviness (for sanded plywood), fuzziness, ripple
Allowed
Grade C (IV)
Waviness (for sanded plywood), fuzziness, ripple
Allowed
34. Plywood roughness
Grade B (I)
Plywood roughness
Roughness parameter Rmax according to GOST 7016, μm, up to: for sanded birch plywood − 100, for unsanded - 200
Grade S (I)
Plywood roughness
Roughness parameter Rmax according to GOST 7016, μm, up to: for sanded birch plywood − 100, for unsanded - 201
Grade BB+ (II)
Plywood roughness
Roughness parameter Rmax according to GOST 7016, μm, up to: for sanded birch plywood − 100, for unsanded - 202
Grade BB (II)
Plywood roughness
Roughness parameter Rmax according to GOST 7016, μm, up to: for sanded birch plywood − 100, for unsanded - 202
Grade CP (III)
Plywood roughness
Roughness parameter Rmax according to GOST 7016, μm, up to: for sanded birch plywood − 100, for unsanded - 202
Grade C (IV)
Plywood roughness
Roughness parameter Rmax according to GOST 7016, μm, up to: for sanded birch plywood − 100, for unsanded - 202
35. Veneer particles pasted
Grade B (I)
Veneer particles pasted
Not allowed
Grade S (I)
Veneer particles pasted
Not allowed
Grade BB+ (II)
Veneer particles pasted
Not allowed
Grade BB (II)
Veneer particles pasted
Allowed up to 150 mm in length and up to 30 mm in an width for up to 1 piece per sheet
Grade CP (III)
Veneer particles pasted
Allowed up to 150 mm in length and up to 30 mm in an width for up to 1 piece per sheet
Grade C (IV)
Veneer particles pasted
Allowed