Birch Plywood is subdivided by different grades depending on face veneer quality. Plywood grade is marked by face and back veneer quality (face/back).
For example:
В/ВB (I/II), BB/BB (II/II), BB/CP (II/III), BB/C (II/IV), CP/CP (III/III), CP/C (III/IV), C/C (IV/IV)
Grade "E" (Elite)
Perfect grade
The highest quality grade is „E“ (Elite). Almost without any defects. This plywood is an exclusive material used in high class design projects.
| Categories of defects | Permissible amount of defects |
| Pine knots | Permitted |
| Irregularities in the structure of wood | Permitted, but slight |
| Coloured streaks | Permitted accosionally |
Grade "B" ( I )
Grade „B“ birch plywood is almost without deffects. Allowed are several pin knots and single sound tight knots. The plywood sheet has beautiful natural woodden texture.
„B“ grade plywood is Intended for natural finish. The material is suitable for covering with laquer and paint.
„B“ grade plywood is widely used for furniture production, wall panels and creation of decorative elements in interior design.
| Categories of defects | Permissible amount of defects |
|---|---|
| Pin knots | Permitted up to 3 per 1 m² |
| Other knots and patched holes:
sound knots |
Permitted up to an individual maximum diameter of 15 mm in amount of 5 per 1 m² |
| unsound (falling) knots | Permitted up to an individual maximum diameter of 6 mm in amount of 3 per 1 m² |
| Knots and knotholes repairement | Not Permitted |
| Irregularities in the structure of wood | Permitted |
| Hearth and discoloration | Not more than 5% of surface |
| Closed splits and checks, patched | Permitted for an individual maximum length up to 200 mm in amount of 2 per 1 m width of sheet |
| Closed splits and checks, patched | Permitted for an individual maximum length up to 200 mm in amount of 2 per 1 m width of sheet |
| Open splits | Not Permitted |
| Discolouration and coloured streaks | Permitted, but slight |
| Defects at the edges due to sanding or sawing | Allowed up to 2 mm from the edge |
| Glue penetration | Not Permitted |
| Sanding through | Not Permitted |
Grade "S"
Grade „S“ plywood is almost without defects. Occasional small sound tight knots are allowed and up to 2 patches are allowed per m2.
Grade „S“ plywood is used for varnishing and painting in furniture construction, decoration and lamination with various kind of wood.
| Categories of defects | Permissible amount of defects |
|---|---|
| Pin knots | Permitted (diameter to 3mm) |
| Sound intergrown knots light/dark | “Allowed up to an individual maximum diameter of 20 mm with total quantity not more than 2,5 per m2 (or total diameter up to 50mm/m2 of the panel square) 0,5” |
| Partly intergrown, open knots, knotholes, worm tracks | Allowed up to an individual maximum diameter of 10 mm with total quantity not more than 2,5 per m2 (or total diameter up to 25mm/m2 of the panel square) 0,5 |
| Knots and knotholes repairement | Not Permitted |
| Irregularities in the structure of wood | Permitted |
| Hearth and discoloration | Not more than 5% of surface |
| Closed splits and checks, patched | Permitted for an individual maximum length up to 200 mm in amount of 2 per 1 m width of sheet |
| Defects at the edges due to sanding or sawing | Allowed up to 5 mm from the edge |
| Glue penetration | Allowed not more than, 1% of the panel surface |
| Sanding through | Not Permitted |
Grade "BB" ( II )
Grade „BB“ allows pin knots, some sound tight knots and also up to 8 plug repairs per m2 on plywood sheet surface.
The direction of plug repair’s wood grain complies with general direction of wood grain of entire plywood sheet, which makes plug repairs less visible.
Grade „BB“ plywood is widely used for furniture production and can be covered with different decorative materials.
| Categories of defects | Permissible amount of defects |
|---|---|
| Pin knots | Permitted |
| Sound knots | Permitted up to an individual maximum diameter of 25 mm in amount of 10 per 1 m² |
| Other knots and patched holes: unsound (falling) knots |
Permitted up to an individual maximum diameter of 6 mm in amount of 6 per 1 m² |
| Irregularities in the structure of wood | Permitted, but slight |
| Open splits and patched holes | Permitted for an individual maximum length up to 200 mm and width up to 2 mm in amount of 2 per 1 m width of sheet |
| Closed splits and checks, patched | Permitted for an individual maximum length up to 200 mm in amount of 2 per 1 m width of sheet |
| Discolouration and coloured streaks | Not more than 30% of surface |
| Repaired defects (inserts) | Permitted up to 8 per m² |
| Double inserts | Not Permitted |
| Sanding through | Not allowed |
| Glue penetration | Permitted up to 2% of surface |
| Defects on the edges due to sanding or sawing | Admitted up to 5 mm from the edge |
Grade "CP" (III)
Grade „CP“ allows more defects on the surface of the plywood sheet. Sound knots and plug repairs are allowed without limitations in quantity. Repairs with putty are allowed.
Grade „CP“ is suitable for construction purposes: for such applications where plywood shall not be observed and for special packaging.
Plywood calibration allows to use this plywood grade for laminating of plywood sheet with valuable veneer.
| Categories of defects | Permissible amount of defects |
|---|---|
| Pin knots | Permitted |
| Sound knots | Permitted along with cracks for width up to 1,5 mm |
| Other knots and patched holes | Permitted up to an individual maximum diameter of 6 mm in amount of 10 per 1 m² |
| Repaired defects (inserts) | Allowed |
| Double inserts | Allowed |
| Irregularities in the structure of the wood | Allowed |
| Discolouration and coloured streaks | Permitted |
| Avatud läbivad lõhed | Lubatud maksimum pikkusega kuni 300 mm ja laiusega kuni 5 mm koguses kuni 5tk/m plaadi pikkuse kohta |
| Open splits | Permitted for an individual maximum length up to 300 mm and width up to 5 mm in amount of 5 per 1 m length of sheet |
| Closed splits and checks | Permitted |
| Open joints, patched | Permitted for an individual maximum width up to 2 mm and length of 200 mm, no more than 1 per metre of sheet width |
| Overlaps | Permitted for a maximum length of 200 mm and no more than 1 per metre of sheet width |
| Hollows, bumps and imprints | Permitted, but slight |
| Roughness | Permitted, but slight |
| Inserts | Unlimited number permitted |
| Sanding through | Permitted up to an extent of 10 cm² |
| Glue penetration | Permitted up to an extent of 5% of the surface of sheet |
| Defects on the edges due to sanding or sawing | Admitted up to 4 mm from the edge |
Grade "WG"
Grade „WG“ is one position lower than grade CP. Grade „WG“ allows slightly bigger knots (in diameter) and edges defects than CP grade.
Grade „WG“ is suitable for using in construction, where plywood is not observed and for special packaging.
| Categories of defects | Permissible amount of defects |
|---|---|
| Sound intergrown knots | Allowed up to an individual maximum diameter of 65 mm |
| Other knots and knot holes | Allowed up to an individual maximum diameter of 15 mm with total quantity not more than 10 per m2 |
| Repaired defects (inserts) | Allowed |
| Double inserts | Allowed |
| Irregularities in the structure of the wood | Allowed |
| Open splits | Permitted for an individual maximum length up to 300 mm and width up to 4 mm in amount of 2 per 1 m length of sheet |
| Closed splits | Permitted |
| Hearth and discoloration | Permitted |
| Open joints, patched | Permitted for an individual maximum width up to 2 mm and length of 200 mm, no more than 1 per metre of sheet width |
| Overlaps | Permitted |
| Hollows, bumps and imprints | Permitted, but slight |
| Inserts | Unlimited number permitted |
| Sanding through | Permitted up to 5% of surface |
| Glue penetration | Permitted up to an extent of 5% of the surface of sheet |
| Defects on the edges due to sanding or sawing | Admitted up to 5 mm from the edge |
Grade "C" (IV)
Grade „C“ plywood has the lowest surface quality, which doesn’t affect however durability of the material.
Grade „C“ plywood sheet is unsanded. The manufacturing standard allows all defects including knot holes. Plywood has good gluing.
Grade „C“ plywood is widely used upholstered furniture production. Also for production of packages packaging and for building constructions that are not observed.
| Categories of defects | Permissible amount of defects |
|---|---|
| Pin knots | Permitted |
| Sound knots | Permitted |
| Other knots: unsound knots |
Permitted up to an individual maximum diameter of 40 mm in unlimited amount |
| Discolouration and coloured streaks | Permitted |
| Open splits and checks | Permitted for an individual maximum width up to 10 mm in unlimited length and amount |
| Closed splits and checks | Permitted |
| Open joints | Permitted for an individual maximum width up to 3 mm |
| Overlap | Permitted for a maximum length of 500 mm and no more than 2 per metre of sheet width |
| Hollows, bumps and imprints | Permitted, some |
| Roughness | Permitted |
| Inserts | Unlimited number permitted |
| Glue penetration | Permitted |
| Defects on the edges due to sawing | Admitted up to 5 mm from the edge |
