International Plywood Standards

       ◆  BSI ◆  HPVA
       ◆  JPIC  SFS   
       ◆  CE     

British Standards Institution

1.Defects Of Plywood
Table 1. Defects inherent in wood
Category Type
1 Pin knots  
2 Sound intergrown knots with a diameter greater than 3 mm  
3 Partially intergrown knots, unsound knots and non-adhering knots; also holes due to bores and parasitic plants

1 Partially adhering or intergrown knots
2 Non-adhering knots
3 Knots holes
4 Dog holes

4 Irregularities in the structure of the wood

1 Angle grain
2 Curly grain including burls
3 Interlocked grain
4 Spiral grain
5 Short grain

5 Splits
    Checks
1 Open
2 Closed
6 Bark pockets, resin pockets and resin streaks
1 Open
2 Closed
7 Defects due to borers, vines and parasitic plants

1 Small worm holes( pinworm holes)
2 Large worm holes and worm channels
3 Marine Borer holes
4 Marks of vines or parasitic plants
5 Chicken track

8 Sound discoloration

1 Blue stain
2 Colored sap stains
3 False heartwood
4 Other discoloration such as chemical stain and color streaks
5 Mould

9 Rot  
NOTE. Defects and characteristics inherent in wood are defined in BS 6566: Part 2.
 
Table 2. Manufacturing defects
Category Type
10 Open joints  
11 Overlaps and pleats on the surface  
12 Blisters

 

13 Hollows
    Imprints
    Bumps
 
14 Roughness  
15 Sanding through  
16 Glue penetration

 

17 Inclusion of metal partial (see note 2)

 

18 Repairs

1 Patches
2 Shims
3 Synthetic filling

19 Defects at the edges of the panel

1 Sanding defects
2 Sawing defects

20 Other defects  
NOTE. 1. Manufacturing defects are defined in BS 6566: Part 2.
NOTE. 2. It should be noted that 'ferrous'  metal particles are prohibited in all grades in plywood.
 
2 Requirements for tolerances on dimensions of plywood

2.1 Compliance
When tested in accordance with appendix A, the plywood shall comply with 2.2 to 2.6.
2.2 Thickness
The deviation between the mean thickness and the nominal thickness and the maximum difference in thickness measurements within the panel shall be within the tolerance.
2.3 Edge straightness
The deviation in edge straightness shall not exceed +/- 1mm per meter length of the panel being assessed.
2.4 Squareness
The out of squareness of the edge of the panel shall not exceed +/-1.5mm per meter of the edge of the panel being assessed. It shall be permissible to determine this by measurement of diagonals, but these differ by more than 0.25%, where there is doubt about the validity of the diagonal measuring method, e.g. when the shorter edges of the panel incline to or away from the center by a similar amount, and in case of dispute, the try-square method shall be employed.
2.5 Length and width
The tolerances on the nominal length and width of a panel shall be within +0, -4mm for the modular range (see appendix B) and within +/-4mm for other sizes.
NOTE. Panels for some special end user may have tolerance different from those specified in this clause.
2.6 Flatness
This standard does not specify a requirement for flatness.
NOTE. The amount of distortion that can be tolerated will depend not only on the thickness of the panel, the construction and the species but also on the requirements of the end user.

 
Table 1. Thickness tolerances for veneer plywood within outer plies of coniferous species
Maximum deviations permitted between the mean thickness of a panel and its nominal thickness. Maximum permitted difference between thickness measurements of an individual sample panel
Sanded
`
Unsanded
`
Sanded
Unsanded
Nominal thickness
Deviation
Nominal thickness
Deviation
mm
Up to and including 18
mm
+/-0.5
mm
Up to and including 20.5
mm
+1.0
-0.5
mm
mm
Over 18
+/-3% of t*
Above 20.5
+/-8% of t* -.05
0.8
1.5
*t is the nominal thickness (in mm).
NOTE. Tolerances for touch sanded plywood are not covered by this table.
 
Table 2. Thickness tolerances for veneer plywood with outer plies of broadleaved species and for core plywood
Maximum deviations permitted between the mean thickness of a panel and its nominal thickness. Maximum permitted difference between thickness measurements of an individual sample panel
Nominal thickness
Sanded
Unsanded
Nominal thickness
Sanded
Unsanded
mm
Up to and including 4
mm
+0.2
-0.4
mm
+0.8
mm
Up to and including 12
mm
0.4
mm
0.8
Over 4
+0.2
-(0.4+3% of t)*
-(0.3+3% of t)*
Over 12
0.6
1.0
*t is the nominal thickness (in mm).
 
3.Grade Of Plywood
(b) Grades B, BB and C*
No.
Categories of defectst 
Grade
B (face)
BB
C* (back)
1 Pin Knots Permitted if tight and not clustered permitted permitted
2 Sound intergrown knots exceeding 3 mm in diameter Four permitted per 3 square metres of the surface of the outer ply, to a maximum individual diameter of 13mm (not closed) Five permitted per 3 square metres of the surface of the outer ply, to a maximum individual diameter of 25mm permitted
3 Partially intergrown knots, unsound knots and nonadhering knots; also holes due to borers and parasitic plants Not permitted Permitted to a maximum individual diameter of 9mm, provided their cumulative diameter does not exceed 40mm per square metre and they are properly filled permitted
4 Irregularities in the structure of the wood: sound burls (curely grain) permitted if smooth permitted permitted
5 Splits      
(a) Open splits (puttied) Two permitted at each end of a panel, to a maximum individual width of 3mm and a maximum individual length of 6% of the panel length Two permitted at each end of a panel, to a maximum individual width of 5mm and a maximum individual length of 12.5% of the panel length Eight permitted at each end of a panel, to a maximum individual width of 15mm and a maximum individual length of 40% of the panel length
(b) Close splits (hairline) Three permitted per panel at the ends and to a maximum individual length of 100mm permitted permitted
(c) Compression failure (cross break) One permitted per outer ply provided hairline and of a length not exceeding 10% of the panel width One permitted per outer ply provided hairline and of a length not exceeding 10% of the panel width `
6 Bark pockets Not permitted Permitted if very slight permitted
Resin pockets Not permitted One permitted per square metre of the outer ply, to a maximum individual width of 4mm and to a maximum individual length of 100mm permitted
Resin exudation Not permitted permitted if slight permitted
7 Defects due to borers, vines and parasitic plants      
(a) Worm holes and channels Not permitted Pinworm holes permitted provided they are occasional, scattered and well puttied. No discoloration permitted. Worm channels not permitted. permitted
(b) Marks of parasite      
plants and vines Two permitted per outer ply, to a maximum individual width of 4mm and maximum individual length of 100mm, provided the are smoothly sanded and leveled permitted if occasional and smoothly sanded and levelled permitted
(c) Chicken track Permitted if isolated and slight permitted permitted
8 Sound discoloration (natural), stain/mineral streak Permitted if very slight Permitted if not excessive permitted
9 Rot Not permitted Not permitted Not permitted
10 Open joints Not permitted Three permitted per outer ply, to a maximum individual width of 3mm and to a maximum individual length of 10% of the panel length, if properly filled Permitted to a maximum individual width of 15mm and to a maximum individual length of 60% of the panel length
Mechanical defects, e.g. chainmarks, machinery stain, sander burns, metal stain, grease, oil or colored chalk on face Not permitted Permitted if slight and occasional permitted
14 Roughness, brashness or torn grain Permitted if very slight and occasional Permitted if slight Permitted if not excessive
17 Inclusion of metal particles Permitted if non-ferrous and in inner plies or cores only Permitted if non-ferrous and in inner plies or cores only Permitted if non-ferrous and in inner plies or cores only
Sanding Smooth Reasonably smooth No special requirements
18 Repairs, boat or symmetrical patch Not permitted Five permitted per outer ply, to a maximum individual width of 100mm and to a maximum individual length of 150mm, provided they are well made, are of similar grain and are color matched Permitted
  Shims Not permitted Permitted to a maximum individual width of 5mm and to a maximum individual length of 300mm, provided they are well made, are of similar grain and are color matched Permitted
  Tape or glue residue, putty mark Not permitted Permitted if slight and smoothly sanded Permitted
  Knifemark Not permitted Permitted to a width of 0.8mm if slight Permitted
20 Other defects which are not indicated Not permitted unless they resemble a defect already defined in which case they shall be considered under that category Not permitted unless they resemble a defect already defined in which case they shall be considered under that category Not permitted unless they resemble a defect already defined in which case they shall be considered under that category
*It is intended that classification by appearance of tropical hardwood plywood covered by this table will, in a reasonable time, comply with the grading requirements for grades ⃿⃿and ⃿given to the grade descriptions in table 6(a).
Numbers cross reference, where possible, to those in table 5,6(a) and 7.
Sometimes designated CC quality.

---------------------------------------------Quality Test: