Baltic Birch Plywood / Russian Birch Plywood GRADING RULES

Baltic Birch Plywood / Russian Birch Plywood GRADING RULES

INTERGOVERNMENTAL STANDARD
GOST 3916.1-96
Plywood with faces in hardwood veneer for general use.
Contents
 DESCRIPTION – GENERAL USE PLYWOOD
 CLASSIFICATION AND DIMENSIONS
 TECHNICAL REQUIREMENTS
 RULES OF ACCEPTANCE
 CONTROL METHODS
 TRANSPORTATION AND STORAGE
 PRODUCERS GUARANTEE
 Table: DESCRIPTION AND LIMITATIONS OF PLYWOOD DEFECTS
SPECIFICATIONS
Introduction date: 01-01-1998
1. DESCRIPTION – GENERAL USE PLYWOOD
This standard covers general use plywood with hardwood face veneer.
This standard is not applicable to specialty or decorative plywood.
Minimal requirements relating to the formaldehyde emission of plywood are covered in 4.3 and 6.8.
3. CLASSIFICATION AND DIMENSIONS
3.1. Plywood is subdivided into grades based on the following: appearance of face veneers, glue bond, the degree of moisture
resistance of the bond, and if sanded or not.
3.1.1. The plywood is subdivided into 5 grades, based on the appearance of the face veneers: E (elite), I, II, III and IV.
Descriptions of the face grades of the plywood are specified in Supplement A.
3.1.2. The degree of moisture resistance of the plywood bond is specified by the following marks:
 FSF – water proof plywood (WBP)
 FK – water resistant plywood (MR)
3.1.3. The sanding if the plywood is specified as follows:
 Not sanded (NS)
 Sanded one side (S1)
 Sanded two sides (S2)
3.2. Dimensions.
3.2.1. The dimensions and the number of plies in the plywood sheets must correspond to tables 1 and 2.
Table 1. Dimensions (millimeters)
Lengt(width) of the plywood sheets Min(Max)Tolerance in mm
1200,1220,1250 +/- 3,0
1500,1525,1800,1830 +/- 4,0
2100,2135,2440,2500 +/- 4,0
2700,2745,3050,3600,3660 +/- 6,0
Note: Production of plywood is allowed in other dimensions corresponding with the terms of a contract.
Table 2. Thickness (millimeters)
Nominal
thickness of
plywood
Number of plies
Sanded Plywood
Tolerance
Min/Max(mm)
Sanded Plywood
Thickness
Variance(mm)
Unsanded
Plywood
Tolerance
Min/Max (mm)
Unsanded
Plywood
Thickness
Variance(mm)
3,0 mm 3-ply + 0,3/-0,4 + 0,4/-0,3
4,0 mm 3-ply + 0,3/-0,5 + 0,8/-0,4
6,5 mm 5-ply + 0,4/-0,5 + 0,9/-0,4 1,0
9,0 mm 7-ply + 0,4/-0,6 + 1,0/-0,5
12,0 mm 9-ply + 0,5/-0,7 0,6 + 1,1/-0,6
15,0 mm 11-ply + 0,6/-0,8 + 1,2/-0,7
18,0 mm 13-ply + 0,7/-0,9 + 1,3/-0,8
21,0 mm 15-ply + 0,8/-1,0 + 1,4/-0,9 1,5
24,0 mm 17-ply + 0,9/-1,1 + 1,5/-1,0
27,0 mm 19-ply + 1,0/-1,2 1,0 + 1,6/-1,1 2,0
30,0 mm 21-ply + 1,1/-1,3 + 1,7/-1,2
Note: Production of plywood is allowed in other thickness and construction (number of plies) corresponding with the terms of
a contract. The minimum and maximum variances may be determined by the following formula.
Sanded Plywood – maximum/minimum tolerance:
1. Maximum: Thick * 0.03 mm + 0.2 mm (12 mm*0.03 mm + 0.2 mm) = 12 mm + 0.5 mm
2. Minimum: Thick * 0.03 mm + 0.4 mm (12 mm*0.03 mm + 0.4 mm) = 12 mm – 0.7 mm
Unsanded Plywood – maximum/minimum tolerance:
1. Maximum: Thick * 0.03 mm + 0.8 mm (12 mm*0.03 mm + 0.8 mm) = 12 mm + 1.1 mm
2. Minimum: Thick * 0.03 mm + 0.4 mm (12 mm*0.03 mm + 0.3 mm) = 12 mm – 0.6 mm
3.2.2. Plywood panels must be cut at a right angle. Deviation must not exceed 2 mm per 1 lineal meter.
3.2.3. Deviation from square edges can not exceed 2mm per 1 lineal meter.
3.3. Making if plywood must include:
 Name of product
 Woos species of the face and core veneers
 Glue Bond marks
 Veneer grades for face and core
 Formaldehyde emission classification
 Type of surface treatment
 Dimensions
 Applicable GOST standard
Below is an example of markings in plywood. Birch plywood with core plies of birch veneer, water resistant, with a
combination of face and core veneers I/III, with an emission class of E1, sanded in both sides, in 2440 mm long, 1220 mm
wide and 9 mm thick is marked:
Birch plywood/birch, FK, I/III, E1, S2, 2440*1220*9 GOST 3916.1-96
4.TECHNICAL REQUIREMENTS
4.1. Characteristics
4.1.1. To produce face veneers for plywood, the following species can be used for the face veneer: birch, alder, maple, elm,
beech, asp, poplar, lime. For core veneers, in addition to the ones just mentioned, the following can be used: pine, spruce, fir,
larch and cedar.
The timber used to make veneers fir plywood determines the species of the plywood.
The plywood can be made of one or more than one species of wood, therefore it is either “homogeneous” or “combined”.
If the number of veneer plies is even, the direction of fibers (grain) of the two middle plies must be parallel.
Veneers, located symmetrically within the thickness of plywood, must be the same species and thickness.
The thickness of the veneer used for the faces must not exceed 3,5 mm. And for the thickness if core veneers must nit exceed 4
mm.
4.1.2. Wood and manufacturing defects exceeding limits stated in Table 3, are not allowed in face veneers.
4.1.3. Wood and manufacturing defects, exceeding the limits stated in Table 3, are allowed in core veneers, as long as they do
not influence its integrity and dimensions. The requirements for quality and dimensions are specified in this standard.
4.1.4. The maximum amount of wood and manufacturing defects allowed in face veneers is indicated in Table 4.
4.1.5. The combination of face veneer grades is indicated in GOST 30427.
4.1.6. The face veneer of E grade can consist of 2 components with one splice joint in the middle of the panel. This applies
only to widths up to 1525 mm.
If the width is over 1525 mm, the face veneer if E grade can consist of 3 components of equal width. The face veneer of I and
II grades can be made from an unlimited number of veneer components.
For grades E, I, II veneer joints must be parallel to plywood edges. Veneers must be matched for color.
4.1.7. Plugs must be even with the surface, firmly bonded, must match the color of the face of the panel. The grain must also
be parallel to the direction of the wood fibers (grain) on face veneer. For grades I and II the plugs must match the color of the
wood.
Putty fills or reapirs must match the color of the wood of a given grade. In addition, they must provide easy gluing, retain its
color during plywood treatment and not crack while bending.
4.2. Strength and mechanical indices are stated in Table 5.
4.3. Formaldehyde content in plywood, depending in emission class, must meet the limits stated in Table 6.
4.4. The plywood is measured in either square meters or cubic meters. The volume of one panel is determined with a precision
of up to 0.00001 m3. The volume of a few panels is determined with the precision of up to 0.5 m3. The squareness of a panel is
measured with the precision of up to 0.01 m2. The squareness of a few panels in measured with a precision of up to 0.5 m2.
4.5. The marking is stamped with indelible paint on the back side of every panel stating plywood grade and inspector’s number.
Marks of bundles or crates of plywood contain:
 Name if the country plywood-producer
 Name of mill-producer or its trade mark
 Conventional plywood marking
 Number of panels in the bundle
 National mark of conformity for certified production
 Transportation marking is in accordance with GOST 14192.
4.6. Packaging.
4.6.1. Plywood must be packed in bundles weighting no more than 1500 kgs. It has to be separated according to species, glue
bond, grades, glue emission classes, types of surface treatments and dimensions.
If parties mutually agree and in accordance with a sales contract, plywood can be packed in bundles or other weights.
4.6.2. If plywood id to be shipped to regions in the extreme north or other difficult-to-reach regions, it has to be packed
according to 4.6.1. and GOST 15848.
5. RULES OF ACCEPTANCE
5.1. Plywood is accepted in lots.
A lot consists of plywood of one species, one glue bond, one sort, one glue emission class one type of surface treatment and
panel dimensions.
There should be one document for each lot, specifying quality and containing:
 Name of the country-producer
 Name of the mill-producer and (or) its trade mark
 Conventional plywood marking
 Volume or square meters of panels in lot
 Stamp of technical control
 National mark of conformity for a certified production
5.2. Quality and dimensions of panels are subject to random inspection. If specified in a sales contract (agreement), specific
lots may be subject to full inspection.
In a random inspection, sheets are selected indiscriminately in accordance with GOST 18324 and confirming the quantities,
mentioned in Table 7.
5.3. Shear, tensile and static bending strengths are checked fir plywood of every species, glue bond and number of plies at least
once month. In accordance with sales contracts (agreements), it is permitted to select 0.1 % of sheets in every lot, but not less
than one sheet.
5.4. Formaldehyde emission is checked every 30 days for FSF plywood mark and every 15 days for FK plywood mark. In
accordance with terms of sales contract, a check may be done every 7 days.
5.5. A lot is considered to meet the requirement of the current standard and is accepted, if in the random inspection the
following is confirmed:
 number of plywood sheets which are not meeting the requirements of the current standard due to dimensions, out of square,
linear edges, wood and manufacturing defects is LESS or EQUAL to the accepted amount, which is stated in Table 7.
 all sheets of plywood must have no bubbles, no delamination and no trace of bark
 formaldehyde emission corresponds to the norms defined in Table 6
6. CONTROL METHODS
6.1. Selection of samples for strength and mechanical tests are done in accordance with GOST 9620. Selection of samples for
formaldehyde emission tests are done in accordance with GOST 27678.
6.2. The length and width is measured at two points in the same panel, which are parallel to the edges and are located at least
100 mm from the edges. The measurements are done with a metal tape, which has an index error of 1 mm or less in accordance
with GOST 7502. Measurements have to be taken twice and the actual length (width) of the sheet would be their average.
6.3. Thickness is measured at a distance of at least 100 mm from the edges. Thickness also has to be measured at the middle of
each side of the panel with a caliper as per GOST 11358, or with a micrometer with a scale division of at least 0.1 mm in
accordance with GOST 6507.
Measurements of thickness have to be taken 4 times and the actual thickness would be an average of those 4 measurements.
The difference in thickness in one panel of plywood is determined as a difference between the maximum and minimum
thickness from these 4 measurements.
6.4. Moisture content is determined in accordance with GOST 9621.
6.5. Shear strength along the glue line is determined in accordance with GOST 9624.
6.6. Static bending strength is determined in accordance with GOST 9625
6.7. Tensile strength is determined in accordance with GOST 9662
6.8. Formaldehyde emission is determined in accordance with GOST 27678
6.9. Roughness of the surface is determined in accordance with GOST 15612
6.10. Wood and manufacturing defects are measured in accordance with GOST 30427
6.11. Deviation from linear edges of plywood panel is determined by measurements of the maximum gap between the panel
edge and metallic square edge in accordance with GOST 8925 and within an index error of 0,2 mm.
6.12. Measurements for squareness are determined in accordance with GOST 30427.
7. TRANSPORTATION AND STORAGE
7.1. Plywood is transported in covered vehicles, in accordance with the transportation consignment rules for each given
vehicle.
7.2. Transportation and storage of plywood, which is to be shipped to the Extreme North or difficult-to-access regions are done
in accordance with GOST 15846.
7.3. Plywood is stored in horizontally stacked bundles, on pallets or on wooden pallets. The temperature of closed premises, in
which the plywood is stored, should be between -40 C to +50 C. The humidity should not exceed 80 %.
8. PRODUCERS GUARANTEE
Producers guarantee that the plywood conforms with the current GOST, as well as with transportation and storage conditions.
FK plywood has a guarantee of 3 years and FSF plywood has a guarantee of 5 years from the day it was shipped.
TABLE 3. DESCRIPTION AND LIMITATIONS OF PLYWOOD DEFECTS
Description of defects
as per GOST 30427
E grade
plywood face
veneers
I grade
plywood face
veneers
II grade
plywood face
veneers
III grade
plywood face
veneers
IV grade
plywood face
veneers
1.Pin knots Not allowed Max. 3 per M2
allowed Allowed Allowed Allowed
2.Sound lights and/or
dark knots Not allowed
Up to 5 per M2
max, 15mm
diam. cracks no
more than
0,5mm wide
Up to 10 per M2
max, 25mm
diam. cracks no
more than 1mm
wide
Allow cracks not
more than
1,5mm wide
Allow cracks not
more than
1,5mm wide
3.Loose knots or
with/without knot
holes, worn holes in
cluster or scattered
Not allowed Up to 3 with max
6 mm diam.
Up to 6 with max
6 mm diam.
Up to 6 with max
6 mm diam.
No limits with
max 40 mm
diam.
4.Tight cracks/splits Not allowed
Up to 2 per 1M
of plywood, max
200mm long
Up to 2 per 1M
of plywood, max
200mm long
Allowed Allowed
5.Wide cracks/splits Not allowed Not allowed
Up to 2 per 1M
of plywood filled
with putty max
200mm long
Up to 2 per 1M
of plywood filled
with putty max
600mm long and
5 mm wide
Allowed with
limitations
6.Light Mold Not allowed Allowed Allowed Allowed Allowed
7.Dark mold Not allowed Not allowed
General number
allowed as per
item 2 of present
table
General number
allowed as per
item 2 of present
table
Allowed
8.Deviation in wood
structure
Allowed very
insignificant,
incidental
disposition
Allowed Allowed Allowed Allowed
9.Light color variation Not allowed
Allowed, no
more than 5% of
the sheet surface
Allowed Allowed Allowed
10.Strong color
variation Not allowed Not allowed Not allowed Not allowed Allowed
11.Decay Not allowed Not allowed Not allowed Not allowed Not allowed
12.Pinholes Not allowed
General number
allowed as per
item 3 of present
table
General number
allowed as per
item 3 of present
table
General number
allowed as per
item 3 of present
table
General number
allowed as per
item 3 of present
table
13.Veneer overlap Not allowed Not allowed
Allowed no more
than 100mm in
quantity of no
more than 1
piece for 1m of
panel width
Allowed no more
than 200mm in
quantity of no
more than 2
pieces for 1m of
panel width
Allowed
14.Lack of veneer,
defects of panel edges
due to sanding or
squaring
Not allowed
Allowed with a
width of no more
than 2mm
Allowed with a
width of no more
than 4mm
Allowed with a
width of no more
than 4mm
Allowed with a
width of no more
than 5mm
15.Presense of glue tape Not allowed Not allowed Allowed in non- Allowed in non- Allowed in non-
sanded plywood sanded plywood sanded plywood
16.Glue bleed through Not allowed Not allowed
Allowed no more
than 2% of panel
surface
Allowed no more
than 5% of panel
surface
Allowed
17.Scratches Not allowed Not allowed Allowed Allowed Allowed
18.Indentations or
imprints Not allowed Not allowed
Allowed if
depth/height is in
range of
thickness
variance
Allowed if
depth/height is in
range of
thickness
variance
Allowed
19.Torn Grain, Brashy
Fibers Not allowed Not allowed
Allowed no more
than 5% of panel
surface
Allowed no more
than 15% of
panel surface
Allowed
20.Grinding Not allowed Not allowed Not allowed Not allowed Allowed
21.Warp and twist
Does not apply
to thickness
under 6,5mm. If
over 6,5mm then
allowed with sag
of no more than
15mm over 1M
panel’s diagonal
length
Does not apply
to thickness
under 6,5mm. If
over 6,5mm then
allowed with sag
of no more than
15mm over 1M
panel’s diagonal
length
Does not apply
to thickness
under 6,5mm. If
over 6,5mm then
allowed with sag
of no more than
15mm over 1M
panel’s diagonal
length
Does not apply
to thickness
under 6,5mm. If
over 6,5mm then
allowed with sag
of no more than
15mm over 1M
panel’s diagonal
length
Does not apply
to thickness
under 6,5mm. If
over 6,5mm then
allowed with sag
of no more than
15mm over 1M
panel’s diagonal
length
22.Metal inclusions Not allowed Not allowed Not allowed
Color metal
staples are
allowed
Color metal
staples are
allowed
23.Gap in slice joint Not allowed Not allowed
Allowed with
width of no more
than 1mm in 1
piece for 1M of
panel sheet
Allowed with
width of no more
than 2 mm in 1
piece for 1M of
panel sheet
Allowed
24.Delamination,
bubbles, etc Not allowed Not allowed Not allowed Not allowed Not allowed
25.Waviness(for sanded
plywood), charter
marks
Not allowed Not allowed Not allowed Allowed Allowed
26.Rough or torn grain
Roughness
parameter(Rm)
is per GOST
7016; 100 for
sanded plywood
and 200 for nonsanded
Roughness
parameter(Rm)
is per GOST
7016; 100 for
sanded plywood
and 200 for nonsanded
Roughness
parameter(Rm)
is per GOST
7016; 100 for
sanded plywood
and 200 for nonsanded
Roughness
parameter(Rm)
is per GOST
7016; 100 for
sanded plywood
and 200 for nonsanded
Roughness
parameter(Rm)
is per GOST
7016; 100 for
sanded plywood
and 200 for nonsanded
27.Wooden plugs Not allowed Not allowed
Allowed in
repair up to 8
pieces for 1m2
of panel
Allowed with no
limits
Allowed with no
limits
28.Overlapped plugs Not allowed Not allowed
Allowed no more
than 2 pieces per
1m2 of panel
Allowed Allowed
Note:
 1. Norm of manufacturing defects “lack of veneer” refers both to outer and core lines.
 2. Wood and manufacturing defects which are not mentioned in Table 3 are not allowed.
TABLE 4
Grade of Face Veneer Maximum amount of permitted defects for wood and manufacturing (in pieces)
E No visible defects
I 3
II 6
III 9
IV Amount of wood and manufacturing defects is unlimited. Limits on dimensions is in
accordance with items 3,5,11,12,14,24 of Table 3
APPENDIX A
COMPARATIVE CHART OF GRADE MARKING IN THIS GOST,
IN GOST 10.55-71 AND GOST 3916.1-89 GRADES
GOST 3916.1-96 GOST 10.55-71 GOST 3916.1-89
E – A
I B AB
II BB B
III CP BB
IV C C
TABLE 5
Index Thickness
(mm)
Glue
bond Birch Alder
Beech
Pine Larch
Fir Silverfir
Cedar
Lime Asp
Poplar
Moisure content 3-30 FSF
FK 5-10 5-10 5-10 5-10
Shear strenght (MPa) not less than
after boiling in water
for 1 hour 3-30
FSF 1,5 1,2 1,0 0,6
after soaking in water
for 24 hours FK 1,5 1,0 1,0 0,6
Static bending strength
of fibres (MPa) not less
than
9-30
FSF 60 50 40 30
FK 55,0 45,0 35,0 25,0
Tensile strengh along
fibers, MPa, no less
than
3-6,5
FSF 40,0 40,0 40,0 40,0
FK 30,0 30,0 30,0 30,0
Note: Shear strength along glue line of 1.2. Mpa is permitted in accordance with terms of a sales contract.
TABLE 6
Glue Emission Class Formaldehyde content in 100 grams of dry plywood mass, in mg.
E1 Up to 10
E2 From 10 to 30
TABLE 7
Volume for the lot
Index of control on the items below(in panels)
3.2.1.; 3.2.3; 3.2.3; 4.1.2; 4.1.6; 4.1.7; 4.3
Selection Volume Number for Acceptance Selection Volume Number for Acceptance
Up to 500 8 1 13 1
501 to 1200 13 1 20 2
1201 to 3200 13 1 32 3
3201 to 10000 20 2 32 3

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