Plywood Standard GBT 9846-2015

 Range of nominal thickness(t)

Unsanded board

Sanded board(surface)

Common difference of inner thickness

Difference of nominal thickness

Common difference of inner thickness

Difference of nominal thickness

t≤3

0.5

+0.4

-0.2

0.3

±0.2

3＜t≤7

0.7

+0.5

-0.3

0.5

±0.3

7＜t≤12

1.0

+(0.8+0.03t)

-(0.4+0.03t)

0.6

+（0.2+0.03t）

-（0,4+0.03t）

12＜t≤25

1.5

0.6

+(0.2+0.03t)

-(0.3+0.03t)

t＞25

0.8

Defects type

Item

Surface

Back face

Superior

First-class

Qualified

Pin holes

—

Allowed

Intergrown knot

Maximum single diameter/mm

10

20

Unlimited

Partiqlly intergrown knot, dead knot, bark pocket

Total number on 1m2's surface

Not allowed

4

6

Unlimited

Partiqlly intergrown knot

Maximum single diameter/mm

Not allowed

15(if the number ≤5, it shall be ignored)

Unlimited

Dead knot

Maximum single diameter/mm

Not allowed

4   (if the number ≤2, it shall be ignored)

15

Unlimited

Bark pocket

Single maximum length/mm

Not allowed

20(if the number ≤5, it shall be ignored)

Unlimited

Abnormal structure of wood

—

Allowed

 Cracks

Single maximum width/mm

Not allowed

1.5

for linden 0.5

3，

for linden1.5，

for wood from south China 4

6

Single maximum length/mm

200

wood from South China 250

400

for wood from south China 450

800

for wood from south China 1000

 Worm holes、dog holes, holes

Maximum single diameter/mm

Not allowed

4

8

15

Total number on 1m2's surface

4

Sieve pores are not allowed

 Discoloration

Shall not exceed % the area of board

Not allowed

30

Unlimited

Note 1：Streaks with light color shall be seen as color variation.

Note 2: For class 1 products, the width of streaks with deep color shall not exceed 2mm, and the length shall not exceed 20mm.

Note 3:For birch products,except for superior products, false heartwood is allowed, but the gloss of first-class products shall be harmonious.

Note 4: For first class birch products, dense brown or black pith flecks are not allowed.

Note 5: Sapwood and heartwood with different colors shall be seen as a case of color variation.

Decay

—

Not allowed

Initial decay is allowed if the strength is not influenced, but the area shall not

 exceed 1% of the board area.

Initial decay is allowed

Gum duct

Single maximum length/mm

Not allowed

150

Unlimited

Single maximum width/mm

10

Total number on 1m2's surface

4

Assembled gap on the surface

Single maximum width/mm

Not allowed

0.5

1

2

The single maximum length is % the length of board

10

30

50

Total number within a width of 1m

1

2

Unlimited

 Folded layers

Single maximum width/mm

Not allowed

8

10

The single maximum width is % the width of board

20

Unlimited

 Core gaps and overlaps

Core gaps and overlaps stick closely to the surface board

Single maximum width/mm

Not allowed

2

6

8

Total number within a width of 1m

2

Unlimited

Maximum gap width in other layers

8

—

gaps and overlaps of cross-band veneer

Single maximum width/mm

Not allowed

8

—

 Blistering、layering

—

Not allowed

—

 Dents,press marks，blisering

maximum area/mm2

Not allowed

50

400

Unlimited

Total number on 1m2's surface

1

4

 Burrs

shall not exceed % the the area of board

Not allowed

1

2

Unlimited

the depth shall not exceed/mm

0.2

Penetration is not allowed

The surface is sanded through

Total number on 1m2's surface

Not allowed

400

Unlimited

Glue penetration and other man-made contamination

Shall not exceed % the area of board

Not allowed

0.5

30

Unlimited

Repair patch, repair strip

Allowable number for well-made, firmly repaired ones

Not allowed

3

Unlimited

Unlimited

The cumulative area shall not exceed % the area of board

0.5

3

The crack shall not be longer than/mm

0.5

1

2

Include aluminum-made staple

—

  Not allowed

—

Deformity on the edge

within nominal size, shall not exceed /mm

 Not allowed

10

Other defects

—

Not allowed

Count them as their most similar defect types

Defects type

Item

Surface

Back face

Superior

First-class

Qualified

Pin holes

—

Allowed

Intergrown knots,partially intergrown knot, dead knot, bark pocket

Total number on 1m2's surface

5

8

10

Unlimited

Intergrown knot

Maximum single diameter/mm

20

30,(if the number ≤10, it shall be ignored)

Unlimited

Partially intergrown knot，dead knot

Maximum single diameter/mm

5(if the number ≤2, it shall be ignored)

30(if the number ≤10, it shall be ignored)

Unlimited

Abnormal structure of wood

—

Allowed

Bark pocket、resin pocket

Total number on 1m2's surface

3

4

(if the number ≤10,

it shall be ignored)

10

(if the number ≤15, 

it shall be ignored)

Unlimited

Single maximum length/mm

15

30

Unlimited

Cracks

Maximum single width/mm

Not allowed

1

2

6

Single maximum length/mm

200

400

1000

Wormholes, dogholes

Maximum single diameter/mm

Not allowed

2

10

15

Total number on 1m2's surface

4

10( if the number ≤3, it shall be ignored)

Sieve pores are not allowed

Color variation

shall not exceed % the the area of board

Not allowed

Light color 10

Not allowed

Decay

—

Not allowed

1%, Initial decay is allowed if the strength 

is not influenced, but the area shall not 

exceed 1% of the board area.

Initial decay is allowed

Resinous wood（resinous streak)

Single maximum length/mm

Not allowed

150

Unlimited

Maximum single width/mm

10

Total number on 1m2's surface

4

Assembled gap on the surface

Single maximum width/mm

Not allowed

0.5

1

2

The single maximum length is % the length of board

10

30

50

Total number within a width of 1m

1

2

Unlimited

Folded layers

Single maximum width/mm

Not allowed

2

10

 The single maximum width is % the width of board

20

Unlimited

Core gaps and overlaps

Core gaps and overlaps stick closely to the surface board

Single maximum width/mm

Not allowed

2

4

8

Total number within a width of 1m

2

Unlimited

Maximum gap width in other layers

8

—

Gaps and overlaps of cross-band veneer

Single maximum width/mm

Not allowed

8

—

Blistering、layering

—

Not allowed

—

Dents,press marks，blisering

Single maximum area/mm2

Not allowed

50

400

Unlimited

Total number on 1m2's surface

2

6

Burrs

shall not exceed % the the area of board

Not allowed

5

20

 Unlimited

the depth shall not exceed/mm

0.5

Penetration is not allowed

The surface is sanded through

Total number on 1m2's surface

Not allowed

400

Unlimited

Glue penetration and other man-made contamination

Shall not exceed % the area of board

Not allowed

1

Unlimited

Repair patch, repair strip

Allowable number for well-made, firmly repaired ones

 Not allowed

6

Unlimited

The cumulative area shall not exceed % the area of board

1

5

Unlimited

The crack shall not be longer than/mm

0.5

1

2

Include aluminum-made staple

—

Not allowed

—

Deformity on the edge

within nominal size, shall not exceed /mm

 Not allowed

10

Other defects

—

Not allowed

Count them as their most similar defect types

Defects type

Item

Surface

Back face

Superior

First-class

Qualified

Pin holes

—

Allowed

Intergrown knot

Maximum single diameter/mm

10

20

Unlimited

Partially intergrown knot, dead knot, bark pocket

Total number on 1m2's surface

Not allowed

3

5

Unlimited

Partially intergrown knot

Maximum single diameter/mm

10,if the number ≤5, it shall be ignored)

Unlimited

Dead knot

Maximum single diameter/mm

4(if the number ≤2, it shall be ignored)

15

Unlimited

Abnormal structure of wood

—

Allowed

Cracks

Single maximum width/mm

Not allowed

1.2

2

6

Single maximum length/mm

250

350

800

Bark pocket

Total number on 1m2's surface

Not allowed

2

4

Unlimited

Single maximum length/mm

10(if the number ≤5, it shall be ignored)

Unlimited

Worm problems

Worm holes

Total number on 1m2's surface

Not allowed

8(if  ≤1.5mm, it shall be ignored)

8

15

Single maximum diameter/mm

2

 Sieve pores are not allowed

Worm ducts

Total number on 1m2's surface

Not allowed

2

Single maximum length/mm

10

Dog holes， holes

Single maximum diameter/mm

Not allowed

2

8

15

Total number on 1m2's surface

1

Unlimited

Discoloration

Shall not exceed % the area of board

Not allowed

5

Unlimited

Decay

—

Not allowed

1%

Initial decay is allowed if the strength is not influenced, but the area shall not exceed 1% of the board area.

Initial decay is allowed

Gum duct

Single maximum length/mm

Not allowed

150

Unlimited

Single maximum width/mm

10

Total number on 1m2's surface

4

Assembled gap on the surface

Single maximum width/mm

Not allowed

1

2

The single maximum length is % the length of board

30

50

Total number within a width of 1m

2

Unlimited

Folded layers

Single maximum width/mm

Not allowed

2

10

 The single maximum width is % the width of board

20

Unlimited

Core gaps and overlaps

Core gaps and overlaps stick closely to the surface board

Single maximum width/mm

Not allowed

2

4

8

Total number within a width of 1m

2

Unlimited

Maximum gap width in other layers

Not allowed

8

—

Gaps and overlaps of cross-band veneer

Single maximum width/mm

Not allowed

8

—

Blistering、layering

—

Not allowed

—

Dents, indentations, drums

Total number on 1m2's surface

Not allowed

1

4

Unlimited

Burrs

shall not exceed % the the area of board

Not allowed

1

25

Unlimited

Maximum depth

0.4

Penetration is not allowed

The surface is sanded through

Total number on 1m2's surface

 Not allowed

400

Unlimited

Glue penetration and other man-made contamination

Shall not exceed % the area of board

Not allowed

0.5

30

Unlimited

Repair patch, repair strip

Allowable number for well-made, firmly repaired ones

Not allowed

3

Unlimited

Unlimited

The cumulative area shall not exceed % the area of board

0.5

3

The crack shall not be longer than/mm

0.5

1

2

Include aluminum-made staple

—

 Not allowed

—

Deformity on the edge

within nominal size, shall not exceed /mm

 Not allowed

10

(24)Other defects

—

Not allowed

Count them as their most similar defect types

Wood variety of plywood

Category

I、II Category

III Category

Hardwoods(include tropical hardwoods

5~14

5~16

Coniferous wood

Category I: The ones which can past boiling test and can be used in outdoor environment.

Category II：The ones which can past 63℃±3℃ hot water dipping test, can be made into wet conditions as moisture-resistant plywood.

Category III:The ones which can past 20℃±3℃ cold water dipping test, can be made into dry conditions as moisture-prone plywood.

Tree variety/Wood name/Name of foreign commercial goods

Category

I,II category

III category

Basswood, cypress, sample, paulownia wood, rubber wood, meranti, Okoume, white wutong, Anisoptera spp, Calophyllum inophyllum, eucalyptus wood

≥0.70

≥0.70

Northeast China ash, lotus wood, sweetgum, maple wood, elm, Chinese oak, apitong, cloning, kapur

≥0.80

Birch

≥1.00

Pinus massoniana, yunnan pine pine, larch, spruce, monterey pine

≥0.80