Here are some simple ways to select and distinguish the quality of plywood:
First of all, the defects that are not allowed in any grade of plywood are opening glue (separation between plywood layers) and bubbling (flaky surface on the back board is not stuck to the core board, and therefore slightly puffed up). These two defects will directly affect the use of plywood.
1. Panel level
First of all, it is necessary to distinguish the panel grade of plywood.
China's plywood panels are divided into four grades, that is, first-class, second-class and third-class.
Premium plywood panels are almost free of defects (individual minor material defects are allowed);
First-class plywood panels are allowed to have individual minor defects (such as pin joints, dead joints, wormholes, cracks, depressions, indentations, etc.);
In addition to allowing a small number of minor defects, second-class plywood panels are also allowed to have individual slightly serious defects (such as patches, patches, plate edge defects);
Third class plywood panel allows more defects
If it is imported plywood, its grade standard can be graded according to China's plywood panel grade standard.
2. Flatness
a) Method:
<1> Sliding horizontally with your hand against the board, you can feel the flatness of the board;
<2> When looking at the plywood surface in the light, the flatness of the plywood can also be more obviously seen.
b) Identification:
High quality plywood, because of its good material, fine workmanship, the board surface will be very flat, feel smooth. Inferior plywood, because of its poor material, rough workmanship, internal stack from the core is serious, light can see the uneven surface of the board, feel convex and concave.
3. Core board quality
High quality plywood, the core board is the whole sheet, good quality, the joint between the core board is tight; When hitting the board, the sound is "crisp".
Inferior plywood, the core board is spliced by small core board, there are many wormholes and dead joints on the core board, the core board is large, and the stack from the core is serious; When hitting the board, the sound is "dull".
4. Strength
Lift one end of the plywood, shake a few times, if you feel the board is very solid, indicating its internal quality is good, high strength; If the board is "trembling", there is a creaking sound, indicating that the strength of the board is poor. The worst plywood or plywood with serious structural problems can even break due to violent shaking.
5. Thickness
High quality plywood, the thickness tolerance between the whole batch of boards is small, and the thickness of different parts of the single plywood is uniform;
Inferior plywood, the thickness tolerance between the whole batch of boards is large, the thickness of different parts of the sheet plywood is not uniform, and the thickness difference in different parts is even greater than 1mm (the current sander is good, and the thickness tolerance is generally very small).
6. Smell and environmental protection
If the board emits a pungent smell, it means that the environmental protection of the board is not up to standard; Environmentally friendly plywood emits the smell of the wood itself, which is not irritating. However, if you want to finally determine whether the plywood meets the environmental requirements, you must also ask a special wood-based panel testing agency to test.
