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What is a plywood board?
A plywood board is formed by the sum of several wood veneers placed one on top of another with the direction of opposing grains and joined by synthetic glue and a high-pressure machine. It is also known as plywood or laminated wood.
Typically, plywood boards are 2500mm long and 1200mm wide and the thickness can vary depending on their final application. If the board is thicker, it will need a greater number of veneers to achieve the desired result. They can be made out of different types of wood, such as the Paulownia, poplar, or okoume board.
Plywood is used because it is more robust, solid and resistant board than the same thickness other solid wood. The fact that this boar wood is as robust and resistant comes from the nature of formation of its layers. The grains of each layer goes in a different direction than the other.
What is a phenolic plywood board?
It is a plywood board with the difference that the glue used to join the sheets is rich in formaldehyde which makes it last much longer against rot and humidity. It is a board widely used in marine environments.
How is a plywood board made?
Once we have the selected logs from which we want to obtain the wood veneer, we proceed to remove the bark from the trunk. This process will leave the trunk with a straight part where the blade will then begin to remove sheets of wood.
Then it is time to put the logs in the steam engines to soften the wood a bit. The time invested in this process will vary depending on the density of the wood. Once the logs have the adequate humidity, it is time to obtain the veneers.
The question of how to make a plywood board starts by putting a log in a machine that spins it while a blade peels it, leaving a 0.6 mm thick veneer (Similar process when we peel an apple, this method is called peeling veneer).
Then the veneer is cut every 1200 mm. After this process the veneers are dried in the open air or in wood dryers (similar to stoves).
When the veneers have around 11% humidity, the process of repairing the damages in certain sheets or wood veneers is carried out.
The second step involves the process of putting the boards together.
We put one sheet on top of another, always with the grains in the opposite direction to the previous one and always after each veneer a layer of synthetic glue.
Afterwards, a lot of pressure is applied for 40 minutes at high temperatures to set the veneers. The last process is to cut the remaining sides for making the board straight on all 4 sides.
What Tool Is Used To Obtain The Plywood Sheets?
In both the unrolling method and the flat method a knife is used. The difference is that in unwinding it is the tree that rotates and in the flat method the trunk is fixed and it is the blade that moves back and forth.
The history of plywood begins much earlier than we might imagine. The first items discovered were plywood boards made out of solid woods in ancient Egypt, around 3500 B.C. This solution of transversely joined veneers was made due to the lack of quality woods in the area. Thus, they obtained a product of better quality and resistance with a poor wood substrate.
Another historical antecedent, a little closer in time, is the one found in of the shields of the Roman army (scutum).This shield was formed by a plywood made with the woods found in the area, that is the reason why the tools used by the Romans varied depending on the type of trees there were close.
In the 18th and 19th centuries we can find examples of plywood in high-quality English furniture. But the great revolution in plywood came with the invention of the revolving lathe for obtaining veneer by Emmanuel Nobel (1801-1872). In the middle of the 19th century the first machine was installed in the United States. From that moment on, the production of plywood increased.
Pictures of a Plywood Board
Uses and Types of Plywood
A plywood board has myriad uses due to its characteristics, depending on the glue used in the board, it will have some uses or others.
This is a plywood board formed with a glue or resin of urea-formaldehyde, which is light in colour. They are used for interior furniture or interior panels. It allows uses with certain degree of humidity.
Outdoor Plywood Or Phenolic WPB
These boards are manufactured with a dark colored phenolic adhesive. They can be used in environments totally or partially exposed to the weather conditions, as long as they do not have a construction use.
Marine Plywood Board
It is a high quality phenolic plywood, which as its name suggests, it is used in the maritime sector. Since exposure to saltpeter and humidity greatly affects the wood, the highest wood quality is needed for this domain. It is a board where the veneers do not have any damage and are glued with a strong phenolic adhesive. Also, for the last veneers a noble wood such as mahogany is used, this is translated in an increase of the price of the plywood.
This type of plywood board is not widely used in Spain or in Europe, it is very popular in the United States to build houses. In contraposition with the Maritime ones, the species used are of a much lower quality.
Classification of Plywood According to its Adhesive
Laminate boards or LVL = Laminated Veneer Lumber or plywood are classified as follows:
- Dry environment.
- Humid environment
- Outdoor environment
Or through this list
- Structural LVL / 1 in dry environment
- Structural LVL / 2 in humid environment
- Structural LVL / 3 in outdoor environment
What are the most commonly used woods to make plywood boards?
- Red oak
- Lauan (Philippine mahogany)
Paulownia Plywood Board
This type of plywood is widely used in Japan for the automotive industry or for premium furniture. Its use is not common in Europe and the only company that manufactures them is GREEMAP. Thanks to the fact that paulownia is a light wood, (270 kg / m3). That is why paulownia plywood board is the lightest in the world. It is a board that has incredible potential for shipbuilding, aerospace or for the automotive sector where lightness is rewarded.
Origins of Paulownia Plywood
Because the wood is indigenous to Southeast Asia, paulownia plywood also comes from there, specifically from China and Japan.
It has an average density of 270 Kg / m3 for a moisture content of 12%.
The characteristics of paulownia plywood has a static bending strength of 243 kg / cm³. As for the modulus of elasticity, it is 24,915 kg / cm². Its resistance to axial compression is 126 kg / cm². These tests have been carried out by GREEMAP in the INCAFUST wood laboratory.
The length can be from 100mm to 2500mm and the width from 100mm to 1200mm, as for the thickness it can be from 3mm to 27mm.
Paulownia Plywood Datasheet
Below you can download the GREEMAP paulownia plywood technical datasheet by clicking on the following link.
Where to Buy Paulownia Plywood Board?
Paulownia plywood is a new product in Europe, GREEMAP is the only European producer of this type of laminated wood.