The Guide of Plywood (Material,Making & Uses)

What is plywood?

Plywood is an engineered wood product, and has many varied applications. It is most commonly used for making the furniture that we use in our homes and offices, and also for other applications such as in building construction, and for doing the woodwork in boats and ships.

Composition of plywood:

Plywood is made from several thin layers of wooden veneers stacked over one another. These veneers, called plies, are firmly glued to each other so that they don’t come apart easily.

The number of plies in every plywood sheet is usually an odd number, such as 3-ply, 5-ply, 7-ply etc.

While stacking the veneers over one another, it is ensured that the grain direction of the plies in adjacent layers is perpendicular to each other. Because of this the plywood board becomes strong in both directions.

How plywood is made:

The veneers, which are thin slices of wood are obtained from logs of trees. The logs are mounted on a lathe machine, and are rotated about their longitudinal axis, while a cutter peels off thin layers from the log (Somewhat similar to the way we peel layers from vegetables).

Glue is applied to all these peeled slices of wood veneers (plies) using glue spreader machines, and the plies are placed one upon the other. The stack then goes into a hot press machine, which firmly presses the veneers together and forms a strong bond between the individual plies so that they do not come apart. Thus a plywood sheet or board is made.

Plywood Classification and Grading

There are two broad classes of plywood, each with its own grading system.

One class is known as construction and industrial. Plywood in this class are used primarily for their strength and are rated by their exposure capability and the grade of veneer used on the face and back. Exposure capability may be interior or exterior, depending on the type of glue. Veneer grades may be N, A, B, C, or D. N grade has very few surface defects, while D grade may have numerous knots and splits. For example, plywood used for sub flooring in a house and to making plywood doors is rated “Interior C-D”. This means it has a C face with a D back, and the glue is suitable for use in protected locations. The inner plies of all construction and industrial plywood are made from grade C or D veneer, no matter what the rating.

The other class of plywood is known as hardwood and decorative. Plywood in this class are used primarily for their appearance and are graded in descending order of resistance to moisture as Technical (Exterior), Type I (Exterior), Type II (Interior), and Type III (Interior). Their face veneers are virtually free of defects.

Ways of decorating plywood:

Unlike natural solid wood, plywood is not a very beautiful looking material. It is strong, but it usually needs to be decorated in some way or the other so that it looks good as well. The most common ways of decorating plywood are listed below.

Painting – This is one of the cheapest ways to decorate plywood. You can use any wood colour of your choice for this purpose.

Staining – This also adds colour to the plywood, but in a way that the underlying grain pattern can still be seen. Painting on the other hand forms a thicker coat that covers the plywood grain entirely.

Laminating – Decorative laminates can be glued over the plywood surface to make it look attractive. These decorative laminates are made from papers saturated with phenolic and melamine resins, and are hard, brittle, water-resistant and scratch-resistant. These decorative laminates are available in various shades, colours, designs, textures and patterns, and are the top choice for decorating plywood. Laminated plywood doors not only looks good, it also helps to protect and to increase the life of the plywood sheet.

Veneering – Very thin slices of veneers obtained from a better looking wood (e.g. teak, oak, maple, cherry wood etc.) can be glued over the faces of the plywood to make it look more beautiful. Good quality and rare wood veneers are however much costlier compared to decorative laminates.