Friday, 28 July 2017

Types of plywood: A walkthrough

Plywood is a man-made replacement of wood which is extensively used in various applications. Plywood is well-known for its versatility in applications. Plywood is actually a laminated product made up of numerous thin wood strips laid alternatively and bonded using glue onto strong stable sheets. Due to this, the susceptibility of plywood to expansion and shrinkage due to moisture is extremely low. 
A plywood is made of odd number of layers called plies with equal number of plies sandwiched on each side of the center ply. This way, the center plies are always parallel and this kind of construction makes it a lot stronger than a board of equal thickness cut from a tree. Plywood is generally graded using letters A, B, C, and D, where A is the best quality with no blemishes and well sanded while grade D is the one with a lot of virtual blemishes. This means grade A is suitable for a finishing material while D grade plywood is not.

Plywood are generally graded in pairs. One side refers to the better side, which is called the face and acts as the finishing surface and the other side is the back side. For example, a plywood of grade A-C will have a well finished face and a relatively unfinished back of grade C.

There are 4 common types of plywood bonding types. These variations in glue types are used depending on what conditions the material will be subjected to after the installation is done. Based on this, there are 5 types of plywood:

  • Structural plywood: This is the type of plywood which is used when appearance is of no importance and stability and strength is the primary concern. It is commonly used in concrete forms at construction sites. The resins and binding glue used to join the plies are manufactured to provide extra strength make a structural plywood extra strong. This type of plywood is not aesthetically pleasing. It is generally of C-D grade.
  • Marine plywood: Marine plywood is exclusive designed for applications where there is a need of high moisture resistivity. The adhesives used in this type are of high quality which neither dissolve in water nor absorb moisture. It is hard and is suitable for all types of marine applications. As this is manufactured using hardwood and high-quality adhesives and has appealing finish as well, it is costlier than other types of plywood. It is generally of A-A grade.
  • Interior plywood: This type is made of various species of hardwood and softwood and used precisely as it name mentions - in interior applications like wall sheathing, furniture, cabinetry, etc. This type of plywood is available in many grades according to requirement but manly have one surface of grade A to get an attractive finish. There are species like birch, oak and cherry available for design purposes.
  • Exterior plywood: This is the most commonly sold plywood type at any home center. This type is more resistant to moisture than interior plywood as this is used for exterior used and is exposed to nature and is prone getting wet in rain. So, a little moisture resistivity is necessary. Similar to interior plywood, all types of grades are available in this type as well. The grades A-C, B-C, and CDX are the most common ones.
  • Sanded plywood: In case of making cabinets, one side has to be visually attractive as that will be visible on the external side of the cabinet, to the user. For such applications, sanded plywood is the best choice. This type is generally of A-C grade where one side is sanded and the interior side, which is not visible to the user is of lesser C grade.

You can choose the type of plywood according to your application needs and use it as a perfect replacement of wood. These customisable property of plywood is the reason it has become immensely popular. 

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