How Strong Is Plywood to make furniture? | Plywood Strength Comparison with Other Wood Products

How Strong Is Plywood? 

Plywood is a strong material, to understand why you have to look at the way it is made.

 

This is an Engineered Wood product, joining multiple thin layers of veneers together.

Joining - pressure-bonded with adhesives, at varying angles

Veneers > its produced from wood logs using "rotary cut" or "slicing" methods. This rotary cutting method is used commonly. It works by rotating the log of wood around its longitudinal axis using machines and peeling the layers of the logwood using cutting tools.

 

At least 3 such wooden veneers are Joined together on each sheet of plywood.

What is Plywood and How is it Made?

What makes plywood so strong to make furniture?

The way each of these layers (veneer) is stacked on top of each other. Each individual layer (veneer) has a grain shape, meaning that it is easy to tear the veneer across the grain but not across it. This uniqueness is used for maximum benefit when creating plywood sheets. The layers are arranged one on top of the other so that the grain shapes are alternately always perpendicular to each other.

Plywood has a high strength to weight ratio, which means it is relatively lightweight but durable. This makes it easier to carry than other materials such as solid wood or steel.

 

 

What determines the strength of the plywood?

Quality of wood used

The most important factor affecting the strength of plywood is the type of wood used in its manufacture. Hardwood (e.g. teak or kurgan wood) is better in quality and stronger than softwood (e.g. pine wood or mango wood).

Therefore, plywood sheets made using good quality hardwood are stronger than those made using softwood.

 

The thickness of the sheet

Plywood is Made in a different range of sizes and thicknesses. The general rule of thumb is that the increase of the sheet thickness will increase the sheet strength and also say the thicker sheets also cost more.

 

Quality checks for strengths

Some of the quality tests carried out are mentioned below.

Moisture content (percentage)	Moisture in plywood can affect its strength. If the content is too low, the plywood sheet will be too dry and therefore fragile. On the other hand, if the moisture is too high, the board is prone to rot and decay. Moisture content Should be between 5% and 15%
Glue shear strength	Glue or bonding material measures the stability of holding veneer layers/piles together.
Water-resistance test	Checks resistance to water. For BWR grades, samples are submerged in boiling water for upto 72 hours.
Screw and Nail Holding strength	The ability of the plywood to hold on to nails and screws
Modulus of elasticity	Is measured across the face grain as well as along the face grain
Modulus of rupture	Is measured along and across the grain
Mycological test	To check the resistance against micro-organisms such as fungi

 

Many tests are performed on the plywood, such as measuring specific gravity, tensile strength, compressive strength, as well as water absorption.

 

Plywood Strength Comparison with Other Wood Products

 

Plywood Vs Particle Board, LDF and MDF

Particleboard is made from wood chips/flakes and Low (LDF) and Medium (MDF) Density Fibreboard is made from wood fibres) therefore plywood is much stronger than this engineered wood.

If you've ever looked closely at furniture made of chipboard or MDF, you must have noticed that instead of nails, the fitting is all done using screws, and that's because the holding strength of these woods is very poor.

The ability of the plywood to hold on to nails and screws is high

 

Plywood Vs Block boards

Plywood is stronger than the blockboards. Both manufacturing methods are similar. (Blockboards have a core made of softwood blocks and are glued to both sides of the plywood. Solid-core flush doors are very similar).

Article: Plywood vs Blockboard - Which to choose for your Furniture and Budget? | Lceted

However, in some cases where bookshelves or fixtures longer than 6 or 7 feet need to be used, blockboards are preferred over plywood. This is because the plywood will bend or sag in the middle when using its long pieces.

 

Plywood Vs solid wood

Among carpenters is that solid wood is better compared to wood because it is a homogeneous material and therefore there is no question of splitting layers, unlike plywood. Solid wood is therefore generally considered to be harder than plywood, although the strength of solid wood depends on the quality and purpose

Another advantage of solid natural wood over plywood is that it is more natural and does not contain chemical resins (glues). Solid wood (obtained from the hardwood of good quality such as teakwood) is generally preferred over plywood, although it is much more expensive in its pure form.

 

Also Read: Woodworking Materials Guide for Beginners! | Woodworking Handbook