In typical furniture like in cupboards or storage units, we have two parts: one is a Frame (or shelf, carcass, or boxes), and the second is Shutters (Doors, slides)
One is fixed and another one is opening or closing either on hinges or sliding channels.
So, in the typical choice of boards, we have two choices, Plywood and blockboards.
Let us understand the property of each one of these:
In the case of plywood or blockboard, both use wood derivatives.
Plywood: for manufacturing plywood, timber is sliced into wooden veneers ranging from 1.5mm to 3mm depending upon need/quality, and these veneers are known as core veneers. These veneers are joined together to get the desired thickness, for typical 18mm plywood we may need 7-12 layers of core veneers. These veneers may not be in the size of 8ft * 4 ft (a typical size of plywood), and there can be joints horizontally also. Further surface of these veneers may not be smooth and there may be knots, so to give a better finish, on top of it a thin layer of veneer is added (typically 0.2mm to 0.4mm), this is known as face veneer. This face veneer can be of various grades (A/B/C/D) or different names to suggest the quality of face veneers.
All the layers of the Veneer (Face and core) are joined together with glue. These glues can be Melamine, Urea or phenolic, or a combination of these.
To make plywood stronger and free from wood borer or termites, some chemicals are also added.
So now we understand that plywood is a composition of wood, chemicals, and glue.
Many attributes decide the quality of the boards, such as; water resistance property, termite & borer resistance property, surface quality, thickness variation/calibration property, screw holding capacity, load bearing capacity, bending property, surface texture, routing property, gap between layers (core gap), density of the boards, emission from the boards, fire resistance, bonding of the boards, elasticity of the boards.
And the combination of these determines the life of the plywood and furniture.
Those major parts of plywood are independent of each other like the core, Face, Glue, and chemicals.
Any quality of wood species (core) can be combined with any face or treated with any kind of glue or chemicals.
For use purposes, plywood is categorized as Packing grade, Commercial grade, interior furniture grade, Exterior furniture grade, and marine grade & fire retardant.
There is more to be learned in upcoming writeups
Blockboard
We have seen that in plywood thin layers of wood veneers are joined together to get desired strength.
However in the case of block boards, strips of wood, also known as lumber strips are joined together side by side.
The thickness of the lumber strips decides the thickness of the boards.
Typical construction is like:
Center: strips of wood
Front and back: core veneers, MDF, or HDF
And on the surface finish: face veneer (optional)
The center of the board is always strips of wood joint horizontally to get the desired width of the board, typically 4ft, and joined vertically to get the length of the board, typically 8 ft. thickness of the board is adjusted to get the desired thickness of the board. A frame is made using these strips. Now this frame is bonded/joined in various ways such as glue, wire, and stapler. This frame is made in such a way that there is no gap between strips either horizontal or vertical.
The front and back layers typically use wooden veneers in the thickness range of 1.5mm to 2.5mm on both sides. However nowadays, a thin layer of MDF (medium-density fiberboard) or HDF (high-density fiberboard) is also used instead of a thin layer of wooden veneer, this is done for a better surface finish (we know that the surface of MDF is smoother than wooden veneer)
Face veneer: As we know core veneer as added to the front and back does not have a better surface finish, so a face veneer is added to get the best surface finish. However, this is not required if MDF / HDF is used in place of plywood core veneer.
So typical construction will be like this:
Front and back: either (core veneer + face veneer) or only MDF / HDF
Center: solid wooden cores. (however many other types of fillers are used for doors, which we will learn later)
Suppose the board thickness is 19mm, and the core veneer + face put together is 1.5mm, and this is applied on both sides (front and back), that means the front and back is 3mm, so the frame thickness need to be 16mm.
Once the frame is done, the front and back are ready and they will be joined together through glue application and will be pressed together: construction will be like this:
Face veneer + core veneer + solid wood strip frame + core veneer + face veneer
Now we understand that the major components are:
A> Wooden components:
Solid wood: softwood/ hardwood
Core veneer
Face veneers
B> Non wooden components: Chemical & glue.
We will understand more about quality & variants of the block boards in coming writeups.