What is wood?

Wood is a strong porous fibrous material, which forms the outer layer of trees. The trunk and the bark of the trees are primarily used for wood making. The wood industry is responsible for the production of wood from forests. Trees are chopped down and made in the form of bars and planks which are known as timber or sometimes as lumber in North America. Wood is an example of natural composite material whose cellulose fibers are fused with lignin matrix, this provides better tensile and compressive strength to the wood.

There are different types of wood that have various uses. Among the different types of wood, hardwood has plenty of uses. These kinds of woods form the second choice of engineers as an important building material after concrete.
This article emphasizes outlining the different types of wood, their sources, and their uses.

Major sources of wood

We get wood from various forest trees and woody plants. They belong to the family of gymnosperms and angiosperms. Gymnosperms are cone-bearing trees, from which softwoods are obtained such as pine and spruce, whereas angiosperms are responsible for hardwoods such as oak, teak, and balsa wood.

Hardwood and Softwood

Hardwoods are obtained from flowering plants that form the family of angiosperms. These plants are characterized by broader leaves and they shed their leaves annually. These trees are evergreen, bigger in size, and grow at a slower pace. The xylem of these trees are responsible to carry water and nutrients, they are lined with lignin, which gives excessive hardness to the trees. Hardwood is extremely durable than softwood. They are mainly found in parts of the USA and Europe. Maple, sassafras, olive trees, walnut, cherry, ash, alder, cottonwood are examples of hardwood.

Hardwood has numerous uses in woodworking or commercial businesses such as fuel sources, tools, constructions, boat building, furniture making, musical instruments, cooking items, utensils, manufacturing of barrels, and so on. Mahogany was a popular red-brown hardwood, used by the Spanish and English for manufacturing ships and furniture. Mahogany is characterized by its rich, red timber. There are various species of mahogany such as Cuban mahogany, South American mahogany, Sapele, Honduran mahogany, and so on. White oak is another example of hardwood whose fibers are straight-grained and these trees usually have a long lifespan. Overexploitation of mahogany has limited the usability of such trees in the present century.

Softwood comes from conifers, they fall under the category of gymnosperms. As the term suggests, softwoods are not necessarily softer than hardwoods, as both these categories differ by densities and strength. For instance, Balsa is a kind of hardwood that is much softer than softwood. Softwoods are used in the paper industries that use pulp, primarily obtained from softwoods.

Softwoods are characterized by their yellowish-brown color. The trees of softwood have needle-shaped leaves and they account for more than 70% of the timber production than hardwood. Softwood is usually cheaper and widely used as a substitute for hardwoods, they are also lighter in weight. The grain pattern of such woods differ distinctly and are knotty.

Medium-density fiber (MDF) boards are the special class of engineered wood products, made by the combination of hardwood and softwood fibers with suitable wax and fibers. These types of wood products are very popular among many hobby computer numerical control (CNC) users and carpenters running small businesses.

Some popular woods used in different applications

Plywood

Plywood is referred to as an engineered wood, whose grain patterns are characterized by 90-degree orientation. Plywood is made by stacking multiple thin sheets of veneer. These veneer sheets are glued together through a suitable resin and are pressure-treated by mechanical or hydraulic presses. The veneer can be obtained by cutting the outer layer of trees into thin slices of approximately less than 3 mm. Plywood is a thick and flat wood product that does not undergo shrinkage and wrapping with time. There are multiple uses of plywood in the furniture industry and they are equally used in many woodworking applications as well.

Pinewood

Pinewood is one of the most popular woods used by many manufacturing industries and is majorly used in carpentry. Pinewood is obtained from pine trees which are coniferous and occur in the northern hemisphere and several parts of south-east Asia. Pinewood is regarded as the strongest softwood and hence they form a popular choice among the carpenters.

Cedarwood

Cedarwood is obtained from coniferous trees and is classified under the category of softwood. Cedar has good weather and moisture-resistant properties that make it suitable for exterior applications like siding, shingles, decking, greenhouse, arbors, and fences. Cedar also has better rot-resistant properties among other woods and its oils act as an excellent insect-repelling solution.

Context and Applications

This topic is majorly taught in many undergraduate, postgraduate, and diploma courses of:

• Bachelors of Technology (Civil engineering)
• Masters of Technology (Civil engineering)
• Masters in Science in Building materials
• Masters in Science in Wood technology

Practice Problems

Q 1. Which of the following wood is an insect-repellent?

1. Teak
2. White oak
3. Cedar wood
4. Read oak

Answer: Option c

Explanation: Cedar wood is an insect-repellent wood.

Q 2. Which of the following engineered wood makes use of mechanical press during its production?

a. MDF

b. Plywood

c. SPF Lumber

d. All of these

Answer: Option b

Explanation: Plywood makes use of mechanical and hydraulic presses during its production.

Q 3. Which is of the following wood has a straight grain pattern?

1. White oak
2. Plywood
3. Cedar wood
4. Balsa wood

Answer: Option a

Explanation: White oak is characterized by its straight grain pattern.

Q 4. Which of the following wood has a yellowish-brown appearance?

1. Cedar wood
2. Mahogany
3. Pinewood
4. MDF

Answer: Option c

Explanation: Pinewood has a yellowish-brown appearance.

Q 5. Which of the following wood is a popular choice among many hobby computerized numerical control (CNC) users?

1. SPF Lumber
2. Softwood
3. Mahogany
4. MDF

Answer: Option d

Explanation: MDF is popular among many hobby computerized numerical control (CNC) users and carpenters of small businesses.