Welcome to the World of Timbers!
Hello there! In this chapter, we are going to explore Timbers—one of the most versatile and beautiful materials available to designers. From the sturdy oak desk in your classroom to the lightweight balsa wood used in model planes, timber is everywhere. We’ll learn how to tell different woods apart, why they behave the way they do, and how to choose the right one for your projects. Don't worry if it seems like a lot of names to remember; we'll break it down into simple, easy-to-digest chunks!
1. Categorising Timbers: Hardwoods, Softwoods, and Manufactured Boards
Not all wood is the same! Scientists and designers split timber into three main families. The names "Hardwood" and "Softwood" can be a bit confusing because some hardwoods are actually quite soft (like Balsa!).
Natural Timbers: Hardwoods
Hardwoods come from deciduous trees. These are trees that usually have broad leaves and lose them in the autumn. They grow slowly, which often makes the wood more dense and expensive.
Key Hardwoods you need to know:
• Oak: Very strong and durable. Used for high-quality furniture.
• Mahogany: Reddish-brown, easy to work with. Used for expensive furniture and veneers.
• Beech: A hard, "close-grained" wood. It doesn't splinter easily, so it’s great for children’s toys and kitchen tools.
• Balsa: The "odd one out." It is a hardwood but is incredibly light and soft. Great for model making.
• Jelutong: A low-density hardwood, often used for pattern making or carving.
• Birch: Has a very fine grain and is often used to make the layers in plywood.
• Ash: Very flexible and "springy." Often used for tool handles or sports equipment (like baseball bats).
Natural Timbers: Softwoods
Softwoods come from coniferous trees. These trees usually have needles instead of leaves, stay green all year (evergreen), and grow much faster than hardwoods.
Key Softwoods you need to know:
• Pine: Very common and cheap. It often has knots (dark circles where branches grew). Used for construction and cheap furniture.
• Cedar: Contains natural oils that make it rot-resistant. It smells lovely and is used for outdoor fences or sheds.
• Larch: A tough softwood that is also very good at resisting rot. Used for cladding on buildings.
Manufactured Timbers
These aren't "natural" planks. They are made in factories by gluing wood fibres, chips, or layers together. They are usually sold in large, flat sheets.
• Plywood: Made of thin layers (veneers) of wood glued at 90-degree angles. This makes it very strong in all directions.
• Medium Density Fibreboard (MDF): Made from tiny wood dust and glue. It is very smooth and easy to paint but can be heavy.
• Chipboard: Made from larger wood chips glued together. It’s cheap but not very strong and often covered in a plastic laminate (like kitchen worktops).
Quick Review:
• Hardwoods: Broad leaves, slow-growing, examples: Oak, Beech, Balsa.
• Softwoods: Needles/cones, fast-growing, examples: Pine, Cedar.
• Manufactured: Factory-made sheets, examples: Plywood, MDF.
2. Sources and Origins
Timber comes from different types of forests around the world. Where wood comes from affects its price and how it impacts the environment.
• Alpine Forests: High-altitude areas where you find softwoods like Pine, Cedar, and Larch.
• European Forests: Temperate areas where we get many hardwoods like Oak, Beech, and Birch.
• Amazonian Forests: Tropical rainforests, the home of Mahogany. This wood is beautiful but harvesting it can cause serious environmental damage if not done legally.
3. Physical and Working Properties
When you pick a wood, you need to know how it "behaves." These are its properties.
Physical Characteristics
• Knots: These are where branches used to be. They can look nice but can make the wood weaker or harder to cut.
• Grain Structure: The "pattern" of the wood fibres. A "straight grain" is easy to plane, while a "wavy grain" looks beautiful but is harder to work with.
• Density: How heavy the wood is for its size.
• Colour: Natural woods range from very pale (Pine/Birch) to dark reddish-brown (Mahogany).
Working Properties
• Hardness: How well the wood resists scratches and dents.
• Toughness: How well it can absorb a sudden "shock" (like being hit with a hammer) without snapping.
• Durability: How long it lasts, especially when left outside in the rain.
• Elasticity: The ability to bend and then spring back to its original shape (think of Ash).
• Tensile Strength: Strength when being pulled.
• Compressive Strength: Strength when being squashed.
Key Takeaway: Choose your timber based on the job. Need a garden gate? Pick Cedar for its durability. Need a tool handle? Pick Ash for its toughness and elasticity.
4. Environmental and Social Impact
Using wood is great because it is renewable (we can grow more trees), but we have to be careful!
• Deforestation: If we cut trees down faster than they grow, we destroy habitats and speed up global warming.
• Social Footprint: We must ensure logging doesn't destroy the homes of local communities.
• Sustainability: Look for the FSC (Forest Stewardship Council) logo. This means the wood was grown in a way that protects the environment and workers.
• Seasoning: Freshly cut wood (green timber) is full of water. We must dry it out (seasoning) so it doesn't warp or crack later.
• Upcycling: Using old wood (like from pallets) for new products is a great way to be eco-friendly.
5. Stock Forms and Sizes
Wood isn't just sold in random chunks. You buy it in standard "stock forms" to save money.
• Regular Sections: Long planks or square beams.
• Mouldings: Decorative strips (like the skirting board at the bottom of your walls).
• Dowels: Round wooden rods.
• Sheets: Manufactured boards like MDF usually come in large 2440mm x 1220mm sheets.
Pro Tip: When buying timber, you might see the terms PAR (Planed All Round) or PSE (Planed Square Edge). This means the wood has been smoothed down in the factory so you don't get splinters!
6. Shaping and Joining (Specialist Techniques)
How do we turn a plank into a chair? We use tools and joints.
Cutting and Shaping
• Routing: Using a machine to cut grooves or decorative edges.
• Sawing: Using hand saws or power saws to cut wood to length.
• Turning: Using a lathe to spin wood and carve it into round shapes like bowl or table legs.
• Abrading: Using glass paper (sandpaper) to make the surface smooth.
Joining Wood
• Butt Joint: Simple but weak. Just glueing two ends together.
• Dowel Joint: Using wooden pegs to strengthen a joint.
• Mortise and Tenon: A very strong joint where a "tongue" of wood fits into a "hole."
• Dovetail: Very strong and looks beautiful—often used for high-quality drawers.
• Adhesives: PVA is the most common wood glue. It’s white, strong, and goes clear when dry.
7. Surface Treatments and Finishes
Wood is "porous" (it has tiny holes), so it can soak up dirt or rot if not protected.
• Painting: Changes the colour and protects the surface.
• Staining: Soaks into the wood to change its colour but still lets you see the natural grain.
• Varnishing: A clear, hard coating that protects against water and scratches.
• Wax/Oil: Provides a more natural look and feel, though it needs to be reapplied more often.
• Tanilized: Wood for fences is often "pressure treated" with chemicals to stop it from rotting when buried in the ground.
Common Mistake to Avoid: Don't forget to sand your wood with the grain (in the direction of the lines). If you sand across the grain, you will leave ugly scratches that show up when you apply a finish!
Final Quick Review Box
1. Hardwoods: From deciduous trees (Oak, Mahogany, Beech, Balsa).2. Softwoods: From coniferous trees (Pine, Cedar, Larch).
3. Manufactured: Sheets made of bits of wood and glue (MDF, Plywood).
4. Sustainability: Trees are renewable, but we must manage forests carefully (FSC).
5. Finishes: Used to protect the wood and make it look better (Varnish, Paint, Oil).