Material, Properties and Uses
José Espejo Tudela · Grade 7th · Technology
Wood is a natural material obtained from the trunk and branches of trees. It is composed of cellulose fibres that give it strength and flexibility. It is one of the oldest materials used by humans.
Since Prehistory, humans have used wood to build shelters, make tools, and create fire. Early civilizations used it to build ships, temples, and palaces. In the Middle Ages, it was essential for building cathedrals, mills, and houses.
| Sector | Application |
|---|---|
| 🏠 Construction | Beams, floors, doors, windows |
| 🪑 Furniture | Tables, chairs, shelves |
| 📄 Paper Industry | Paper, cardboard, packaging |
| ⚡ Energy | Biomass and pellets |
| 🎨 Art | Instruments, sculptures |
| Property | Description |
|---|---|
| Density | Hardwoods (oak) 0.7–1.0 g/cm³, softwoods (pine) 0.4–0.6 g/cm³ |
| Moisture | Optimal 12–15%. Excess causes swelling, drying causes cracks |
| Colour & Grain | Each wood has unique colour by fibre distribution |
| Conductivity | Poor conductor of heat and electricity (insulation) |
| Property | Description |
|---|---|
| Composition | Cellulose (40–50%), lignin (20–30%), hemicellulose (15–25%) |
| Combustion | Combustible — burns producing heat, light and ash |
| Decay | Fungi and insects decompose it in humid environments |
| Property | Description |
|---|---|
| Resistance | Withstands tensile and compressive forces along grain |
| Elasticity | Bends and returns to original shape |
| Hardness | Resistance to scratching (oak > pine) |
| Toughness | Absorbs energy before breaking |
| Cleavability | Ease of splitting along grain |
| Stage | Description |
|---|---|
| Felling | Cutting selected trees |
| Delimbing | Removing branches |
| Cross-cutting | Cutting into logs |
| Transport | Moving to sawmill |
| Stage | Description |
|---|---|
| Debarking | Removing bark |
| Sawing | Cutting into planks |
| Drying | Removing moisture |
| Planing | Smoothing surfaces |
Structures (beams, trusses), cladding (parquet, façades), carpentry (doors, windows). Ex: Nordic prefab houses.
Home (tables, chairs, beds), office (desks), decoration (frames, mirrors). Ex: IKEA pine furniture.
40%+ of wood → paper (books, notebooks), cardboard (Amazon boxes), packaging (bags, tetra packs).
Pallets (warehouses), wooden containers (exports).
Firewood and pellets (heating), biomass plants (electricity). Ex: plants in Andalusia.
Musical instruments (guitars), toys, kitchen utensils (cutting boards), sports (skateboards).
| Method | Description |
|---|---|
| Reuse | Restored furniture, decorative pallets |
| Shredding | Shavings for chipboard, compost |
| Recycled Paper | Up to 7 times reusable |
| Biomass | Clean energy in boilers |
FSC: Responsibly managed forests
PEFC: Certified sustainable management
MARIA: José, explain your wood project?
JOSÉ: Sure. Wood is natural material from tree trunks, made of cellulose fibres.
MARIA: Since when is it used?
JOSÉ: Since Prehistory for shelters, tools and fire.
TEACHER: What properties does it have?
JOSÉ: Physical (density, moisture, colour), chemical (composition, combustion) and mechanical (resistance, elasticity, hardness).
MARIA: How is it obtained?
JOSÉ: Trees are felled, delimbed, cross-cut and transported to sawmill. There they're debarked, sawn, dried and planed.
TEACHER: Uses?
JOSÉ: Construction (beams), furniture, paper, energy (biomass), instruments, toys...
MARIA: Does it pollute?
JOSÉ: Positive impacts (absorbs CO₂, renewable) and negative (deforestation, erosion). But fully recyclable.
TEACHER: How is it recycled?
JOSÉ: Direct reuse, shredding for chipboard, recycled paper (7x) and biomass for energy. 1 tonne paper = 17 trees saved.
MARIA: What is circular economy?
JOSÉ: Extract from sustainable forests, use efficiently, design durable and recycle at end. FSC/PEFC certifications guarantee responsible management.
TEACHER: Excellent.
MARIA: Thanks.
END
Wood has been fundamental for humanity since Prehistory. Its unique properties (renewable, resistant, versatile, biodegradable) make it sustainable vs plastic and steel. We must manage forests responsibly: replant, recycle and choose FSC/PEFC products.
"The forest is not just trees — it is a living system that sustains Earth." 🌲