Wood and Modified Wood Humans have used wood

Wood and Modified Wood

• • Humans have used wood for construction for centuries because of its abundance and ease of use. The trunk is most used in this industry.

Two classes of wood: – Hardwood - Softwood Hardwood is characterized as having more resistance and longevity than softwood.

Types of Woods Family of Tree Hardwood Leafy trees (maple, oak) Softwood Resinous (pine, cedar, spruce) Uses -Furniture -Flooring -Plank - Plywood (construction materials)

Transforming Timber to Lumber 1. Cut down a tree.

2. The branches are removed. 3. The trunk is cut into sections.

4. The cut sections are transported to a wood mill.

5. The bark is removed.

6. The trunk is cut into a beam.

7. The beam is cut into wood planks for construction. Ex. 2 x 4 1 x 3 4 x 4

8. The wood planks are dried.

• Wood has certain characteristics that dictate its application. Ex. Durability (soft wood or hard wood) Elasticity Mass Colour (white, pink, yellow, brown) Tint (light or dark) Resistance (decomposition) Ease of use and assembly

• Unlike other materials (plastic, metal) the life span of wood can be shortened due to insects, mushrooms and mold.

Properties of Different Types of Wood

Species Hardness Spruce soft Resistance to Usage Durability Mass Colour Uses medium weak light - Whitishyellow - reddish - framework - paper Pine soft weak Passable resistance light Cream Lightbrown - furniture - doors Maple hard very strong weak heavy Light brown - floors - furniture Oak hard very strong high heavy Light brown - boats - furniture - floors Ash hard strong medium heavy white - hockey sticks - snowshoes

Modified Wood • Natural wood can be transformed to modified wood to lower costs. • Modified woods are woods where substances are added substances to obtain properties different from natural wood. Ex. Particle Board is made by reducing medium quality wood into particles then gluing it back together.

Characteristics of Modified Wood Types of Modified Wood Composition Advantages Disadvantageous 3 mm layers stacked in odd numbers - Resists cracks due to contracting and expanding - Economical Glue can be toxic Wood broken Particle Board down into chips then mixed with glue and set to a board due to heat and pressure -Reuse wood -Economical - Uniform properties Glue can be toxic Plywood Examples

Types of Modified Wood Fiber Panels Composition Wood reduced to fibers then mixed with glue and set to a board by heat and pressure. Denser than particle board. Advantages Disadvantageous Economical Easy to use Uniform properties Inconvenient (Heavy) Needs to be painted Glue can be toxic Examples