Timbers

Question 1

Properties of softwood

Answer 1

• they mainly grow in cooler climates
• they are cone baring - therefore coniferous
• they have a looser grain structures
• they are often used as a building material
• usually softer and easier to work with
• they grow tall and straight - makes it easier for the manufacturer to cut long straight planks of wood
• they are evergreen meaning that they don’t loose their leafs in the winter
• they grow faster so therefore are cheaper

Question 2

Properties of hardwood

Answer 2

• most hardwood trees are deciduous which loose their leaves in the winter
• tend to have a tighter grain structure
• they can be very expensive as they take a long time to grow
• they are usually quite hard
• there are evergreen hardwood trees that are found in tropical or sub-tropical countries such as South America
• they are broad leaf trees it’s seeds are enclosed in the fruit that the tree produces
• they generally grow in temperate climates
• around 100 years to grow fully

Question 3

Properties of manufacturing board

Answer 3

• boards are available in many thicknesses
• boards are inexpensive so are often used instead of real woods
• they have been developed mainly for industrial production as they can be made in very large sheets of consistent quality

Question 4

What are manufacturing boards and how are they made?

Answer 4

Manufacturing boards are timber sheets which are produced by gluing wood layers or wood fibres together

Question 5

What are manufactured boards mainly made out of ?

Answer 5

Manufactured boards are mainly made out of waste wood

Question 6

What’s a veneer ?

Answer 6

A veneer is a thin layer of real wood that is usually placed over manufacturing boards to improve their appearance or properties

Question 7

Name some softwoods

Answer 7

Larch
Pine
Redwood
Spruce
Cedar
Douglas fir

Question 8

Name some hardwoods

Answer 8

Oak
Ash
Beech
Balsa
Birch
Mahogany
Teak

Question 9

Name some manufactured boards

Answer 9

Plywood
Marine plywood
Aeroply
Flexible plywood
Chipboard
Medium density fibreboard (MDF)
Veneers and melamine formaldehyde laminates

Question 10

Name the performance characteristics of woods

Answer 10

• Grain pattern
• Grain direction
• Surface defects
• Warpage
• Shrinkage
• Splitting
• Joining
• Forming
• Steam bending
• Laminating
• Machining qualities
• Resistance to decay
• Moisture resistance
• Toxicity

Question 11

Name the stock forms of timber

Answer 11

• rough sawn ( not smooth )
• lots of different sizes, planks and strips
• PSE ( planed square edge ) smooth all round
• PAR ( planed all round ) all the sides and edges are planed square, straight and level, leaving a smooth finish and ready to use
• natural timber
• manufactured boards
• mouldings - skirting boards, frames
• veneers - thin cuts of wood glued onto other materials

Question 12

What happens if wood rots in landfill or is burned?

Answer 12

It releases greenhouse gases which contribute to climate change

Question 13

What do trees do to carbon ?

Answer 13

Trees act as ‘carbon sinks’ that absorb the gases

Approximately 25% of the fresh weight of timber is carbon

Question 14

What does using recycled timber products do ?

Answer 14

Using recycled timber products reduces deforestation and retains the locked-in carbon

Question 15

What is seasoning

Answer 15

Seasoning is the process of removing excess moisture from freshly cut trees

Question 16

What are the 2 types of seasoning ?

Answer 16

• Natural seasoning ( air seasoning )
• kiln seasoning

Question 17

What are the advantages / disadvantages of natural seasoning ?

Answer 17

Advantages:
- cheap
- Some say the timber is stronger than kiln seasoned

Disadvantages:
- Very slow ( year per inch thickness )
- Bugs and fungus survive
- Water content hard to control accurately
- Ends of planks can split

Question 18

Advantages and Disadvantages of kiln seasoning

Answer 18

Advantages:
- Accurate water content achieved
- 12% or lower moisture content achievable
- Kills bugs and fungus
- Fast

Disadvantages:
- Expensive

Question 19

What is Splitting ( Timber defect ) ?
Where does it occur? What can you do stop/help it ?

Answer 19

• Usually occurs at the end of a plank
• Ends are cut off to remove splits
• Generally an unavoidable problem
• Painting the ends of planks can help slow down the drying of the ends

Question 20

What are knots (timber defect) ?

Answer 20

Knots are where a branch was attached to a tree

Live knots are okay and can be decorative

Dead knots need to be avoided

Question 21

What is Dry Rot ( timber defect )
What is it caused by ?

Answer 21

• Serious problem caused by incorrect seasoning or poor building maintenance
• Dry rot is caused by timber being over 20% moisture content and not ventilated

Question 22

What is Woodworm ? And what is a sign of woodworm ?

Answer 22

The common furniture beetle lays eggs on timber

The larvae eat the wood for a year and then emerge as adult beetles

‘Frass’ or wood dust is a sure sign of woodworm

Question 23

Name some physical characteristics of oak and what is oak usually used in ?

Answer 23

Strong, hard, heavy and dense with a tight grain structure
Very resistant to fungal infestations and insect infestations

Oak is commonly used for furniture, joinery, flooring, panelling, decking and veneers.

Oak is the sturdiest material you can use when woodworking - it is good/bad because its very heavy

Question 24

What are the physical properties of Beech and what is beech used in ?

Answer 24

Beech is a hard wood, moderately heavy and solid, with good mechanical properties. It has particularly high resistance to compression, though less so to bending or tension because of its short fibres. Very fine texture. It has a tendency to warp substantially when exposed to changes in humidity.

Beech timber is suitable for a variety of purposes, including fuel, furniture, cooking utensils, tool handles and sports equipment

Question 25

What are the physical properties of Ash and what are the uses for Ash ?

Answer 25

Ash wood is strong, dense, lighter in colour than oak and smooth to the touch. It takes gluing, stains and polishes well, making it popular for woodworking projects. Less prized than oak and more physically appealing than beechwood, Ash is a great middle-ground for many tasks.

Ash wood is susceptible to insects and fungus when exposed to soil. This makes the material unsuitable for outdoor furniture pieces.