6) Performance characteristics of woods Flashcards
Describe rough sawn
Wood that comes direct from seasoning and has rough surfaces produced during initial conversion
Has nominal sizes rather than accurate finished sizes and is the cheapest stock form
Describe planed square edge (PSE)
Wood only has one edge that is planed accurately; the rest are rough sawn
Planing removes about 3mm from the original nominal size
Describe planed all round (PAR)
Wood has sides and edges that are all planed square, straight and level, leaving a smooth finish
About 3mm smaller all round than original rough-sawn and most expensive
State the three types of woods
1) Natural wood
2) Manufactured boards
3) Mouldings
Describe natural wood
Only available at the maximum width of the tree
To produce wider, planks need to be joined together
Planks should be joined with the end grain going in different directions to avoid distortion
Describe manufactured boards and give standard sizes
Man-made and produced in large sheets typically 1220x2440
Wide surfaces can be joined without the need for joining processes
Describe mouldings
Premade such as skirting boards or wooden trims available in standard lengths
Give four facts about air seasoning
1) Wood is stacked in a shelter outside, protected from the rain
2) Air circulates between planks to remove excess moisture
3) Slow, up to one year and inexpensive
4) Used for outdoor products
Give four facts about kiln seasoning
1) Wood is stacked on trolleys
2) Kiln dried
3) Quick, only a few weeks & cheap
4) Used for indoor products
Why is wood seasoned?
1) gives greater immunity from decay and increased resistance to rot
2) Increases strength and stability
3) Helps preservatives to penetrate
4) Makes wood less corrosive to metals
