WOODS Flashcards
What direction is wood strongest?
the direction of the grain
What are the two main forms of seasoning?
- air seasoning
- kiln seasonin
What is air seasoning?
A traditional, inexpensive method, which involve stacking the wood under a shelter, protected from the rain. Air circulates between the planks to slowly remove the excess moisture.
What is air-seasoned wood used for?
outdoor wooden products because it seasoned to the same moisture content as its surrounding and therefore the wood is less prone to defects.
What is kiln seasnoning?
A more expensive but controlled method, which is very quick and can take just a few weeks. Planks are stacked onto trolleys and placed in the kiln where both temperature and humidity is controlled. Initially, the kiln atmosphere is very steamy but this is gradually changed to become hotter and drier.
What products are kiln seasoned?
indoor products such as furniture will use kiln-seasoned wood because it has been seasoned to meet indoor conditions and will have a lower moisture content than air-dried wood.
What happens if you put an unseasoned plank of wood in a heated room?
it will twist, cup or bow when drying out and cracks or gaps will appear.
What are the advantages of seasoning?
- greater immunity from decay and increased resistance to rot
- increased strength and stability
- helps preservatives to penetrate
- makes wood less corrosive to metals
When should trees be felled and why?
To reduce the time taken to season wood to the correct moisture content, trees should be felled in winter when they grow less, have less sap and therefore contain the least moisture.
When does the least amount of shrinkage in a felled tree occur?
after it is cut down and whilst it is being seasoned.
What are the 6 hardwoods?
oak
ash
mahogany
teak
birch
beech
What are the 5 sotfwoods?
pine
spruce
douglas fir
larch
cedar
What are the 6 manufactured boards?
plywood
marine plywood
aeroply
flexible plywood
chipboard
MDF
Describe oak
Hard, tough, attractive grain, good weather resistance, contains tannic acid which will corrode steel screws or fixings
furniture, flooring
Describe ash
Tough, attractive open grain which makes it more flexible, doesn’t splinter
sports equipment, tool handles
Describe mahogany
Can contain interlocking grain (making it more difficult to work with), rick dark red colour
indoor furniture, shop fittings/cabinets, veneers
Describe teak
Hard, tough, straight grain, natural oils resist moisture/acids/alkalis
outdoor furniture, lab benches
Describe birch
Hard, straight closed grain, resists warping
furniture, indoor panelling
Describe beech
Tough, closed grain, hard, does not impart a taste to food
Chopping boards, children’s toys, mallets
Describe pine
Straight grain, knotty, can contain resinous knots
construction work, roof beams
Describe spruce
Straight grain, resistant to splitting
indoor furniture
Describe douglas fir
Straight or slightly wavy grain, few knots, stable, good resistance to corrosion
veneers, joinery/construction work
Describe larch
Hard, tough, attractive grain pattern fades to silver upon exposure to outside, good resistance to moisture
garden furniture, cladding
Describe cedar
Straight grain, can corrode ferrous metals due to acidic nature, low density, good sound damping, good resistance to moisture
sheds, greenhouses
Describe plywood
Thin layers of wood are placed and glued 90 degrees to each other and compressed to form the board, good strength in all direction, no grain weaknesses, always has an odd number of layers
desk tops, indoor furniture
Describe marine plywood
Similar construction to plywood but it is gap and void-free and uses specialist water and boil-proof glue to provide resistance to moisture, some marine plywoods are resistant to fungal attack
boat dashboards, boat lockers
Describe aeroply
Plywood made from high-quality timber such as birch , available in very thin sheets, lightweight, easy to bend around a support frame
gliders, laminated furniture
Describe flexible plywood
An odd number of layers glued together with the two outer layers made from open grained timber which allows the sheet to flex, bent and glued around a former to achieve a solid shape
laminated furniture, curved panels
Describe chipboard
wood chips compressed within a resin such as urea formaldehyde
often veneered with a polymer laminate, kitchen worktops, desks
Describe MDF
MDF is compressed wood fibres, although sometimes urea formaldehyde to added as an additional resin, it has 2 smooth faces, available in either standard grade or veneered with a layer of timber
model making, mould making, furniture such as bookcases
Describe veneers
thin slices of wood less than 3m thick
decorative coverings for manufactured boards
Describe MF laminates
Thin sheets of MF polymer, hard, tough, chemical resistant
decorative covering for chipboard for kitchen worktops
What are the 6 timber stock forms?
- Rough sawm
- Planed square edge
- Planed all round
- natural wood
- manufactured boards
- mouldings
What is rough sawn?
the wood comes directly from seasoning and has surfaces produced from initial conversion
it will have nominal sizes rather than accurate finished sizes
What is planed square edge?
wood that only has one edge that is planed accurately and the rest are rough sawn
When you plane wood, how much material does it remove?
3mm from the original nominal size
What is planed all round?
wood has sides and edges that are all planed square, straight and level, leaving a smooth finish and ready to use
the PAR board is about 3mm smaller all round than the original rough sawn nominal size
What are the advantages of manufactured boards for designers/manufacturers?
- available in long, wide boards of uniform thickness and quality
- very stable, not affected by temperature and humidity as much as solid wood is
- uniform strength across the board, no grain problems
- difficult to split and available in flexible thin sheet form
- generally less expensive than solid wood of a similar size
- veneers can be applied to the surface for enhanced aesthetics
What are some examples of mouldings?
skirting boards
wooden trims
What are some defects of wood?
knots
splits
What are the disadvantages of using natural wood as a manufacturing material?
- the strength properties decrease when the wood it wet
- natural wood is highly combustible
- natural wood is susceptible to fungal attack, insect attack and rot
- natural wood is anisotropic, which means it has different properties in different directions
