Woods Flashcards
Stock form 1
Which are the most expensive and least and why?
Rough sawn
PSE
PAR
Planing definition
Rough sawn cheapest cuz has rough surfaces, comes from seasoning, comes in nominal sizes
Plane squared edge - only 1 edge planed accurately, rest rough sawn.
Planing removed 3mm from original nominal sizes
Planed all round, all square, straight, level, smooth finish ready to user. Most expensive.
Stock form 2
Natural wood - what’s a limitation of it. How can you make large areas with it.
Manufactured wood - typical size? What’s an adv over natural wood
Mouldings - what are they
Natural, from trees, available at max width of tree.
Planks need to be joined together, to make wide area.
Manufactured typically 1220x2440
No need to join, can make wide area from 1 sheet
Premade Mouldings eg skirting boards readily available up to 4m
Characteristics
Name 1 obvious ADV of wood.
Grain strength - what is it strong/weak along
Adv of seasoning What the process involve reducing What does it prevent - 5 What does it increase resistance to What does it increase How does it make it easier to use with metals How does it help preservatives
Biodegradable.
Strong along grain, weak across. Some bs about tracheids and lignin, read book.
Seasoning reduces excess moisture Prevents defects eg twisting, warping, cracks, bowing or cupping. >Resistance to rot, decay >Strength, stability >Makes wood less corrosive to metals Helps preservatives to penetrate
Characteristics
Air and kiln seasoning
Air:
Adv?
How is it done, how long does it take
What is the wood used for
Kiln:
Dis?
How’s is it done, and how long does it take
What’s it used for
Air - traditional, inexpensive
Stacked on shelter, air circulates to < moisture, takes up to year,
wood used for outdoor products
Kiln - expensive temp controlled.
Stacked on trolleys, initially steamy then hot and dry.
Quick, few weeks
Used for indoor products
Characteristics
Toxicity - what part of wood can be harmful. How can it cause harm - 2 things
Name 2 preventions to the risks
Depends on species. Wood dust and sap can be harmful. Also can cause respiratory irritation + hardwoods listed as carcinogenic.
Hardwood+softwood dust have workplace exposure limits at 5mg/m3 under COSHH
Use ppe and extraction
M Hardwood - Oak
Furniture, floor, joinery, boat, cladding
Hard, tough, good weather resistance
Attractive grain
WILL CORRODE steel screws due to tannic acid
M beech
Chairs, tools(mallet), chopping boards, turned bowls Hard, Tough Close grained Available in: Steamed - white Unsteamed - pink
O Ash Mahogany S TEAK Birch
Ash - tool handles, ladders, laminating, sports stuff. Attractive open grain, MORE FLEXIBLE
Mahogany - indoor furniture, veneer, shop fittings/cabinates .
Interlocking grain, HARDER to WORK on.
RICH, dark red colour
TEAK - outdoor furniture, lab benches, traditional boat decks
The natural oil RESISTS moisture, acid, alkali,
Hard, tough, straight grain
Birch - furniture, indoor paneling, veneers used for birch faced plywood construction.
RESIST WARPING, hard, straight close grain
M Pine
S spruce
Pine
Veneers, interior joinery, construction work, roof beams
Straight grain, KNOTTY, can contain resinous knots
Spruce
Indoor furniture
Straight grain, RESISTANT to SPLITTING
O softwood
S Douglas fir
Larch
Cedar
Douglas fir - veneer, joinery and construction, plywood construction.
Corrosion RESISTANCE, STABLE, straight or slightly wavy grain
Larch - garden furniture, cladding, DECKING, fencing
Attractive grain, tough hard, fades to silver upon exposure to outside
Cedar - SHEDS, green house, beehives, exterior cladding, interior paneling
ACIDIC can corrode ferrous metals, good rot and insect RESISTANCE, sounds damping, low density, straight grain
Manufactured
M MDF
M ply
MDF - Model, mould making. Furniture items
Compressed wood fibres, UF added as resin, smooth.
PLY - Structural work, desktops, indoor furniture, floorboards
thin layers glued 90 degrees to eachother.
Good strength in all directions. Always odd no. layers
Manufactured O Marine ply Aeroply Flexi ply Chipboard
Marine - boat panelling
Gap, void free, uses WBP glue so moisture resistant. Simar properties to ply. Can be resistant to fungal
Aero- gliders, laminated furniture
Ply made from high quality timber like birch. Lightweight easy to Bend around frame
Flexi - laminated furniture, curved panels
Odd no. Layers with 2 outer layers made from open grained timber ( ash )
Chipboard - often veneered, kitchen worktops, shelving, flatpack furniture
Wood chips compressed with resin eg UF
Veneers and laminates
Veneer is slice of wood less than 3mm thick
Covering for manufactured boards
MF laminates, are thin sheets of MF polymer, hard, touch, chemical resistant.
Used as decorative covering for kitchen worktops etc
