Material classification - Wood

Question 1

Growth of a tree definition

Answer 1

trees grow during summer periods and slow during winter months causing the rings, wood is not consistently hard, there are different layers all the way through

Question 2

Faults in wood

Answer 2

wood issues - grain, knots, cupping, twisting
Biological issues - insects, fungi

Question 2

Kiln seasoning - how is it done

Answer 2

planks are stacked on trolleys and placed in a kiln where temperature and humidity is controlled, steam is used in a kiln to heat timber and a vacuum is then created, very precise moisture levels are achieved and many insects and fungi are killed, airflow is important to dry the wood out

Question 2

Wood structure definition

Answer 2

wood has natural grain, slow growing wood (tight together cells) is stronger, wood is strong in the direction of the grain

Question 2

Natural air seasoning - how is it done

Answer 2

slabs stacked and air is allowed to flow around them, on average it takes one year to season 25mm of thickness, normally sheet metal over the top to stop the rain

Question 2

Seasoning of wood definition

Answer 2

removing moisture of the wood to around 10% to reduce defects

Question 3

What happens if you don’t season wood

Answer 3

it will twist, warp, cup, bow or crack, if seasoned: les decay will occur, increased strength, helps preservatives penetrate, less corrosive, but it can shrink due to seasonal changes

Question 4

Air vs kiln seasoning

Answer 4

air = cheap, exterior use
kiln = expensive but fast - interior use

Question 5

Conversion of wood definition

Answer 5

process of sawing logs into commercially viable timber - slab or radial/quarter sawn

Question 6

Slab sawn wood definition

Answer 6

cut straight across log proving planks of equal or variable thickness, simple, cheap, fast, timber tends to be less stable leading to cupping

Question 7

Radial/quarter sawn wood definition

Answer 7

time consuming, expensive, timber produced is stable, thinner widths, cutting results in good grain pattern

Question 8

Wood toxicity definition

Answer 8

wood dust can be toxic when breathed in, use good extraction and PPE, wood is carcinogenic

Question 9

Stock forms of wood

Answer 9

planks

Question 10

How can planks be prepared and definitions

Answer 10

rough sawn - wood comes directly from seasoning and has rough surfaces

Planed both sides (PBS) - only top and bottom faces are planed to achieve a smoother finish the rest are rough sawn

Planed all round (PAR) - both wood faces an edges are planed except the front and back edges leaving a smooth finish

Question 11

Hardwood classifications

Answer 11

grown across the world, broad-leafed, deciduous, more durable than soft woods, variety of colour and texture, slow growing, more expensive

Question 12

Hardwoods AD/DIS

Answer 12

AD - looks nice, weigh a lot, can be stained, no finish required

DIS - small stock form limited by tree size, heavy - good/bad, needs predrilling, slow growing

Question 13

Softwoods classifications

Answer 13

mainly from northern hemisphere, conifers, fast growing, straight trunks

Question 14

Softwoods AD/DIS

Answer 14

AD - looks nice, weighs less than hardwood, can be stained, no finish required, no predrilling, cost less, fast growing

DIS - small stock form, can split/twist, dent easily, contains more knots that hardwood