timber 3

Question 1

what does durability mean?

Answer 1

resist processes of degradation

Question 2

name 5 types of degradation

Answer 2

1. chemical
2. organic
3. photochemical
4. thermal
5. mechanical

Question 3

in photochemical degradation.. what is broken down in 1. Uv light…2. visible light ?

Answer 3

uv- lignin

visible- cellulose

Question 4

browning of wood to produce caramel like smell refers to what type of degration?

Answer 4

THERMALL

Question 5

What is mechanical degradation?

Answer 5

when under load for a long time, loss of strength and stiffness
where timber has been overstressed in compression- localised compression damage i.e. kink bands

Question 6

what is white rot?

Answer 6

1. fungi which cause lignin, hemicellulose and cellulose to decompose
2. timber becomes lighter
3. fibrous mass forms

Question 7

what is brown rot?

Answer 7

1. fungi which chemically decomposes cellulose and hemicellulose
2. work darkens
3. wood breaks into cubes

Question 8

brown and white rot cause loss of what to the timber?

Answer 8

1. strength
2. stiffness
3. toughness
4. mass

Question 9

requirements for substances for protection of timber?

Answer 9

1. toxic to humans etc
2. economic
3. preservability
4. non corrosive
5. toxic to insects/ fungus

Question 10

how can preservatives be applied?

Answer 10

1. spray and brush
2. open tank application
3. pressure application
4. deluging, dipping, steeping