Drying Timber

Question 1

Timber derived from freshly felled wood is said to be _______, meaning that cell cavities _________

Answer 1

green; contain free water

Question 2

water in the wall fibers makes the wood…

Answer 2

structurally weak and susceptible to attack by insects and fungi

Question 3

amount of moisture that the wood contains

Answer 3

moisture content

Question 4

process of reducing moisture content

Answer 4

drying or seasoning

Question 5

main objectives of timber drying

Answer 5

• reduce its weight
• increase its strength property
• increase resistance from insect and fungal attacks
• provides stability with regards to moisture movement
• increase workability for machines and hand tools
• enable wood preservation treatments to be applied
• enable fire retardant treatments to be applied
• enable surface finishes to be applied
• enable adhesives to be applied
• reduce the corrosive properties of some wood
• reduce heat conductivity thereby increasing insulation properties

Question 6

methods used to moisture content

Answer 6

• air drying
• kiln-drying
• air drying followed by kiln drying

Question 7

relies on sun and wind; most unreliable process

Answer 7

air drying

Question 8

air drying process

Answer 8

1. timber is stacked in controlled condition under the sun

2. the sun evaporates the moisture and air carries away the moisture

Question 9

succes of air drying process depends on:

Answer 9

1. weather protection
2. site condition
3. stacking
4. climactic condition for drying

Question 10

reduction in moisture can take many months depending on:

Answer 10

1. drying environment and amount of exposure
2. type of wood
3. type of species
4. thickness of timber

Question 11

important elements of air drying

Answer 11

1. risen of the ground
2. clear of ground vegetation
3. free air circulation
4. protection from the weather

Question 12

clpseable chamber where green timbers are maneuvered by trolleys to undergo a controlled drying method

Answer 12

Kiln drying

Question 13

timber is moved in stages through a tunnel dryer

Answer 13

progressive kiln

Question 14

kiln methods require controlled:

Answer 14

• heat
• humidification
• ventilation
• air circulation

Question 15

three stages of kiln drying

Answer 15

1. heating the wood without drying; low heat, high humidity
2. starting and continuing drying; increased heat, less humidity
3. final stages of drying; high heat, slight humidity

Question 16

sealable drying chambers which house batches of timbers until loaded in trolleys until their drying schedule is complete

Answer 16

compartment kilns

Question 17

green timbers enter the dryer in one side and emerges from the other side after a period of time which can be as short as 3 days depending on the species and cross section cut

Answer 17

progressive kiln or continuous dryer