Defects in Wood

Seasoning of Wood

Preparation of Wood

Logging

1. Cutting of the tree.

2. Skidding – when logs are moved to an assembly area loaded to transport equipment then carried out of the forest to the sawmill.

3. Bucking – the process of sawing into smaller pieces.

The harvesting of the tree

crops consisting of a

sequence of operations

such as:

Previously, all felling and bucking operations

were done by the use of axe, saw, and

wedges. Lately, however, the felling of

trees were done using motor powered

chain saw.

Terminologies

Skidded – when the log is dragged and

carried down to an assembly area.

Yarded – when logs are delivered through

the cable or a helium filled balloon.

Lumbering – the operation performed in

preparing wood for commercial purposes.

Sawing – cutting logs.

Two Methods of Log Sawing

Employed are:

1.The Plain or

Bastard sawing

- is by cutting the logs

entirely through the

diameter with a parallel

chord tangential to the

annual rings.

2. The Quarter of Rift sawing

a.Radial method

b.Tangential

method

c.Quarter

tangential

d.Combined Radial

and Tangential

Main

Defects in Wood

- Irregularities found in wood are considered

as defects. The most common defects are:

A. Abnormal Growth

B. Due to Deterioration

A. Abnormal Growth are identified as:

1.Heart Shakes –

radial cracks

originating at the

heart of the logs.

2. Wind Shakes or

Cup shakes –

cracks or breaks

across the annual

rings of timber.

3. Star Shakes –

composed of several

heart shakes in a star-

like manner.

4. Knots – usually occurs

at the starting point of

a limb or branch of the

wood.

B. Due to deterioration caused by:

1.Dry-Rot – the

presence of

moisture in

seasoned

wood caused

by fungi.

2. Wet Rot – usually takes place

sometime in the growth of trees caused

by water saturation.

Main

Seasoning of Wood

Seasoning – drying of lumber.

The water contained in a freshly cut

wood constitute about one third to more

than two thirds of its weight. The removalof much of this

moisture is

accomplished by way

of seasoning also

known a conditioning

or curing.

Two Methods of Seasoning Wood

1. The Natural or Air Seasoning

a. Lumber is piled

vertically outdoor

inclined at about

10 degrees.

b. Lumber is piled

in a well-

ventilated shed.

2. The Artificial Seasoning

- is the process adopted

for quick drying of wood.

Under this method,

lumber are stacked inside

a drying kiln and then

subjected to steam and

hot air under pressure.

Wood that undergone this

process are considered inferior

in quality compared to those

that were dried by natural or air

seasoning process.

The Artificial Seasoning Methods

Employed are:

1.Forced Air Drying – fans are used

to booster the circulation of air a

preparatory process to kiln drying.

2. Kiln Drying – the lumber is dried in a

specially built chamber wherein

temperature and humidity as well as

the circulation of air is under control.

3. Radio Frequency Dielectric Drying – a

very fast method of drying lumber

using a radio frequency dielectric heat.

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