2. Physical damages such as those caused by heat, humidity, stretching, shrinkage, breakage, fractures, splits and the actions of climatic conditions.

3. Mechanical damages such as friction, trampling or breakage due to weight.

4. Chemical damages such as contact with acid, alkaline, adding oxygen and burning.

The damages from the first cause can be prevented by using wood preservation solutions which are toxic for the three causes of wood rotting, thus enabling us to prolong the term for using the wood. Wood capable of resisting damages without depending upon wood preservation solutions is called naturally resilient wood. Wood preservation solutions are chemicals that are toxic to the causes of wood damage which are mold, insects and tunicates. These wood preservation solutions generally have to be liquids in order to conveniently penetrate the wood, which can be both in the form of chemicals mixed with solutions, mixed oils or water soluble chemicals, which are categorized into the following three types:

Preserving Wood

1.Creosote, or a mixture acquired from coal tar, which is highly effective, does not dissolve in water, adheres to wood for a long period of time, helps prevent the wood from breaking, does not corrode metals, can be used in jobs requiring high levels of durability such as wood column and wooden electrical poles. Creosote is usually

used in the full cell process, but has disadvantages in that it has a strong odor, cannot be painted over and is black in color.

2.Chemicals mixed with oil solutions such as Tanalith T (an oil soluble chemical containing Permethrin properties and can be used by dipping, spraying or painting).

3.Chemicals mixed with water used in homes such as boron compounds, CCA: Copper Chrome Arsenic. Boron compounds are commonly used in preserving para-rubber wood or soft wood used to make furniture used inside houses by compression so the amount of leftover chemicals will be 0.2% BA. CCA is used with wood requiring special resilience to sun and rain because it adheres to wood well. The full-cell process is normally used.

Wood Preservative Qualities

1. Safe or minimally hazardous for users.

2. Effective and must be toxic for things that destroy wood.

3. Durable and able to stay in wood for a long period of time.

4. Low cost and cost-effective with the need for wood preservation.

Wood Coating Methods

1.Compression methods involve compression by use of a compression drum and are divided as follows:

-Full-cell process i.e. creating a vacuum (-0.84 bar) in combination with pressure (150-200 psi)

-Free-cell process i.e. pressurization alone (use air pressure of 60 psi and compress fluid at 150-200 psi)

-Alternating pressure process i.e. alternating use of pressure and vacuum several times.

-Interposed vacuum processes similar to full cell processes, but using lower pressure.

2. Pressure is not used in painting, praying, dipping or soaking methods