Application methods

Selection of techniques to apply preservation is important . Otherwise , preservation may not penetrate into timber sections . The followings are various techniques :

• Brushing or spraying . 

1. Limited penetration 
2. For in situ remedial work 
3. Require several coats . 

• Dipping 

1. Immersion in preservative for a period . 
2. Open tank method - preservative heated then cooled while timber is submerged to get better results . 
3. Not suitable for hardwoods or low-permeability softwoods . 

• Double vacuum process 

1. Vacuum is applied to timber in sealed chamber . 
2. Preservative is introduced . 
3. The vacuum released , forcing preservative into wood . 
4. After a soaking period  ,vacuum is reapplied to eject excess preservative . 
5. Widely used for organic preservatives for external joinery such as window frames . 

• Pressure impregnation 

1. Used for water based and tar oil preservatives 
2. Air surrounding timber is compressed , preservatives introduced under high pressure forcing it into timber . 
3. Expensive . 
4. Longer to dry 
5. Good protection .