Creosote is added to timber under pressure to provide long-term protection against a wide range of biological and environmental agents of deterioration and degradation, including decay fungi, wood boring insects and termites. Creosote preservative was invented in 1933 and is used in many countries around the world.
The process of creosote involves the drying, grading, treating,vacuuming and inspection of wooden poles. Coal-tar creosote is the most widely used wood treatment today; both industrially, processed into wood using pressure methods such as "full-cell process" or "empty-cell process." In addition to toxicity to fungi, insects, and marine borers, it serves as a natural water repellant. Its commonly used to preserve and waterproof cross arms, pilings, telephone poles, transmission poles, marine pilings, and fence posts. The poles are then treated according to full cell process as follows:
- Treatment Vessel is charged with poles and the treatment vessel is sealed.
- A vacuum is drawn and maintained for an adequate period.
- Without increasing the pressure, the preservative is introduced at the appropriate temperature.
- Allow the cylinder to fill to capacity.
- Apply hydraulic pressure and maintain this pressure (approx 10bar) until the required absorption is attained.
- Release the pressure and pump surplus preservative from the treatment vessel.
- Apply a final vacuum to "dry poles" of excess preservative
After treatment, poles are laid out for final inspection where the poles are inspected for defects and drilled to check the depth of penetration. Acceptable poles are then tagged and stacked according their length and diameter class, ready for dispatch. Creosote is purchased from Arcelor Mittal and FFS Refiners in tanker form. The product adheres to SANS 616 type 2 and 3 specification respectively. R&B Timber Group is a timber business that harvests, processes and pressure treats wooden poles for the domestic and international markets.