Creosote is a widely used wood preservative known for its ability to protect wood from decay fungi insects and moisture. It is a dark oily liquid with a distinct smell and it has been used for centuries in railroad ties utility poles marine structures and fencing.
Creosote is derived from coal tar and wood tar with each type having different properties and uses. This topic explores the origins composition applications and safety considerations of creosote in wood preservation.
What Is Creosote?
Creosote is a complex mixture of organic compounds primarily consisting of phenols cresols guaiacols and polycyclic aromatic hydrocarbons (PAHs). It is known for its antifungal and insecticidal properties making it highly effective for wood treatment.
There are two main types of creosote:
- Coal Tar Creosote – Derived from coal tar during the distillation of coal in coke production.
- Wood Tar Creosote – Derived from the pyrolysis of wood particularly from beech oak and pine.
Origins of Creosote: How Is It Derived?
1. Coal Tar Creosote
- Produced from the high-temperature carbonization of coal in industrial coke ovens.
- A byproduct of coal processing in steel manufacturing.
- Contains high concentrations of PAHs making it highly resistant to weathering and biodegradation.
2. Wood Tar Creosote
- Obtained from the destructive distillation of wood mainly hardwoods like beech and oak.
- Contains phenolic compounds that provide antiseptic and antifungal properties.
- Historically used in medical applications and as a mild preservative.
Uses of Creosote in Wood Preservation
1. Treatment of Railroad Ties and Utility Poles
- Railroad companies have used creosote to extend the lifespan of wooden railway sleepers.
- Utility poles are pressure-treated with creosote to prevent insect damage and fungal decay.
2. Marine and Outdoor Structures
- Used for dock pilings bridges and boat components due to its water-resistant properties.
- Helps prevent rot and degradation caused by continuous exposure to moisture.
3. Fencing and Outdoor Wooden Constructions
- Farm fences wooden posts and barns benefit from creosote’s insect-repellent properties.
- Provides long-lasting durability against harsh weather conditions.
4. Historical and Traditional Uses
- Used in the past as a disinfectant antiseptic and medicinal remedy.
- Historically applied to ropes nets and wooden ships to protect them from moisture and insects.
Chemical Composition and Protective Properties
Creosote’s effectiveness as a wood preservative comes from its chemical composition:
- Phenols and Cresols – Act as natural antiseptics and prevent microbial growth.
- Polycyclic Aromatic Hydrocarbons (PAHs) – Make the wood resistant to water and environmental degradation.
- Guaiacol and Xylenol – Provide additional fungicidal properties.
Environmental and Health Considerations
1. Potential Health Risks
- Creosote can be toxic upon prolonged exposure.
- Skin contact may cause irritation rashes or burns.
- Inhalation of creosote fumes can affect the respiratory system.
- Long-term exposure to coal tar creosote is linked to potential carcinogenic effects.
2. Environmental Impact
- Creosote-treated wood should not be burned due to toxic emissions.
- Can contaminate soil and water if not properly managed.
- Many countries regulate or restrict its use to prevent environmental harm.
3. Regulations and Safety Measures
- The U.S. Environmental Protection Agency (EPA) and the European Union have set strict guidelines on its use.
- Creosote is mainly used for industrial and commercial applications with limited residential use.
- Safety precautions such as protective gear and proper ventilation are required when handling creosote-treated wood.
Alternatives to Creosote in Wood Preservation
Due to health and environmental concerns alternative wood preservatives are being developed including:
- Copper-based preservatives (e.g. Copper Azole and Alkaline Copper Quaternary).
- Boron compounds (effective for indoor wood treatment).
- Synthetic fungicides and sealants (offer similar protection without harmful effects).
Creosote derived from coal tar and wood tar has played a crucial role in wood preservation for over a century. While highly effective in preventing rot insect damage and moisture absorption its toxicity and environmental impact have led to increased regulations.
Despite concerns creosote remains an essential industrial wood preservative for applications where long-term durability is needed. However safer alternative preservatives are becoming more popular for modern wood treatment.
