Creosote
A dark, oily wood preservative derived from coal tar used to protect railroad ties, utility poles, and marine pilings, restricted to industrial use and not approved for residential applications.
In-Depth Explanation
Creosote has been one of the most effective wood preservatives for over 150 years, providing exceptional protection against decay fungi, insects, and marine borers in demanding conditions. The dark pungent liquid penetrates deep into wood cells during pressure treatment, extending service life of poles and ties to 30 years or more. However, creosote contains polycyclic aromatic hydrocarbons classified as probable carcinogens, which is why the EPA restricts its use to certified commercial applicators. Creosote-treated wood should never be used for garden beds, playground equipment, or any application where people or food crops contact the surface. Reclaimed railroad ties are sometimes used in landscaping but this practice is discouraged due to health risks.
Usage Example
The utility company installed creosote-treated southern yellow pine poles rated for a 30-year service life in direct ground contact.