Creosote vs. salt impregnation: which process is the right one?

Choosing the right impregnation process is one of the most important engineering decisions in overhead-line and telecommunications projects. Creosote and salt impregnation both offer proven protective performance - yet they differ significantly in their fields of application, standards requirements and service life in the ground.

Creosote impregnation: the standard for core infrastructure

For over 100 years, creosote impregnation has remained the unrivalled solution for telecommunications and energy networks in many climatically demanding markets worldwide. The technology we use - the Rüping process - prevents poles from bleeding out later during storage and ensures an absolutely uniform impregnation of the wood.

We press hot creosote oil at a controlled temperature of approx. 105 °C to 140 °C under high pressure directly into the wood cells. Impregnation follows a precise application of initial air pressure (100-700 kPa), which saturates the wood optimally. We guarantee a reliable preservative retention of at least 95 to 140 kg per cubic metre of wood.

• Impregnation oil in accordance with EN 13991 (WEI Type B)
• Protection against rot, micro-organisms, termites and cracking
• Colour: dark brown to black
• Recommended markets: UK, Ireland, Middle East, Africa
• Service life in the ground: approx. 15-80 years

Salt impregnation: safety for people and the environment

For projects that require high environmental compatibility - in European low- and medium-voltage networks, in telecommunications networks or in agriculture - we use certified aqueous solutions of copper salts in concentrations of 3% to 6%.

Immediately afterwards, the impregnated wood undergoes a controlled fixation process, permanently anchoring the preservative in the wood in a leach-resistant way. The agents used include Tanalith E3475, Wolmanit CX 8 WB and Korasit KS 2 / KSM - chromium-free systems with proven protection against fungi, insects and termites.

• Chromium-free copper-salt agents (Tanalith, Wolmanit, Korasit)
• Protection against fungi, insects and termites
• Colour: light green, weathering to grey over time
• Recommended markets: EU region, telecommunications near residential areas, energy supply, agriculture
• Service life in the ground: approx. 8 to 25 years (extendable with LoPro® wood-protection bandages)

Decision support for planning departments

The choice depends on three factors: the local approvals and standards of the target market, the soil climate and the required service life below ground, and the client’s environmental requirements. In the EU, salt impregnation is usually the preferred solution; outside Europe, many operators continue to rely on creosote WEI Type B.

Are you planning an overhead-line project and wondering which preservative is best suited to your market? Our engineers will support you in the selection - from robust creosote impregnation and eco-friendly salt impregnation to LoPro® wood-protection bandages that extend service life.