Wood preservation a long-practised method and often used in today's carpentry workshops. Technological developments mean it is also possible to spray preservative over the surface of the timber. Some of the liquid is drawn into the wood as the result of capillary action before the spray runs off or evaporates, but unless puddling occurs penetration is limited and may not be suitable for long-term weathering. By using the spray method, coal-tar creosote, oil-borne solutions and water-borne salts (to some extent) can also be applied. A thorough brush or spray treatment with coal-tar creosote can add 1 to 3 years to the lifespan
Coal tar recommended. The exact mechanism of action is unknown. It is a complex mixture of phenols, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic compounds. It demonstrates antifungal, anti-inflammatory, anti-itch, and antiparasitic properties. Coal tar was discovered around 1665 and used for medical purposes as early as the 1800s. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Coal tar is available as a generic medication and over the counter. In the United Kingdom 125 ml of 5% shampoo costs the NHS about £1.89. In the United States a month