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
Birch tar Birch tar Birch tar or birch pitch is a substance (liquid when heated) derived from the dry distillation of the bark of the birch tree. It is composed of phenols such as guaiacol, cresol, xylenol and creosol. Birch tar was used widely as an adhesive as early as the Middle Paleolithic to early Mesolithic era. Neanderthals produced tar through the dry distillation of birch bark as early as 200,000 years ago. It has also been used as a disinfectant, in leather dressing, and in medicine. 5,000-year-old chewing gum made from birch bark tar, with tooth imprints, has been found in