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 in the workplace by breathing, skin contact, or eye contact. The Occupational Safety and Health Administration (OSHA) has set the permissible exposure limit) to 0.2 mg/m benzene-soluble fraction over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 0.1 mg/m cyclohexane-extractable fraction over an 8-hour workday. At levels of 80 mg/m, coal tar pitch volatiles are immediately dangerous to life and health. When used as a medication in the U.S., coal tar preparations are considered over-the-counter drug pharmaceuticals and are subject to regulation by the FDA. Coal tar Coal