For years, creosote has been used to preserve wood. Today creosote is still used to preserve rail ties and telephone poles. Fence posts were commonly preserved with creosote until potentially harmful chemicals were found in it. Creosote is the byproduct of condensed wood or oil smoke. When condensed, the smoke turns to an oily, sticky substance that is yellow in colour. Creosote is also flammable before applied to wood and allowed to set up and harden.
Coal tar is the most common type of creosote. Industrial grades of coal tar produce this type of creosote when burnt. Coal tar creosote is a thick and oily substance that is black in colour. Coal tar creosote was used as an ingredient in treatments of skin diseases in the past. However, the treatment was ended when potenitally harmful chemicals were identified, according to the United States Public Health Service. Coal tar creosote contains many chemicals and not all of them have been identified. Of those that have been identified, three have been noted as having the potential to cause health problems.
Creosote oil is used to preserve sleepers and transmission poles from the destruction caused by bugs or elements. Creosote oil has a very strong smell and should be applied only to outside applications. A diluted form of creosote oil can be applied to garden or yard fencing and other wooden areas of the outside of a house where rot and moisture may cause damage to the wood. Creosote oil is also very effective at protecting poles from woodworm.
Beech wood creosote is obtained through the high-temperature treatment of beech wood as well as other types of woods. In the past, beech wood creosote was used as a medicinal treatment for a cough. The strong smell of the beech wood creosote was thought to help open the lungs of the patient. However, it is now known that beech wood creosote contains chemicals that are considered harmful, such as phenol and cresols.
As wood and leaves are burnt in the fireplace of a house, creosote can build up in the chimney. This creosote appears as a thick, black substance that lines the walls of the chimney. If an excessive amount of creosote builds up, it can become a fire hazard. Larger amounts of creosote will develop in a chimney if the fire produces thick, heavy smoke. The cleaner the fire burns with less smoke, the smaller the amount of creosote that will be deposited on the walls of the chimney.