Creosote
Creosote
Main page
2303587

Creosote

logo
Community Hub0 subscribers
What are your thoughts?
Be the first to start a discussion here.
Be the first to start a discussion here.
Creosote

Creosote is a category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood, or fossil fuel. They are typically used as preservatives or antiseptics.

Some creosote types were used historically as a treatment for components of seagoing and outdoor wood structures to prevent rot (e.g., bridgework and railroad ties, see image). Samples may be found commonly inside chimney flues, where the coal or wood burns under variable conditions, producing soot and tarry smoke. Creosotes are the principal chemicals responsible for the stability, scent, and flavor characteristic of smoked meat; the name is derived from Greek κρέας (kreas) 'meat' and σωτήρ (sōtēr) 'preserver'.

The two main kinds recognized in industry are coal-tar creosote and wood-tar creosote. The coal-tar variety, having stronger and more toxic properties, has chiefly been used as a preservative for wood; coal-tar creosote was also formerly used as an escharotic, to burn malignant skin tissue, and in dentistry, to prevent necrosis, before its carcinogenic properties became known. The wood-tar variety has been used for meat preservation, ship treatment, and such medical purposes as an anaesthetic, antiseptic, astringent, expectorant, and laxative, though these have mostly been replaced by modern formulations.[citation needed]

Varieties of creosote have also been made from both oil shale and petroleum, and are known as oil-tar creosote when derived from oil tar, and as water-gas-tar creosote when derived from the tar of water gas.[citation needed] Creosote also has been made from pre-coal formations such as lignite, yielding lignite-tar creosote, and peat, yielding peat-tar creosote.[citation needed]

The term creosote has a broad range of definitions depending on the origin of the coal tar oil and end-use of the material.

With respect to wood preservatives, the United States Environmental Protection Agency (EPA) considers the term creosote to mean a pesticide for use as a wood preservative meeting the American Wood Protection Association (AWPA) Standards P1/P13 and P2. The AWPA Standards require that creosote "shall be a pure coal tar product derived entirely from tar produced by the carbonization of bituminous coal."

Currently, all creosote-treated wood products—foundation and marine pilings, lumber, posts, railroad ties, timbers, and utility poles—are manufactured using this type of wood preservative. The manufacturing process can only be a pressure process under the supervision of a licensed applicator certified by the State Departments of Agriculture. No brush-on, spray, or non-pressure uses of creosote are allowed, as specified by the EPA-approved label for the use of creosote.

The use of creosote according to the AWPA Standards does not allow for mixing with other types of "creosote type" materials—such as lignite-tar creosote, oil-tar creosote, peat-tar creosote, water-gas-tar creosote, or wood-tar creosote. The AWPA Standard P3 does however, allow blending of a high-boiling petroleum oil meeting the AWPA Standard P4.

See all
User Avatar
No comments yet.