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black stuff for preserving wood

Creosote is wood preservative stuff which protects wood from various types of pestilential insects that eat wood. The term "Creosote" refers to the two main types of creosote: Wood Creosote and Coal Tar Creosote. Wood creosote is derived from trees of a particular type, by a process of distillation. However when people talk about "Creosote" they are usually referring to the Coal Tar Creosote which is a by-product of the Oil industry. Such creosote is black sticky oily stuff, with quite a strong smell. If you paint it on wood, the little bugglies can't abide it, and will not eat the wood. However, it's only really practical for wood that's in an outdoor setting, such as telegraph poles, railway sleepers, fenceposts, etc. Indoors it's not such a good idea, as the smell gets a bit much, and it might not be good for you.

Creosote looks a bit like old engine oil. If you have found an old can of black gunky stuff and you're wondering if it is creosote or if it's old engine oil, and you don't happen to recognise the distinctive smell, there's a sure way to tell if the stuff is oil or creosote: Put a small amount of it in water. Oil floats on water, but creosote sinks. Neither mixes with water. Creosote has a density (specific gravity) of 1.066 so it's heavier than water. However it tends to leave an oil slick on the surface.

According to the creosote entry in Wikipedia http://en.wikipedia.org/wiki/Creosote , creosote is made up of some quite distinct chemicals , and according to some other sites, the chemicals are big molecules with lots of carbon rings. However, from what I can see of the subject, creosote is somehow a leftover from the oil refining process and tends to end up with a variety of oily chemicals mixed together. This could also help to explain how such a heavy hydrocarbon can smell so strong, because it's got much lighter stuff mixed in with it.

The European Union has banned creosote! Despite the fact that it's a well tried and trusted stuff and has been in use as a wood preservative for centuries, it's now been banned. The reason appears to be some sort of perceived health risk. In lab rat experiments, rats that were painted with creosote for weeks eventually developed cancer. That's hardly surprising, and it is a matter of commonsense that you don't want to be painted in creosote for weeks. That's no reason to ban the stuff. It's yet another European-Nonsense thing where legislation is based on theory not good sense. Now if someone wanted to bring the whole European Union crashing down, it would be a simple matter of repeating the "creosote rats" experiments but using petrol instead of creosote. Petrol is also stuff which doesn't do a creature any good in prolonged exposure, and the rats would die. Bureaucrats would then have to ban petrol, which would ruin the entire economy.

If you find some old tins of creosote stashed away in your garden shed, try not to worry. The stuff didn't present a hazard to folks in the old days, and it shouldn't be any more hazardous now. The best thing to do with it is to paint it on garden fenceposts and other outdoor wood, preferably in out of the way places where people can't lob on it or smell it.

It stands to reason that creosote is toxic. By its very nature it must be. That's how it stops insects from burrowing into the wood and eating away at your timbers. Any insects that had burrowed into a fencepost would not live well after you'd applied creosote and it had soaked into the wood. The insects would be subject to prolonged exposure to creosote and that would be the end of them. You, in contrast, can wash the stuff off your hands with enough soap, and with a much lower surface area to volume, you'll survive much better.

The key is: Avoid prolonged exposure.

There have been some unfortunate cases of poisonousness affecting entire populations of some towns in the United States. The cases are billed as "creosote poisoning", but this may be a misnomer. The wood preserving businesses in those towns were using a noxious cocktail of chemicals, including arsenic, and it's far from obvious that it was the creosote that was to blame for the horrific illnesses and deaths. Also, the standard of working conditions in some of the places was deplorable, and people were eating food which had been contaminated with various chemicals, and then developed illnesses of the mouth, gut, etc. Some shocking info on this can be seen at such pages as http://gangbox.wordpress.com/2008/05/15/creosote-blues-how-bnsf-railroad-killed-its-workers-with-the-toxic-lumber-preservative/ and http://www.kvue.com/news/local/stories/110107kvuecreosote-bkm.1cc281e4a.html , but remember that there's a lot of chemicals involved, not just creosote. Crucially, long-term exposure to various chemicals is involved.

Sometimes you'll see vaguely unscientific claims made such as "mice fed a large amount of wood creosote at one time had convulsions and died". What counts as a "large" amount? Probably equivalent to a human quaffing a pint or two of creosote, with obviously expected effects. It doesn't prove anything we didn't already know. However there are more quantifiable results at such pages as www.epa.gov/IRIS/subst/0360.htm

There are also reports such as "Creosote agent slows ageing in mice" www.scienceblog.com/cms/creosote-agent-slows-aging-mice-13357.html in which mice lived longer because of wood creosote. Again, the actual test results would have to be examined.

Not to be confused with "Mr Creosote"!

Mr Creosote is a character in Monty Python's "The Meaning of Life". He is very fat, and eating a vast meal in a posh French restaurant. The scene is quite famous, as the waiter finally persuades him to eat an after-dinner mint, saying it is "only waffeur thin". After eating the mint, Mr Creosote explodes.