they would be treated with one of two things. creosote or pressure treated.
creosote the wood would be black and stink like railroad ties. Bad sht never burn it.
pressure treated wood has a green tent to it. Not positive but I think it's an arsenic based poison. Also bad sht.
What makes you think they were treated?
posted 4 years ago
Thanks for your replyDan. I assumed that they were treated in some way as they would be standing in the open in all weathers, planted in theground. Of course they are very weathered so they have no colour or smell to them now. I suppose my question should have been -- Are farm fence posts treated with chemicals (in the UK). Thanks for any advice. Patrick Knight
Location: Greybull WY north central WY zone 4 bordering on 3
posted 4 years ago
Actually there are way more treatments than those. Copper arsnic is another one. Probably the next post common one in the US is Pentachlorophenol commonly called Penta. It can be mixed with oil or water for treating the wood. Really common in treating power poles. The most common poor mans answer for treating posts was to stand them in a barrel of oil deep enough to have the part that was buried oil soaked. If you expose the base of the post you can usually see that one in the wood.
That said older fence posts stand a good chance of not being treated. There are numerous woods that are more rot resistant and often used without treatment. Red Cedar is the most common one in this area. We are fairly dry so rot is less of a problem but I am approaching 50 and I am aware of posts that looked old when I was a child so they probably are nearly 100 years old and still holding.(assuming they were put in some time in the 30 years after the area was homestead. In a wet climate the results won't be as good but the good woods untreated should still be good for a couple of decades in most cases. Osage orange, black locust, white oak, redwood are other common woods consider rot resitant and likely to be used for posts. If you can identify the wood as one that is naturally rot resistant there is less chance it will be pressure treated. Then look for dark staining in the buried zone as it is a symptom of both oil and some penta treated posts. Those are your best guess for trying to figure out of the post is treated. They are not guarantees simply the best you can do without a lab testing each post.
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