Wood is an amazing material to use around the house, both for its green credentials and the way it looks and feels. That said, as a natural product there are a lot of microorganisms and insects around that would love to take a few good nibbles out of said wood, no matter whether it’s used for fencing, garden furniture or something else. For fencing in particular wood treatments are therefore applied that seek to deter or actively inhibit these organisms, but as the UK bloke over at the [Rag ‘n’ Bone Brown] YouTube channel found out last year, merely slapping on a coating of wood preserver may actually make things worse.
For the experiment three tests were set up, each with an untreated, self-treated and two pressure treated (tanalized) sections. Of the pressure treated wood one had a fresh cut on the exposed side, with each of the three tests focusing on a different scenario.
After three years of these wood cuts having been exposed to being either partially buried in soil, laid on the long side or tossed in a bucket, all while soaking up the splendid wonders of British weather, the results were rather surprising and somewhat confusing. The self-treated wood actually fared worse than the untreated wood, while the pressure treated wood did much better, but as a comment by [davidwx9285] on the video notes, there are many questions regarding how well the pressure treatment is performed.
While the self-treatment gets you generally only a surface coating of the – usually copper-based – compound, the vacuum pressure treatment’s effectiveness depends on how deep the preservative has penetrated, which renders some treated wood unsuitable for being buried in the ground. Along with these factors the video correctly identifies the issue of grain density, which is why hardwoods resist decay much better than e.g. pine. Ultimately it’s quite clear that ‘simply put on a wood preserver’ isn’t quite the magical bullet that it may have seemed to some.
1 part boiled linseed oil
1 part pure boiled pine tar
1 part turpentine
Mix until it’s homogenized, mix before use, keep in an air tight container.
Keep applying to wood until the wood can’t soak in anymore.
This must be done in a dry, warm environment.
This works best with coniferous wood.
When I was a kid my Dad only used locust for fenceposts — they lastest 20 years in the ground. black walnut was almost as good if you only used the heartwood.
My uncle owned a house in the woods in Wisconson USA. The wood of choice for fenceposts etc. was eastern red cedar (aromatic cedar) which would last up to 50 years. One of the neighbors had a huge stand of the trees on his property and would occasionally log out portions to sell to the state for their highway sign posts.
Yea pressure treated stands up and its fairly inexpensive… good thing we have been using it since the 1930’s (well more realistically since post ww2) who would have thunk
Missed the old school DIY treatment (leaving one end of the board in your engine oil drain pan for a few weeks until it soaks up through the whole thing via capillary action). But that’s understandable, it’s not great to use those in the garden.
In Australia we just use Ironbark wood. A 300 x 300 x 4500 mm post will cost you about USD $1000.
I remember when arsenic treated wood were common for their long life and rot resistance but it’s been discontinued due to health risk. Old outdoor playground and some houses may have used those wood
They still have it for “agricultural” use. I bought some fence posts treated that way a while back.
arsenic was still standard in the early 2000s
Do it the Japanese way and char the outside. Ever wonder why partially burnt trees stick around for decades after a forest fire?
I’ve used this on fenceposts for the below-ground portion, still sound after 50 years in the ground.
We protected the endgrain of the posts, too, to prevent water penetration, with typical drying oils.
I have Lowes “treated” wood that is 5 years old and rotting. NOT in ground contact!(a ramp)
The crap they sell is almost worthless now.
Treated wood sold at Lowes comes in two versions with different percentages of copper, only one of which is rated for ground contact. The stuff for above ground has about half the copper content of the ground rated wood. And both are low density soft wood that is inherently not very durable, They use that soft wood because anything more dense wouldn’t accept enough copper even under pressure, and even then the wood has punctures to aid the absorption of copper.
If I remember correctly, only the 4×4 and larger get the additional copper. If you built with 2x4s, yes … it’s crap. Actually, both grades are because of the soft wood they use.
I’d question whether his test is a large enough sample to avoid statistical noise. I’ve had two ends of a fence panel and one rot whilst the other didn’t. There’s a lot of uncontrolled factors here – Bugs, temperature, moisture, movement, soil type (which can vary a lot over a short distance in the typical UK garden just due to bits of rock in it), …
Yeah, he mentions that in the video, also how he didn’t take wood grain into account.
Unfortunately these are years-long experiments, so getting new results would take a while :)
I remember the original version of this video. Nice to see a follow-up!
Interesting that this left out torification as a treatment. I just picked up a some torified ash because I want to use it for outdoor furniture type things and don’t care for the pressure treated pine look. Right now, the Emerald Ash Borer is forcing many people to cut down their ash trees and has created quite a glut of ash lumber. Rather than make firewood out of it. It’s still much more profitable to torify it and it is a very rot-resistant and chemical free process. It’s just much more expensive to do this relative to pressure treating.
In the USA a lot of the pressure treated wood is green – never dried in a steam kill (kiln). This is why it is so darn heavy. And pressure treated means submerged in a chamber that is evacuated to pull air out of the wood, like removing bubbles from resins. I don’t know how hot it is. When the wood is wet, the penetration is low. Dried wood down at say 18% moisture gets much better penetration.
However, I would try the other DIY treatment. Use dried wood and soak the ends in a mixture of glycol based anti-freeze and borax/boric acid. You can also paint the entire length with it to stop boring insects. There are various recipes on the web. There is probably not enough anti-freeze in the wood to damage the livers of animals, but keep that in mind when it comes to the application.
Checking my memory, the Google AI summary produced two results to slightly different versions of a question on the origin of Wolmanized wood.
“Wolmanized wood treatment was invented by chemist Sonti Kamesam in the 1930s while working at the Forest Research Institute in India.”
and “The Wolmanized pressure treatment was not invented in the US, but in Germany by Dr. Karl Wolman. The Wolman Wood Preserving Company was founded in Germany in 1911.”
Fascinating, Captain.
What’s wrong with good old TAR for the underground portions of the lumber?
I built a ramp that had no ground contact for my shed so I could get my tractor loaded. That wood is falling apart barely 7 years after installation. Pressure treated and crap.
how about a nice oil based paint?