How to be sure reclaimed wood is untreated
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- This topic has 5 replies, 3 voices, and was last updated 4 years, 10 months ago by Andrew Sinclair.
1 May 2018 at 6:36 pm #537980
Several times Paul has mentioned sourcing reclaimed wood from Oxford Wood Recycling for his projects. There are a number of similar companies round the country, including a couple not too far from me. But I am wondering whether they generally mix up treated and untreated timber, and if so, how you can reliably distinguish one from the other when you are picking out boards. Does anyone have any thoughts?2 May 2018 at 12:17 am #538119
Well, EU and US law require it be labeled.
But with recycled materials, often the stamps or labels are gone. Look for them anyway.
Assuming the treatment isn’t Creosote, which is impossible to miss, Treated lumber is mostly a few species of softwood. The treatment doesn’t penetrate well in hardwoods.
southern yellow pine is usually used in the Eastern US. Doug Fir and sometimes Hemlock is used in the West. The treatment doesn’t penetrate as deeply in those woods, in my experience. I have no idea what woods are used in Europe.
One issue is that you are looking for one of three or so types of treatment processes.
Until about 2003, the main treatment was CCA ( chromated copper arsenate). This was really bad stuff. If the heavy metals didn’t kill you, the arsenic would.
( fun fact. Early Mycenaean bronze used arsenic instead of tin and killed thousands of foundry workers. Good bronze, though. Achilles armor probably killed Smiths. homer described it as “bright bronze, speckled with stars” so it probably had large crytstalline impurities – possibly some of the arsenic)
CCA has a green cast that will almost always show if you get past the surface weathering, especially in the uncut ends.sometime they stained it brown, but that didn’t penetrate very deeply. Also, the highly treated stuff for ground contact was perforated at the surface for better penetration, making it readily identifiable.
The modern treatment is ACQ ( alkaline Copper Quaternary) or it’s cousin MCQ ( Microcrystaline copper quaternary) and CA (Copper Azole)
These are less toxic as long as they aren’t inhaled or used in your salad, and you wash your hands. You should be using a mask anyway considering what we now now about wood toxicity even for untreated woods if you are doing a lot of power tool cutting.
ACQ and it’s kin work by making the wood highly alkaline and unpalatable to fungus and bugs. They also usually a green cast near the surface, where most of the chemical is.
Also, since they are caustic, any untreated nails or screws ( even stainless) will rust readily.
While not an exclusive test, you could just use some litmus paper on wet wood, and if it’s green in the first 1/8” or so or above PH 7, don’t buy it.
In my experience untreated lumber doesn’t exhibit marked changes in color in the sapwood, or any green cast ( except, of course Tulip Poplar, which I’ve never seen as treated lumber.
2 May 2018 at 6:21 am #538228
- This reply was modified 5 years, 1 month ago by Larry Geib.
Wow, that post is a mine of information about the different treatments. And a fascinating story about Mycenaean Bronze. Thank you Larry!
Does anyone who has used wood recycling companies know whether they try to sort the wood themselves?2 May 2018 at 8:04 pm #538713
Here in Oregon lots of wood recycling from construction demolition gets recycled for chipboard at large plants. The garbage transfer stations will accept it, nails and all, for a fee lower than the landfill fee by the ton. ($35 vs $95 a ton) They don’t accept treated lumber and that stuff goes to the landfill. They grouse about old painted wood also. While they accept small quantities, they don’t like the probable lead content in paint made before 1978.
And I can put wood shavings in with my yard debris pickup amd they don’t grouse. I age it a little in a bin outside first, which reduces the volume. One speck of paint or green and they won’t take it, though, and for that reason any tulip poplar shavings from my planer go in the trash also.
Here’s the guidelines from the regional government, Metro, which deals with transportation, sewage,garbage landfills, recycling, bridges, and the Port of Portland in Oregon and Washington.
And the closest recycler to me ( about a mile) does accept and resell treated lumber. They stack it separately.
The second closest place just opened a couple months ago and deals in HUGE beams and slabs ( some over 100 years old first growth from closed down sawmills)
they don’t accept treated lumber.
No idea about the UK. Ask.30 July 2018 at 11:49 am #549686
I wrote to Oxford Wood Recycling to ask how they deal with treated timber. Their answer was that they don’t separate it, but that with the exception of 4×4 fence posts and 6×1 gravel boards, there is unlikely in practice to be any treated wood in their stock, and that coming across CCA is highly unlikely.13 August 2018 at 4:54 am #550153
Thanks for following up with an update Ben.
In general I think this is an important issue when using timber destined for the building trade or reclaimed from it.
Arguably one should be more careful in less developed countries than the EU/US: their OHS standards are usually lower and the climate often renders wood more vulnerable to pests (e.g. the tropics), so its more likely to be heavily treated. I believe that in Australia fence posts can still be treated with the arsenic compound for instance – and it’s hardly 3rd world.
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