Reply To: How to be sure reclaimed wood is untreated
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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.
- This reply was modified 6 years, 4 months ago by Larry Geib.