Reply #6: What I know about ACQ lumber in this case... [View All]

[jmowreader]

It's safe to use for children's play structures.

In the OLD days--say, before 2004--CCA lumber was what we had. It contained copper, chromium and arsenic. The arsenic got all thebad press, but the chromium was what was really bad for you.

These days, you can run into one of three treatments:

ACQ: Alkaline Copper Quaternary (or Ammoniacal Copper Quaternary--same thing) contains copper oxide, quaternium 60 and sodium carbonate. Copper oxide is basically edible, quaternium 60 is perfectly safe for skin contact (it's the most common preservative found in cosmetics--I figure if you can put the stuff on your face, at a higher concentration than you'd see in lumber, and leave it there for fifteen or sixteen hours like you do if you wear makeup, it's okay to put your hand on it for a little while), and there's not much sodium carbonate in the soup--it's there just to adjust pH levels.

CA/CBA: Copper Boric Azole contains copper oxide, boric acid and tebuconazole. Boric acid is used as eyewash and tebuconazole is a fungicide used on many food crops.

Micronized Copper Quaternary: This is the pressure-treated lumber that doesn't LOOK like pressure-treated lumber. It's basically ACQ, but the copper is ground finer and doesn't impart the "PT Look" to the wood. Still safe to be around, though. Brand is "ProWood."

Also note: You can use either ACQ, MCQ or CBA when building beds for organic vegetables.