Jim Vance wrote:
I know CCA lumber is no longer being manufactured, but now we have ACO (alternative treated lumber). Does anyone know anything about this product? How much safer, if any, is it than CCA? What chemicals are used to treat it? All other wood or non-wood products are either too expensive or not easily available(cedar, redwood, cypress), or are not made for some projects (no 2X4's, 2X6's, 4X4's, etc.)
The ACQ stands for Ammoniacal Copper Quaternary. There are a couple of variants on the ACQ system. One uses ammonia as the carrier for the cupric oxide and the other/another uses an amine compound, probably ethanolamine, as the carrier. Both the quaternary ammonia compound and the copper component act as fungicides/biocides. I believe the exact treatment composition and process was/is proprietary to the manufacturers, and there appears to be some situational differences in performance between the ACQ variants. There is a fair amount of information on the Web about the ACQs, if you want to examine it. The enthusiasm for the ACQ products naturally varies somewhat in proportion to the author's financial interest in the product. Put to the choice, I'd rather have the ACQ than the CCA.
For the unaware, the Dirt Doctor took a lot of heat for his early and persistent opposition to the manufacture and use of CCA lumber. Obviously, his opposition was justified, and the heat was not; I doubt if he received many apologies from the CCA apologists. The chorus of support for CCA lumber was pretty typical of the pablum spewed by those whose profits flow from environmentally damaging practices. Except for the year, it was hard to distinguish the CCA lumber's support theme from the win-at-all-costs support for tetraethyl lead when its use in gasoline came under scrutiny.