What types of treated wood are replacing CCA?
The common generic names for American Wood-Preservers’ Association (AWPA) listed treatments available today are Copper Azole and ACQ. There are two variations of copper azole, Type A and Type B. These two formulations differ in that the Type B contains no borates. For ACQ, AWPA lists ACQ-A, ACQ-B, ACQ-C, and ACQ-D. These formulations vary by the type and quantity of quaternary compound in the formula as well the use of an amine or ammonia solvent. Most of these quaternary compounds used (BAC, DDAC) contain chloride ions that can be highly corrosive to steel. Does treated wood have to undergo testing before it is sold? Corrosion tests are recommended in the AWPA evaluation process to list a preservative system in the AWPA book of Standards. Arch Wood Protection has submitted AWPA E12 Corrosion Tests on both copper azole Type A and B for committee consideration. These tests showed that corrosion rates of Natural SelectÔ (CBA-A and CA-B) treated wood as well as CCA treated wood, in contac
