• The withdrawal in 2004 of chromated copper arsenate (CCA) from the residential treated-wood market led to a spate of new preservatives such as ammoniacal copper quat (ACQ) and copper azole (CA). Both of those chemicals rely on higher concentrations of copper to pick up the slack left by the absence of chromium and arsenic. While both ACQ and CA are effective preservatives, they are also more corrosive than CCA. Briefly, copper eats steel and aluminum for lunch, and one of the benefits of the now-missing arsenic and chromium was that they made the copper less corrosive. This one-two combination caught a lot of deck builders and hardware manufacturers short, and before long, deck builders were talking about little other than failing flashing, fasteners, and hardware. The wood-treatment industry responded quickly with another generation of preservatives intended to be less corrosive. Notably, Osmose, one of the oldest and largest manufacturers of preservatives, came out with MicroPro, a micronized copper quat (MCQ) formulation. It differs from ACQ and CA mainly in how the copper is dispersed through the treatment chemical. In ACQ and CA, the copper is in an ionic form, which goes into solution easily and combines readily with other elements — which in turn is why it helps to corrode other metals. In MCQ, the copper remains in metallic form but is ground extremely finely — one micron or less — and dispersed in a suspension rather than a solution. A similar process is used to make micronized copper azole (MCA).

    Discord in the wood-treatment industry

    No one disputes that MCQ and MCA are less corrosive than ACQ and CA. However, in the summer of 2007, Charlotte, N.C.–based Viance, a preservative manufacturer that did not go the micronization route, began an advertising campaign (taking out full-page ads in Professional Deck Builder and other publications) alleging that the micronized copper formulations didn’t actually preserve wood very well. Specifically, Viance claimed research it had done at test sites in Japan and Hawaii demonstrated that off-the-shelf MicroPro treated wood showed an early susceptibility to decay. Viance also pointed out that MicroPro and other micronized copper formulations had not been approved by the American Wood Protection Association (AWPA). As one might expect, Osmose didn’t sit still for this. It responded with its own media campaign and a Web site, treatedwoodtruth.com. Osmose stated that Viance’s testing did not follow industry protocol. Additionally, Osmose pointed out that AWPA approval was only one way to gain code acceptance, and that it had simply used a different path, obtaining an ICC-ES report.

    Documented failure or not?

    The conflict ramped up in January 2009, as reported in the March/April 2009 issue of Professional Deck Builder. Viance claimed to have found in-service wood treated with micronized copper that showed signs of decay after only a few years in the ground. A report by an independent lab, Timber Products Inspection of Conyers, Ga., appeared to verify this assertion. Then, in a public letter dated February 12, 2009, Timber Products Inspection (TP) cautioned the industry not to draw broad conclusions based on its earlier report to Viance. The letter reads in part: With respect to the posts that TP tested, TP was involved from the time the posts were extracted. However, TP was not directed to, and thus did not, identify a random sampling of posts treated with MCQ for testing. The location of the posts that were included in the testing occurred prior to TP’s involvement. Thus, the posts described in the Report should not necessarily be viewed as a representative sample of MCQ posts in use at this time in the United States. There is a Subjective Element to the Grading Reflected on the Report. Since the release of the Report, TP has received a number of questions regarding the specifics of the grading used in the Report. The Report includes a description of what each number on the scale indicates. TP personnel used those descriptions in assigning numerical values to the samples. Thus, although the grades in the Report were assigned by highly-trained and experienced personnel, it is possible that other colleagues would have assigned slightly different values to the tested samples.

    Here come the lawyers

    In 2008, Osmose filed suit in federal court alleging that Viance’s claims were false and misleading. On March 20, 2009, District Court Judge Jack T. Camp granted Osmose a temporary restraining order that, among other conditions, barred Viance from claiming that the Timber Products report verified Viance’s allegations about micronized copper. The legal battle continued over the summer, and on September 29, 2009, Judge Camp issued a preliminary injunction in favor of Osmose that reads in part:

    Viance cannot claim or imply that the studies they conducted in Hawaii and Japan demonstrate that structures built using micronized copper-treated wood are unsafe, pose a threat to consumers, or are structurally unsound.

  • The in-service survey conducted by Viance and the Hawaii/Japan field stake tests do not support broad conclusions about the safety of consumers or the integrity of structures built with micronized treated wood. Such statements are literally false, and statements that Timber Products “verified” the conclusions drawn by Viance are also literally false.
  • Viance cannot claim or imply that the studies they conducted in Hawaii and Japan demonstrate that micronized copper preservatives are defective in general or are less effective than solubilized copper preservatives.
  • Viance may not indicate or imply that any conclusions or opinions stated in their advertisements concerning the effectiveness of micronized copper preservatives or the safety of structures built with micronized copper-treated wood are verified or endorsed by Timber Products.
  • Viance could not rebut the conclusion of the SCS Life-Cycle Assessment (LCA) of MicroPro (MCQ) that, when compared to ACQ, MCQ depletes fewer energy and metal resources, disrupts habitats less and results in lower greenhouse gas emissions.
  • Viance may not claim or imply that Osmose’s MicroPro process was not certified as an Environmentally Preferable Product (EPP) by SCS, or that SCS did not consider life cycle analysis including efficacy analysis in awarding EPP certification to Osmose’s MicroPro process.

According to Viance, this new ruling is less restrictive than the one issued in March. Additionally, Viance claims, “In its ruling, the Court reached no conclusion on the effectiveness of micronized copper wood preservatives or ACQ and permits Viance to continue to publish results of tests and studies on micronized copper preservatives and their performance in service.” I spoke with representatives from both Osmose and Viance about this injunction. Citing legal concerns, neither company’s spokesman would say much beyond what was already contained in their press releases. I did learn that Viance has not yet decided whether to appeal the judge’s decision, but that it does intend to continue to publish its research “within the guidelines set forth by the Court.” And Osmose continues to vigorously defend the efficacy of micronized copper and points out there are billions of board feet of MicroPro treated wood in service. The complete press releases from each company can be found here and here.

Andy Engel Editor, Professional Deck Builder