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The Debate Over Micronized Copper Treated Lumber

Posted 25 March 2009 8:57 PM by [email protected]

There has been more discussion about the strengths and weaknesses of various types of pressure-treated lumber over the last year than the last 50. Most of the debate has centered around Micronized Copper Quaternary, or MCQ. 

Introduced in 2006, the MCQ formulation now makes ProWood up the majority of the pressure treated wood sold in the US. Unlike ACQ, a competing formula, it does not color the wood green, is much less corrosive to fasteners and can be used in direct contact with aluminum. 

For those reasons, and because it costs about the same as other common formulations, MCQ has become the preferred wood preservative among contractors and do-it-yourselfers alike. 

Plus, 6 years of field testing, building code acceptance (ICC - ES), affirmative scientific performance reviews (Forest Products Journal, Nov 2008) and a lifetime limited warranty combine to provide peace of mind to its users.

Viance LLC, the only major treated wood chemical producer that does not have the MCQ technology, has gone to great lengths over the past year to discredit MCQ. 

Osmose, Inc, the largest producer of MCQ, recently sued Viance in US District Court and won a temporary restraining order, preventing Viance from continuing their "...baseless media campaign, which has negatively impacted the credibility of the entire treated wood industry.", according to Paul Goydan, president of Osmose. For the full text go here:

The debate will continue, and in this space I will provide updates as they occur and further illumination on the issues. 


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