Tag Archives: ACQ

MCA: Micronized Copper Technology

Particulate (micronized or dispersed) copper preservative technology has recently been introduced in the USA and Europe. In these systems, the copper is ground to micro sized particles and suspended in water rather than being dissolved in a chemical reaction as is the case with other copper products such as ACQ and Copper Azole. There are currently two particulate copper systems in production. One system uses a quat biocide system (known as MCQ) and is a take-off of ACQ. The other uses an azole biocide (known as MCA or μCA-C) and is a take-off of Copper Azole.

Treated Wood StampProponents of the particulate copper systems make the case the particulate copper system perform as well or better than the dissolved copper systems as a wood preservative, but other industry researchers disagree. None of the particulate copper systems have been submitted to the American Wood Protection Association (AWPA) for evaluation, thus the particulate systems should not be used in applications where AWPA standards are required. However, all of the particulate copper systems have been tested and approved for building code requirements by the International Code Council (ICC). The particulate copper systems provide a lighter color than dissolved copper systems such as ACQ or copper azole.

Proponents of the micronized copper systems claim the systems are subject to third party inspection under a quality monitor program. However, the monitoring program is not subject to oversight by the American Lumber Standards Committee (ALSC) as is required for the AWPA standard systems.

Two particulate copper systems, one marketed by Osmose as MicroPro and the other as Wolmanized using μCA-C formulation, have achieved Environmentally Preferable Product (EPP) certification. The EPP certification was issued by Scientific Certifications Systems (SCS), and is based on a comparative life-cycle impact assessments with an industry standard.

The copper particle size used in the “micronized” copper products ranges from 1 to 700 nm with an average under 300 nm. Larger particles (such as actual micron-scale particles) of copper do not adequately penetrate the wood cell walls. These micronized preservatives use nano particles of copper oxide, for which there are alleged safety concerns.

A competitor of Osmose, Viance, has waged what Osmose terms as a “negative public relations campaign questioning the effect”.

Osmose President Paul A. Goydan calls the campaign, “desperate, deceptive and damaging to the entire treated wood industry, including preservative manufacturers, wood treatment companies, distributors, retailers, contractors and deck builders.”

The chemical retention level of Micronized Copper is 0.23 lb/ft3 in order to meet the IBC (International Building Code) requirement of a UC-4B for structural in ground use in post frame buildings.

East of the Rocky Mountains, MCA has become the pressure treatment of choice for one of the large “box stores” as it requires no special fasteners (unlike ACQ treatments). ACQ treatments have been found to more quickly erode fasteners in contact with the treated lumber than the former CCA, and now….MCA.

Based upon the evidence at hand…although there is not a ten year or more history of MCA use, Osmose has obtained approval by the Building Codes for their product, and I’d not think one of the largest Big Box stores in America would endorse it’s use without close scrutiny.  At this point, I would have no reservations using MCA treated lumber in any building of my own.

Pressure Treated Lumber: Copper Azole

Most of us – both those who specify wood treating and those who use it, look upon the litany of possible wood treatments like alphabet soup.

Lumber Treatment PlantOr maybe more like Scrabble – where my 19 year old daughter always seems to either draw the right letters, or make otherwise incomprehensible words (to her Dad anyway) out of a total jumble.

Copper azole preservative (denoted as CA-B and CA-C under American Wood Protection Association/AWPA standards) is a major copper based wood preservative which has come into wide use in Canada, the USA, Europe, Japan and Australia following restrictions on CCA (Chromated Copper Arsenate). Its use is governed by national and international standards, which determine the volume of preservative uptake required for a specific timber end use.

Copper azole is similar to ACQ (Alkaline Copper Quaternary – read more at https://www.hansenpolebuildings.com/blog/2012/06/acq-treated-lumber/) with the difference being the dissolved copper preservative is augmented by an azole co-biocide like Tebuconazole instead of the quat biocide used in ACQ. The azole co-biocide yields a copper azole product which is effective at lower retentions than required for equivalent ACQ performance.

Here in North America it is marketed widely under the Wolmanized brand in North America.

The AWPA standard retention for CA-B is 0.10 lb/ft3 for above ground applications (UC-3) and 0.21 lb/ft3 (pounds of pressure treating chemical retained per cubic foot of wood) for ground contact applications (UC-4A). Type C copper azole, denoted as CA-C, has been introduced under the Wolmanized brand. The AWPA standard retention for CA-C is 0.06 lb/ft3 for above ground applications and 0.15 lb/ft3 for ground contact applications. Both CA-B and CA-C require a retention of 0.31 lb/ft3 in order to meet the IBC Code requirement of a UC-4B for structural in ground use in post frame buildings.

For detailed information on pressure treated lumber for structural in ground use: https://www.hansenpolebuildings.com/blog/2012/10/pressure-treated-posts-2/

The copper azole preservative incorporates organic triazoles such as tebuconazole or propiconazole as the co-biocide, which are also used to protect food crops. The general appearance of wood treated with copper azole preservative is similar to CCA with a green coloration.

Every piece of pressure treated lumber will have a tag on it stating what treatment chemical was used and to what level it was treated.  Be sure for look for these tags.  Don’t get fooled by companies stating they use wood treated for in ground use, only to be sent lumber with inadequate treatment.  Your future question to me will be “why did my posts rot?”  With the right chemicals, and the right level of treatment, your letter will have two words, “Thank You.”