Copper Azole

Copper azole preservative (denoted as CA-B and CA-C under American Wood Protection Association (AWPA) standards) is a major copper based wood preservative that has come into wide use in the USA, Europe, Japan and Australia following restrictions on CCA. 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 with the difference being that the dissolved copper preservative is augmented by an Azole co-biocide instead of the quat biocide used in ACQ. The Azole co-biocide yields a Copper Azole product that is effective at much lower retentions than required for equivalent ACQ performance.

It is marketed widely under the "Wolmanized" brand in the US, and the "Tanalith" brand across Europe and other international markets.

The AWPA standard retention for CA-B is .10 pounds per cubic ft (pcf) for above ground applications and .21 pcf for ground contact applications. Type C copper azole, denoted as CA-C, has been introduced under the Wolmanized brand. The AWPA standard retention for CA-C is .06 pounds per cubic ft (pcf) for above ground applications and .15 pcf for ground contact applications.

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 colouration.


Other copper compounds
These include copper HDO (CuHDO), copper chromate, copper citrate, acid copper chromate and ammoniacal copper zinc arsenate (ACZA). The CuHDO treatment is an alternative to CCA, ACQ and CA used in Europe and in approval stages for United States and Canada. ACZA is generally used for marine applications.