South Africa-based wood-preservative chemicals supplier Dolphin Bay Chemicals implemented its first pilot wood treatment of wood ammonium copper quaternary (ACQ) in October 2013.

ACQ was developed in the US and is being manufactured locally by Dolphin Bay Chemicals under its Permacure brand.

As the only ACQ manufacturer in Africa, Dolphin Bay Chemicals is also one of only two companies on the continent that manufacture chromated copper arsenate (CCA), one of the world’s most popular wood preservatives.

“ACQ is an alternative to and not a replacement for CCA. The availability of Permacure ACQ in South Africa creates new opportunities for timber-treatment companies to expand by offering a new product and broadening their markets. This [is an indicator] that the South African industry is maturing by diversifying into the manufacturing of new products, which is a sign of a healthy industry,” notes Dolphin Bay MD Bertus Coetzee.

CCA uses copper as a primary fungicide, arsenic as a secondary fungicide as well as an insecticide, and chromium as a fixative. ACQ also contains copper as a fungicide, but contains a quaternary ammonium compound as an insecticide, which augments the fungicidal treatment, making ACQ more biodegradable than CCA, he says, adding that ACQ is also more sustainable, as it uses fewer derivatives, such as ferrochrome and arsenic acid, obtained from the mining industry.

Like CCA, ACQ liquid is impregnated into wood by vacuum pressure at timber-treatment plants. ACQ and CCA manufacturing costs are similar, but a higher volume of ACQ is required for wood treatment, making it more expensive to apply and increasing the price of the treated timber.

Dolphin Bay Chemicals supplies two brands of Permacure ACQ – Permacure ACQ 223 and Permacure ACQ 224 – for use on timber structures such as decking, roofing and walkways.

Permacure ACQ 223 has two active ingredients – copper and alkyldimethylbenzylammonium chloride (Adbac). Permacure ACQ 224 contains copper and didecyldimethylammonium chloride (DDAC) as its active ingredients.

The copper in each brand and in Permacure CCA functions as a bactericide and fungicide, allowing for the treated wood to resist a biological attack by, for example, wood-destroying fungi such as brown rot and white rot, as well as insects such as termites and other wood borers. The pressure impregnation of the bivalent copper into the timber allows for the preservative to bond to the cellulose and hemicellulose in the wood.

The quaternary ammonium salts, Adbac and DDAC, act not only as a biocide that increases the tolerance of treated timber to copper-resistant bacteria and fungi but also as an insecticide.

A quaternary ammonium salt is a compound in which the number of bonds to a central nitrogen atom is four instead of three, leading to a positively charged ion balanced by the chloride anion.

These quaternary ammonium salts also bond to cellulose in the wood and stimulate a reaction during which the bivalent copper ions bonds to the cellulose structure and free hydroxyls in the wood. The actions of the copper and the quaternary salts results in Permacure ACQ being an effective and environment-friendly wood preservative, says Coetzee.

Market Opportunities
Coetzee says new markets that are available to timber-treatment companies offering ACQ include North America and Europe, as well as countries such as Japan, where many customers have a strong preference for ACQ-treated timber, as it is considered to be more environment friendly and sustainable.

Also, African countries, such as Cameroon and Mauritius, where the importation of treated wood is allowed, offer attractive market opportunities.

South African consumers who regard the use of ACQ-treated timber as an opportunity to enhance their green credentials offer a local market opportunity.

In addition, Dolphin Bay is exploring export opportunities for Permacure ACQ to Cameroon, Ethiopia and the East Islands, off the coast of Africa, Mauritius, Madagascar and the Seychelles.

ACQ Standards
Working with the US Environmental Protection Agency (EPA), the American timber industry developed ACQ as an alternative product for consumers who were concerned about using arsenic and chromium in CCA. The EPA, however, did not conclude that CCA-treated wood structures posed an unacceptable risk.

In line with international developments, Dolphin Bay Chemicals registered its own ACQ formula with the Department of Agriculture, Forestry and Fisheries (DAFF) in 2011 and began local manufacturing of the product in July last year.

Coetzee explains that the registration process with the DAFF involved the submission of technical data consisting of field trials, toxicology reports, stability tests and efficacy data.

He adds that Permacure ACQ complies with SANS 10005, which, in turn, complies with the American Wood Preservatives Standards p28-11/P29 and Australian Standards 1 604.1.

Creating ACQ Capabilities
Through its extensive on-site customer support, Dolphin Bay Chemicals will assist its timber-treatment customers in preparing their plants for the use of Permacure ACQ. Dolphin Bay Chemicals helped a company in the Western Cape, in October last year, and another company in the Eastern Cape is already compatible.

“This is a low-cost operation involving relatively minor adjustments to a plant. We are not simply a supplier of products – we have a high level of technical expertise and provide customers with a wide range of on-site support,” Coetzee says.

He adds that Dolphin Bay Chemicals developed the process to be as close to those that operators currently use. “There is not much that needs to be adjusted at existing plants that comply with SANS 10005 and we have adapted our training programme for easy implementation.”

However, to use ACQ, a plant must replace some of the seals and must replace all its brass fixtures. This is due to the alkaline nature of the preservative, which has a pH level of between 10 and 11. Traditional timber preservatives are water-based, with a pH level of about two, which classifies it as an acid.

Permacure ACQ can be used for wood in hazard classes H2 to H5, with H2 signifying low exposure to the elements and weathering, and H5 signifying high exposure, according to South African National Standards.

“Customers need not be concerned that the finished appearance of CCA- and ACQ-treated timber will be different,” says Coetzee, adding that while the CCA liquid has a brownish colour and the ACQ liquid a bluish colour, the CCA- and ACQ-treated timber both have a greenish tint.

Although CCA and ACQ are odour- less, ACQ has a more corrosive effect on metal fasteners than CCA and, therefore, galvanised metal fasteners need to be used when ACQ-treated timber is used for construction.