Edited by Leon Louw
In response to the growing awareness of end consumers making more eco-sensitive choices and the resultant shifting demand by treaters for an alternative to metal-based solvent treatment products, Lonza Wood Protection introduced Vacsol Azure to the South African market as the first metal-free wood preservative in the light organic solvent sector.
Eight years later, this new generation preservative still holds full market share as the only alternative with environmental advantages over its predecessor solvent-based wood preservative products – namely TBTN, TBTO-L and PCP.
“The key attribute of promoting the use of more wood in construction is that it is a truly renewable resource which plays a vital role in reducing the carbon footprint of a building, as wood products store carbon for the duration of the product’s lifetime. But equally important to choosing wood in construction is the decision to use a metal-free, organic-based wood preservative,” says JJ du Plessis, business manager at Lonza Wood Protection South Africa.
Since the launch of Vacsol Azure in South Africa, the demand for the product has grown exponentially and du Plessis provides insight into the reasons behind its success.
“The facts speak for themselves. Vacsol Azure has achieved a solid track record of performance excellence in the organic solvent treatment segment for H2 and selected H3 hazard classes. We attribute this success to its innovative design that ticks all the boxes for treating re-manufactured, appearance, and engineered wood products where both moisture content during processing and water repellence in the end-use product are critical. As a result, the last eight years has seen Vacsol Azure become an essential component of wood preservation in the South African market,” says du Plessis.
Maintain natural colours
One of the popular features is the clear liquid preservation solution, which on application maintains the wood’s natural colour with a beautiful light honey shade. This makes it the logical choice for treating architectural features such as stairways, laminated beams, roof trusses, ceiling boards, flooring, panelling, doors, cupboards, skirting and window frames amongst others.
The solvent-based solution is another practical feature that is very appealing to treaters of engineered products and structural wood. Because the solution does not affect the wood’s moisture content, strength, dimensions or glue bonds during the treatment process, wood products can be treated in their final shape and form.
According to du Plessis, the Ecospecifier Global endorsement, and the fact that Vacsol Azure is rated among the contributing products to the achievement of the Green Building rating tool credits, have been instrumental in building product confidence – not only for their customers, but also for their customers’ customer.
Initially, Lonza launched Vacsol Azure at four treatment plants, one of which was Lamtim Products situated in the KwaZulu-Natal Midlands. Lamtim is the country’s largest specialist producer of laminated timber materials, so being one of the first treaters to use Vacsol Azure meant ensuring that the product met the company’s commitment to providing quality products to its customers.
Protection against attack
Lance Chapman, director at Lamtim Products says that Vacsol Azure gives the company the assurance that its beams will remain stable without any dimensional distortion through the treatment process and into service. “What really stands out for us is that our beams retain their natural colour. This is not only attractive, but also highly sought after. The protection against wood decay and insect attack is of the highest quality and it has environmental benefits – which is an important consideration in our company. I can honestly say that the investment made into our treatment plant with Vacsol Azure has added value to our business,” says Chapman.
The advanced protection against fungal decay, woodborers and insect attack is a result of preservative constituents made up of a synthetic pyrethroid insecticide – permethrin, and organic azole fungicides – Tebuconazole and Propiconazole. In addition, the low pressure, double vacuum treatment process drives the preservative deep into the cellular structure of the wood to provide this enhanced protection.
However, du Plessis stresses that without an effective on-site quality control management system to ensure that the correct penetration requirements are met, the quality and service life of wood treated with Vacsol Azure is compromised.
“Inadequate and non-uniform penetration for pressure processes is always a concern as it leads to failure of the product in the end-user stage. Regular and effective penetration tests are essential to ensure that the chemical has penetrated deep enough for the wood to comply to the SANS 1288 and SANS 10005 national specifications. Although the treatability of wood is related to its porous structure, it is also influenced by other parameters such as wood moisture content, drying technique, preservative formulation, and the treatment process. For this reason, our technical support team is always on hand to assist our customers in achieving the correct degree of preservation and thereby ensure the end-use performance of Vacsol Azure in the consumer market,” says du Plessis.
“Penetration testing is most important at Lamtim Products. Without testing and the support of Lonza’s technical backup, we cannot maintain our SABS certification,” comments Chapman.
The penetration test for Vacsol Azure differs from CCA and is carried out by placing samples into the charge at various points among the bundle, which can be either block stacked, or strip stacked. The wood must be below a 17% moisture content and should be in its final shape and form with all machining and rip sawing completed. It must also be free of any signs of fungal decay and insect attack and should not be treated if it has been affected by sap stain, as this results in excessive absorption of the treating solution.
Denise Conradie, quality assurance and technical manager at Lonza says that once the double-vacuum process is completed, the samples must be removed, cut open halfway and sprayed with a PAN indicator. The preferred method of applying the indicator is by spraying to get an even wetting across the surface. It is inefficient to apply so much indicator that it runs off the surface as this will result in it smearing and the dis-colouration will not present the correct penetration levels. The colour of the PAN indicator is yellow and when applied will change to red to indicate the presence of Vacsol Azure.”
Monitoring treatment plants
A penetration test is required to determine the degree of preservation, which is expressed in two ways – namely retention and penetration. The penetration is determined by measuring the depth of the red discolouration from the wood surface. The retention is calculated from the weight of preservative per cubic metre and expressed in kg/m3. Importantly, the retention level will dictate the hazard class of the treated wood.
When Vacsol Azure has been correctly applied at the stipulated concentration, the retention level should meet the required retention as per SANS specification for both H2 and H3 hazard class applications. For the treatment of selected H3 exterior above-ground applications, an additional suitable water repellent and UV resistant coating is required.
In South Africa, all wood treatment plants are monitored through a compulsory third-party product certification scheme. Sawn treated wood must display the treater permit name, the stress grade marking, the hazard class the wood has been treated to and a product certification mark of one of the approved certification bodies – either the South African Bureau of Standards (SABS), the South African Technical Auditing Services (SATAS) or African Certification and Testing (Pty) Ltd (ACT). In addition to these legislative requirements, wood treated with a preservative supplied by Lonza Wood Protection must bear the TAN trademark.
Du Plessis concludes that “through introducing Vacsol Azure to the South African market has proved to be yet another example of how listening to our customers’ needs gives Lonza the opportunity to provide wood treatment products that add value to our customers’ business and above all help to ensure that the wood preservation industry will grow well into the future.”