Wood preservatives are classified as biocidal Product Type 8 under the Biocidal Products Regulation (BPR) and must be approved through the BPR authorisation process before being placed on the market. The European Biocidal Products Regulation (EU BPR) came into force in 2013. All biocidal products placed on the market across EU member states must comply with this regulation, and the active substances contained in each biocidal product must also be approved or under review. Following Great Britain’s withdrawal from the EU, GB Biocidal Products Regulation (GB BPR) is now also in force and overseen by the UK Health & Safety Executive.
A new wood preservative product can be used by treatment plants in the country in which it has been authorised under BPR. If I take Tanasote S40 as an example, Arxada’s copper-oil alternative to creosote. Tanasote has been authorised across EU member states since 2021, but only received authorisation under GB BPR in February 2024. Prior to this authorisation, timber treated with Tanasote could be sold in Great Britain but treaters couldn’t treat timber with it. Before treated wood is sold on the GB market it must be ensured that the active substances are approved for Product Type 8 for the required use.
The BPR authorisation process is a rigorous risk assessment of the active substance, the formulated product and how it is used in practise. Biocidal products are evaluated in several areas; chemical properties, efficacy, risk to human health and risk to the environment are all considered. The thorough evaluation results are published in a document called the Product Assessment Report (PAR) showing the approved uses.
EVIDENCING PERFORMANCE
Any new wood preservative formulation must demonstrate its performance before being placed on the market. From a statutory perspective, the new formulation is subjected to specific laboratory and field testing.
In the development of new products across Europe, wood preservatives are tested in accordance with the requirements of EN599-1:2009 + A1:2013 and EN 252. Some test standards require the testing of both softwood and hardwoods, depending on the organism under test and the markets that the wood preservative has been designed to serve.
Wood preservative manufacturers can choose to challenge the product further by engaging in field testing in parts of the world where conditions for decay are particularly aggressive and/or by using differing test methods to further accelerate the decay of wood. The Fahlstrom stake test method is one such example of this.
A highly accelerated approach to determine decay in a real-world environment, the Fahlstrom stake test utilises thin stakes in ground contact. To help bring this to life, I again refer to the development of Tanasote S40. In addition to the testing required under the standards, Arxada invested in the Fahlstrom stake test method due to the high performance industrial timbers that Tanasote has been designed for – railway sleepers and utility poles. The combination of a very small size and harsh conditions at the aggressive, high humidity field site in Florida, has enabled us to evaluate the long-term performance of Tanasote-treated timber compared with CCA as the reference preservative. In this testing we went beyond the standard CCA retention to demonstrate performance against preservative retention known to deliver a service life of 40 years.
INNOVATING DECARBONISATION
Driving decarbonisation is key to the future of wood protection technologies. Correctly specified timber helps reduce embodied carbon over the lifetime of a build. Often this will mean that the right kind of wood preservation needs to be procured. In the development of new wood preservatives, the industry is looking at ways to reduce the carbon footprint even further – from manufacture of the wood preservative, through to how it is delivered to customers and how it contributes to waste at end-of-life.
Arxada’s drive to utilise modern chemistry to help the many sectors that specify timber advance their sustainability goals, is brought to life in the commercialisation of Tanalith MF. Ideal for sensitive environments, being both metal-free and VOC-free, timber treated with Tanalith MF can be reused or recycled at end-of-life. To further help reduce waste and fuel emissions in transportation, the wood preservative is supplied to timber treaters as a concentrate in recycled Intermediate Bulk Containers (IBC’s), which can be reused. The timber treater dilutes the Tanalith MF concentrate with water on-site, which eradicates the need of bulk tanker transportation.
ADOPTION OF A NEW PRESERVATIVE
Once a wood preservative product has BPR authorisation, the next challenge is to get the market to adopt this new formulation. Over the years, I have worked on numerous BPR authorisations and I understand that case studies and independent endorsements help to bring the BPR data to life. Commercial trials in a real-world environment are helpful to the launch of any new wood preservative.
Drawing on my recent experience with Tanasote, in addition to the advanced testing, Arxada also invested in commercial trials of Tanasote-treated timber. We have engaged in both equestrian and livestock fencing trials since 2018 to show how Tanasote-treated fencing can be used across these sectors. We have worked with the telecommunications industry on a utility pole field study, where treated timber corrosivity, climbability and conductivity were assessed, plus extensive trials with rail operators across Europe.
