Wood conservation is a necessary and noble art. In itself, wood is an excellent construction material: in ample supply, often locally sourced, easy to process; its production requires little energy. But softwood will quickly deteriorate. It may rot by action of microorganisms or be eaten by insects. But there are new treatments, that render to softwood the properties of hardwood. Which means that we don’t have to log the tropical rain forest in order to cover our needs.
During the industrial revolution, demand for wood rose quickly. Telephone posts, railway sleepers, we needed them in the name of progress. But this wood needed to be conserved. Done by rather crude, and strongly polluting techniques of wood conservation. Like treatment with coal tar (creosote) or later with chrome salts. Agents that invariably end up in the environment.
But modern technology lends us methods of wood conservation without harmful environmental effects. With them, we can lend hardwood properties to softwood. If we remove knots and other weak spots, we will obtain a strong and durable material. We can reinforce that effect by gluing thin layers on top of each other – which will render us a strong material that we can bend into any form desired. An ideal material for a building trade that looks for new avenues.
From a chemical point of view, wood is particularly vulnerable because of the large number of free hydroxyl groups. These are ideal points of attack for microorganisms. But a treatment with furfuryl alcohol will result in wood conservation. This compound will impregnate the wood cells, binding to them through the application of heat, radiation and/or catalysts.
We can produce furfuryl alcohol by hydrogenation of furfural, a side product of the treatment of corn cobs or sugar cane. The substance has a low molecular weight and will therefore penetrate into the softwood. The treatment with furfuryl alcohol will render wood less vulnerable to moisture, it will swell less; the strong material will also be less susceptible to attack by insects. One of the companies employing this process is Foreco in Dalfsen (the Netherlands).
Wood conservation by acetic anhydride
In another technology, we impregnate softwood with acetic anhydride. This technology is being applied by Accsys, a company headquartered in London, with production facilities in Arnhem (the Netherlands) and Hull (UK). They use this technique for impregnation of fast-growing FSC® certified wood; in order to arrive at a construction material with better properties than ‘non-natural construction materials’ – like concrete. Materials, so they say, with a larger CO2 footprint than wood. Moreover, such materials use a lot of resources and energy. ‘Essentially, sustainable building materials produced in the biosphere (bio-cycle of the circular economy) have three huge ‘green’ benefits over techno-cycle materials:
- They are renewable (if managed well, potentially unlimited sources)
- They have a very low, possibly even negative carbon footprint
- If designed well (bio-cycle compliant additives, coatings & adhesives), they are biodegradable and/or compostable, returning nutrients back into the bio-cycle for new plants/trees.’
The technique of wood conservation employed by Accsys has a huge growth potential. According to their ow judgement, their material has better properties than other outdoor materials – markets in which they compete with the better and more expensive segments. Therefore, their global market potential is huge. Their wood products can be used both in new estates and in the refurbishment of old buildings.
Reduction of the major footprint of the building trade
Moreover, it starts to dawn on people that the building trade needs to reduce drastically its CO2 footprint. Particularly cement (and hence also concrete) production requires a lot of energy and emits much CO2. Primarily consumers are aware of the need for wood conservation – and that will reflect on the sector. Accsys’s products play into this movement. Moreover, with these products at hand, architects will no longer need to choose between performance and sustainability of a product. The properties of conserved wood are very good – with them available, we no longer need to choose for tropical hardwood or plastic construction elements.
Accsys is a fast-growing company. They guarantee the quality of their top product Accoya for fifty years when applied aboveground, and for twenty-five years for applications belowground. They can supply the product in all sorts of shapes and qualities. In many finishes, for ultimate creative freedom. The material is FSC® acknowledged and Cradle-to-Cradle (C2C) Gold-certified™. It is non-toxic and doesn’t leach synthetic compounds or chemicals.
Accoya has many applications. Decking and duckboards, façade claddings, bridges – anything in which wood can be applied. Moreover, the company sells Tricoya panels, made of chippings. Recently, the company started construction of a new factory in Kingsport, Tennessee, USA – a joint project of Accsys Technologies PLC and Eastman Chemical Company. Like the company says: ‘we combine chemistry, technology and ingenuity to make high performance wood products that are extremely durable and stable, opening new opportunities for the built environment.’
Diederik van der Hoeven