Accoya Introduces Wood Without Compromise
Against a backdrop of growing concern about the environmental impacts of the things we do and the materials we use, the popularity of wood is set to increase. Since time immemorial, mankind has made good use of wood both indoors and out. Wood is a versatile, attractive, and practical material; it is also our only naturally renewable construction resource.
When properties such as strength, beauty, and versatility are required, wood is the natural choice for many applications. However, the compelling attributes of wood are often offset by the susceptibility of many species to deterioration and degradation when used outdoors. Historically, the use of inherently durable tropical hardwoods and the application of toxic chemicals to temperate climate woods have provided partial solutions. As the availability of durable tropical hardwood diminishes and the use of toxins to improve the durability of softwoods becomes subject to increasingly restrictive legislation, the demand for an ultra-high performance, non-toxic alternative is growing.
Accoya® wood offers an outstanding solution. Accoya® wood from Titan Wood is an ultra-high performance all-natural solid wood, which has properties that surpass those of the best tropical hardwoods, yet is produced using a non-toxic process.
The technology behind Accoya® wood is based on wood acetylation, a process that has been studied by scientists around the world for more than 75 years. This method of improving wood has been proven to deliver such superior performance that it has long been used as the “gold standard” against which other methods are measured.
The physical properties of any material are determined by its chemical structure. Wood contains an abundance of chemical groups called “free hydroxyls”. Free hydroxyl groups absorb and release water according to changes in the climatic conditions to which the wood is exposed. This is the main reason why wood swells and shrinks. It is also believed that the digestion of wood by enzymes initiates at the free hydroxyl sites - which is one of the principal reasons why wood is prone to decay.
Acetylation effectively changes the free hydroxyls within the wood into acetyl groups. This is done by reacting the wood with acetic anhydride, which comes from acetic acid. When the free hydroxyl group is transformed to an acetyl group, the ability of the wood to absorb water is greatly reduced, rendering the wood more dimensionally stable and, because it is no longer digestible, extremely durable. The process of attaching acetyl to wood is complicated: controlling and measuring the attachment of acetyl while protecting the wood’s strength and beauty is difficult. With Accoya® wood, these challenges have been overcome.
The production process effectively increases the wood’s acetyl content, adding nothing to the wood that does not already naturally occur because acetyl groups are present within all wood species. In general, softwoods have an acetyl content of 0.5 to 1.5% and more durable hardwoods have an acetyl content of 2.0 to 4.5%. During the Accoya® wood production process these levels are surpassed, significantly improving the source wood’s durability and dimensional stability. Increased durability means that Accoya® wood lasts longer, helping to conserve even sustainable wood sources. Improved dimensional stability (less shrinking and swelling) means that even environmentally friendly wood coatings, such as improved paints and stains, will last longer and need to be maintained less frequently. Additionally, this extended life improves Accoya® wood’s carbon sequestration advantages and successfully contributes in the battle against global warming. Furthermore, Accoya® wood is ideal for use in window, doors, and cladding due to its reduced thermal conductivity. This results in reduced energy consumption and contributes to a minimized carbon footprint.
The by-products from the production of Accoya® wood are a small amount of valuable fertilizer, readily useable terpenes and acetic acid, which is reused thereby limiting the amount of raw materials utilized.
Production facilities follow strict processes to ensure minimal impact. Chemical preservatives (such as oil, ammonia or heavy metal compounds) improve fungi and insect resistance; however, they do not improve dimensional stability. They also risk harming living organisms by leaching into the earth and present challenges for the safe disposal of the wood at the end of its serviceable life. Accoya® wood presents none of these problems, is 100% recyclable and may be disposed of in the same way as unmodified wood. By using certified sustainably grown wood from well managed forests and improving its properties without adding toxins, Accoya® wood helps to protect threatened species, rainforests and local environments.
Accoya® Wood in Action
Accoya® wood can be used with absolute confidence and is suitable for a wide variety of applications, from the ordinary to the extraordinary.
The patio area of the prestigious London Mayfair offices of Fairfax I.S. has been decked using Accoya® wood enabling the enjoyment of the summer sun in the city. Accoya® wood decking was chosen for its beauty, durability and stability.
Accoya® wood has superb potential in structural applications where it can be used to replace traditional construction materials such as steel. In December 2006, following extensive independent research, Accoya® wood was chosen as the main construction material for two unique heavy traffic road bridges across the A7 at the city of Sneek in the Netherlands. The bridges, each measuring 20 metres high by 40 metres long, are due for completion by 2009. Accoya® wood will be laminated in large sections measuring 1080 x 1400 mm. The project marks a breakthrough in the use of durable modified wood in heavy traffic road bridge construction and the bridges will be the first of their kind in the world. Accoya® wood, with its outstanding dimensional stability, reliability and durability credentials, was the natural choice for the project.
Accoya® wood’s superior dimensional stability opens up a wide variety of applications for this ‘new wood species’. Successful trials have, for instance, been carried out in Europe for the production of the wooden combs used in harmonicas. Here, Accoya® wood is particularly valued as it will not react adversely to humidity caused by human breath.
Certain environments are particularly punishing and few are harsher than the banks of canals, where wood is used to hold back the earth. In this application the wood’s exposure to water, microbe rich soil and - most obviously at the waterline - air, is particularly challenging. In the Netherlands, canal linings were traditionally made using tropical hardwoods but, with this no longer being an option, an alternative is needed. Accoya® wood has been trialed for this purpose with excellent results. Even after 10 years in the water, exposed to all temperatures from sub-zero to the extremes of the summer sun, the Accoya® wood emerged with no discernible degradation at all.
From sundials that will be exposed to extreme temperature variations, to fun tree houses, garden furniture, signage and more; the sky is the limit with Accoya® wood. Where quality, durability, dimensional stability and reliability matter, Accoya® wood is the natural choice.
Starla Middlebrooks is Global Public Relations Manager for Titan Wood Limited in Dallas, TX. For additional information about Titan Wood products, please contact her at starla.middlebrooks@titanwood.com or visit the Accoya site at http://www.acoya.info