Wood is a versatile and widely-used material known for its natural beauty and structural integrity. In recent years, heat treatment has emerged as a popular method for enhancing the properties of wood and extending its service life.
In this blog post, we will delve into the fundamental aspects of heat-treated wood, exploring the process, benefits, and considerations associated with this innovative technique.
Understanding Heat Treatment of Wood
Heat treatment, also referred to as thermal modification, involves subjecting wood to controlled pyrolysis processes at temperatures around 200 degrees Celsius. This controlled heating, often carried out with minimal oxygen, aims to modify the chemistry of wood and improve its overall properties.
Today, there are reputable companies in Europe and the USA specializing in the production of heat-treated wood, catering to various industries such as decking, siding, and even saunas.
The Three Key Steps
A typical heat treatment process consists of three main steps:
- Drying,
- Heat treatment, and
- Cooling/conditioning.
Wood is a hygroscopic material that naturally absorbs and releases moisture from its environment, leading to dimensional instability. By subjecting wood to heat treatment, the hydroxyl groups responsible for dimensional instability are broken down, resulting in reduced shrinkage and swelling. This improvement in dimensional stability is one of the key advantages of heat-treated wood.
Advantages and Considerations
Heat treatment offers several benefits beyond dimensional stability. Heat-treated wood exhibits enhanced resistance against insect deterioration, particularly termites and certain microorganisms.
Additionally, the darkening of wood color during the heat treatment process provides an opportunity to mimic the appearance of more expensive tropical wood species using readily available and less expensive light-colored wood.
However, it’s important to note that heat-treated wood may experience a reduction in strength and hardness, making it less suitable for load-bearing applications.
Exploring the Results
Numerous studies have evaluated the effects of heat treatment on wood. For instance, Eastern redcedar samples subjected to heat treatment at different temperature levels showed a significant reduction in shear strength.
Similarly, hardness values of heat-treated samples were found to be 50 percent lower compared to control samples. However, researchers have discovered that compressing wood during the heat treatment process can help mitigate the adverse effects of temperature, leading to improved compression strength.
Characteristics of Heat Treated Wood
When it comes to the properties of wood, heat treated wood surpasses even the most luxurious tropical varieties. Through the process of heat treatment, all living organisms such as bugs, larvae, bacteria, mold, fungi, and their spores are effectively eliminated, resulting in exceptional durability against biological damage.
Strength and Extended Lifecycle
In the case of conifers, the heat treatment process causes the resin within the wood to evaporate. Additionally, heat treated wood exhibits remarkable resistance to wear and fire due to structural changes that enhance its robustness. Its lifecycle can extend up to 25 times longer than that of regular wood.
Stability
Heat treated wood boasts exceptional stability as a key characteristic. With an equilibrium moisture content close to zero and minimal capacity to absorb water vapor, heat treated wood remains dimensionally stable. Unlike natural wood, it does not deform or undergo structural changes such as rot, sagging, or splitting over time.
Ecology
An important aspect of heat treated wood is its ecological cleanliness and safety. The heat treatment process relies solely on temperature and water vapor, making it a chemical-free method. This ensures that heat treated wood is an environmentally friendly product.
Visual Appeal
Heat treated wood offers tremendous aesthetic potential, playing a crucial role in achieving beautiful appearances, innovative designs, and originality. It showcases a smooth surface, vibrant color, an intense shine that encompasses the entire wood surface, and a distinct and visible wooden texture.
Versatility in Interior and Exterior Spaces
Heat treated wood seamlessly integrates into both interior and exterior spaces. In interior applications, it finds its place on walls, ceilings, and floors, as well as in saunas, furnishings, and furniture. In exterior settings, heat treated wood can be utilized for building facades, yard structures like terraces and fences, and the production of joinery products such as doors, windows, and furniture.
UV Protection for Exterior Use
When exposed to exterior conditions including UV radiation and harsh weather, heat treated wood may experience tarnishing. To prevent this, it is recommended to apply a protective treatment to the wood surface that shields it from UV radiation.