Modified wood: hard as stone and transparent as glass
Modified wood: hard as stone and transparent as glass.
Natural wood without special protection is a very vulnerable building material. It is spoiled by moisture, fungi, ultraviolet rays, and other external influences. But with appropriate technological protection and hardening, it can be made a strong, resistant and, therefore, widely applicable material. We are talking about the so-called modified wood, which has incredible potential in construction and architecture.
For reference
As you know, 60% of the territory of Slovenia is covered with forests. Slovenia is the third country in Europe in terms of timber reserves. According to the Forest Institute, the timber stock in Slovenian forests is 352 million cubic meters. Of the total species composition in Slovenian forests, spruce occupies 30%, and beech 32%.
About the possibilities
It is becoming increasingly clear that the future of building and finishing our homes should be based on natural materials that do not have a negative impact on the environment and people. For example, timber buildings are easy to design, environmentally friendly, sustainable, can be recycled at end-of-life, and can also be used, for example, to generate energy.
However, with all these advantages, wood also has disadvantages: it is sensitive to moisture, UV damage, unstable in size, has a fairly soft surface and is prone to damage from pests. Of course, these shortcomings do not prevent us from using wood for the most daring projects. It just needs to be properly protected or modified.
About modification
Modification is one of the most modern methods of wood protection. It is the process of changing the molecular structure of wood pulp so that it is deeply protected from pests and dimensional instability. The most common chemical and thermal modifications, where the first is a reaction between the reagent and wood polymers, and the second heats the wood in special chambers at a temperature of 160 to 260 degrees Celsius, which is somewhat reminiscent of the traditional technique of firing stakes in vineyards or heating tiles in hot oil.
About the benefits
The main advantages of modified wood are, in addition to greater resistance to wood pests, lower equilibrium moisture content (less absorption of liquid water and moisture from the air), improved dimensional stability (up to 50% reduction in swelling and shrinkage of wood), exotic appearance and uniform color throughout the cross section. wooden element.
Thermally treated wood is durable even when used outdoors without additional protection. For example, modified spruce wood is comparable in durability to untreated Siberian larch, which means that with a relatively simple technological process and available wood species, we can to a certain extent replace another, less common type of wood.
About the wood compaction
The modification takes wood compaction one step further, allowing the wood to become more durable and easily replace steel, concrete and similar materials. Compacted wood is obtained by chemical or mechanical means. With chemical treatment, its strength increases 11 times, and with heat treatment, it triples.
The wood compaction process is being intensively studied at the InnoRenew Institute in Izola.
Researcher and architect Eva Prelovšek Niemela puts it this way: “Wood compaction is one of the wood modifications that we are actively studying in our laboratory. The wood is pressed under the influence of heat in a press, which improves its mechanical properties. It becomes very hard and the surface is very stable.
We have developed a way to keep the wood in a compact state and we already have a European patent in this area. On our site you can see one of the products that we make in our carpentry workshop. These are grilles on convector boxes, where we replaced the metal with compacted wood. We believe that compacted wood can be used for the same purposes as metal, ceramic or stone.”
About the transparent tree
However, the possible wood modifications do not end there. Mention should be made of translucent/transparent wood composites, which are not yet on the market.
In the near future, thanks to modification, it will certainly be possible to buy translucent wood, which is produced by removing all light-absorbing components (mainly lignin) from wood and replacing them with refractive-index polymers.
Transparent wood will transform architecture, because it can be used to make transparent wooden structures or window frames. All future buildings will be much more energy efficient because wood is known to be a much better insulating material than glass.
With the development and wider application of modification technologies, wood protected in this way will also become more affordable, as current prices per cubic meter can be twice or more than untreated wood. Because of this, it is not yet interesting for large projects. Now it can be successfully used on a smaller scale – for the production of facade coverings, fences, garden furniture and roofing, as well as modified wood is perfect for the production of joinery and saunas.
Sources:
https://www.tvambienti.si/01/11/2022/modificiran-les-trden-kot-kamen-prozoren-kot-steklo/
https://www.spiritslovenia.si/resources/files/2019/2019_11_SPIRIT_LES_220x275_web.pdf
