The wooden blade is almost three times sharper than a stainless steel table knife, allowing it to cut through, for example, a steak with remarkable simplicity.
The sharpest knives on the market are made of steel or ceramic. These are both man-made materials, where the blades must be forged under extreme temperatures in ovens. That can of course be more sustainable. And so, in a new study, researchers have developed a new and above all more sustainable way to make razor-sharp knives from – yes, real – wood.
Hard materials
It is remarkable that researchers have succeeded in doing so. Just look around you. All the hard materials you use every day are probably man-made materials. That’s because natural materials don’t necessarily meet our requirements.
Ceramic knives
But these hard materials are often not very durable. “For example, the production of stainless steel is very energy-intensive,” said study leader Teng Li in an interview with Scientias.nl. “Therefore, it also has a significant and negative impact on the environment. For example, the manufacture of ceramics involves extremely high temperatures (of up to thousands of degrees Celsius). That is not the only reason why Li went looking for an alternative to ceramic knives. “Such knives are often brittle and must be handled in a special way to prevent damage,” the researcher continues. “And finally, while ceramic blades can be sharpened, it requires special tools that are often quite pricey.”
Wood
Enough reason for Li to investigate further. Because is there a way to manufacture more durable knives that still meet our requirements or even perform better than the currently widely used ones? Li aimed his arrows at wood. “Cellulose, the main component of wood, has a higher strength-to-density ratio than most engineering materials, such as ceramics, metals and polymers,” he says. “But our existing use of wood is barely reaching its full potential.”
Cellulose
Cellulose gives wood the so-called tensile strength. However, wood actually only consists of 40 to 50 percent of this component. The other two components are hemicellulose and lignin. The researchers tried to process wood in such a way that these latter weaker components were removed without affecting the cellulose skeleton. To do this, they boiled the wood in a chemical bath at 100 degrees Celsius – a temperature significantly lower than what is needed to manufacture ceramics.
Wooden knives
What came out was so-called ‘hardened wood’ from which the researchers successfully fabricated razor-sharp blades. The wooden blade is almost three times sharper than a stainless steel table knife, making it easy to cut through a medium-well-done steak, according to Li (see also the video below).
After use, the blade can be washed and reused, making it a promising alternative to disposable steel, ceramic and plastic blades.
Incidentally, knives are not the only objects that can be made from the hardened wood. The researchers have also manufactured nails that are just as sharp as conventional steel ones. But, unlike the well-known nail, the wooden variants are resistant to rusting. In an experiment, the team even managed to hammer the wooden nails through three planks without damaging them. In addition to knives and nails, Li hopes in the future to make hardwood floors that are more resistant to scratches and wear.
The wooden knives also offer a solution with a view to a future circular economy. “According to a recent study, there are more than 3 trillion mature trees on Earth,” says Li. “This translates to over 400 trees for every person in the world. In addition, trees are renewable and wood sustainable. There are fruitful opportunities for us to use commonly available materials in nature for a sustainable future. By giving natural wood even higher performance, we can explore its full potential. In any case, the opportunities emerging from this study are encouraging.”
To replace
It is possible that the wooden blades could eventually completely replace the stainless steel table knife, especially since the former cut even better. “In our kitchens, we have many pieces of wood that we use for a long time, such as a cutting board, chopsticks or a rolling pin,” Li sums up. “Wooden knives can also be used many times if you sharpen them in time and maintain them well.”
In order to actually bring the wooden knives to the market, it is now being examined whether the production time can be reduced and the chemicals used can be recycled to reduce production costs. “This will take some time and additional research and development efforts,” said Li. “But it’s definitely worth it.”