Scientists create a wooden knife three times sharper than a steel blade

I’ve been to enough fairs and foodie festivals to know the wooden knife and fork you get with your semi-hot duck fries are dismal excuses for cutlery. They’re good at moving food around a plate, but that’s really it. The plastic sometimes works a little better, but that’s not great for the planet. And then there’s the knives made from frozen human feces? Don’t get me started on how poorly those cut through meat.

The gold standard for knives is usually steel or ceramics, but in a new study, appearing in the journal Matter on Oct. 20, material scientists describe their latest creation: A “hardened wood knife” around three times sharper than a stainless steel dinner knife. It can “easily” cut through a medium-well done steak, according to Teng Li, a materials scientist at the University of Maryland and first author on the paper, and can be used and reused many times. 

“In our kitchen, we have many wood pieces that we use for a very long time, like a cutting board, chopsticks, or a rolling pin,” Li said in a statement. “These knives, too, can be used many times if you resurface them, sharpen them, and perform the same regular upkeep.”  

Using wood for cutlery isn’t a new idea — the foodie festivals will tell you that much — but Li’s team developed a two-step method for hardening the wood in their knives that increased the blade’s hardness 23-fold. This was achieved by ensuring the wood retained a higher level of cellulose. 

Typically, wood contains only about 50% cellulose, which provides some structural integrity, and weaker molecules make up the rest. Li’s two-step process was able to remove these weaker components but retain the cellulose. Coating the wood in mineral oil helps protect its sharpness during use and washing.

Using a high-resolution microscope, Li’s team examined the wooden knife to determine why it was retaining so much strength. They discovered the two-step process the used prevented defects from creeping in. “The strength of a piece of material is very sensitive to the size and density of defects, like voids, channels, or pits,” he said in a statement. 

The team didn’t stop at hardened wooden knives, either. They also developed wooden nails, showing they were as sharp as conventional steel nails.

The knife’s function is impressive, but its manufacturing process could also be important. The team writes that it could be a “renewable and low-cost alternative” with “the potential to replace plastic table utensils.”