Researchers create a wooden knife much sharper than steel

Typically, when we see knives built for use in the kitchen, they're made out of metal or ceramic. Sometimes if you get food to go, you might get a knife that's made out of plastic. A group of researchers from the University of Maryland has created a knife using hardwood. The team says their hardwood knife is about three times sharper than a stainless steel dinner knife.

It was able to slice through a steak cooked medium-well without any problems. According to the first author of the paper, Teng Li, the knife can be used many times. The wooden knives can be resurfaced, which is the equivalent of sharpening steel knives with any of the various sharpening methods available. To create the wooden knife, the researchers developed a two-step hardening method.

That two-step process can increase the hardness of the knife's blade by a factor of 23. What the scientists did to get the wooden blade so sharp was ensure a higher level of cellulose was left in the wood. Typically, wood contains only about 50 percent cellulose, which is the material used to provide structural integrity for the tree. The other half of the molecules would typically be made up of weaker molecules.

The two-step process developed by the researchers allows them to remove the weaker molecules leaving only the cellulose. Next, the wood was coated in mineral oil to help protect it and maintain its sharpness during use and after washing. High-resolution microscopy was used to examine the knife to determine what enabled it to remain so strong after use.

The team found in their microscopic investigation was that the two-step process they invented prevented defects from creeping into the blade. Li pointed out that the strength of a piece of material is sensitive to and dependent on the size and density of defects such as voids, channels, or pits. The process was also used for hardening other wooden objects, including nails, making them a sharp as conventional nails.