SCIENCE
Densifying lumber can increase its strength tenfold. (Popular Mechanics)
Learn more about this eco-friendly renewable resource here.
Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

Photograph by David Boyer, National Geographic
Discussion Ideas
- How have scientists created a “super wood” that is stronger and more durable than metal? Read through the great Popular Mechanics article for some help.
- densification. Researchers used an innovative two-step process to increase the wood’s density.
- First, scientists boiled different types of wood—oak, poplar, basswood, cedar, and pine—in a solution of sodium hydroxide and sodium sulfite for seven hours.
- That treatment left the wood’s starchy cellulose mostly intact, but created more hollow space in the structure by removing components such as lignin, a substance that makes wood rigid and brown—what Popular Mechanics says “makes wood wood.”
- Second, scientists pressed the block at 100° Celsius (212° Fahrenheit) in a process Nature likens to making “a panini sandwich.”
- The process compresses the cellulose and shrinks the size of the wood, making it one-fifth its original thickness. It also removes defects like holes and knots.
- The densified wood is 11.5 times stronger than untreated wood.
- Other methods of densifying wood include applying higher temperatures, steaming the wood before treatment, and applying resins.
- First, scientists boiled different types of wood—oak, poplar, basswood, cedar, and pine—in a solution of sodium hydroxide and sodium sulfite for seven hours.
- densification. Researchers used an innovative two-step process to increase the wood’s density.
- How did researchers test the densified wood’s strength? Take a look at the video above for some help.
- They fired a gun! Three millimeters of the densified wood was able to halt a 46-gram steel projectile traveling at roughly 30 meters (98 feet) per second. Researchers compare this speed to the speed at which a car might be moving before a collision.
- Researchers also tested the “scratch resistance” of the densified wood using a “linear reciprocating tribometer”, a diamond-tipped device that tests the hardness of a substance.
- Other tests measured the densified wood’s ability to withstand moisture and the energy absorbed during the substance’s fracture.
- The Nature article suggests densification could make wood an eco-friendly alternative to plastics. How would this eco-friendly material be classified? Read through our short article or reference resource for some help.
- Wood is biomass. Biomass simply describes living (or once-living) things and the energy contained within them. Other sources of biomass used as renewable resources include algae, crops, and solid waste.
- How might densified wood be used?
TEACHERS TOOLKIT
Popular Mechanics: New Chemical Treatment Makes ‘Super Wood’ That Could Replace Steel
Nature: Crushed wood is stronger than steel
Nat Geo: Truly Alternative Energies: Biopower
Nat Geo: What is biomass energy?
(extra credit!) Nature: Processing bulk natural wood into a high-performance structural material