The concept of transparent wood, as improbable as that sounds, is one that scientists have been pursuing for some time. Why? Because, compared to glass, wood is stronger (it won’t shatter from impact with an object) and, as such, is appealing to home builders. Despite these efforts, transparent wood is not readily available because the conventional method of making it has a number of downsides.

The current process, using chemicals to remove the lignin (a polymer that provides rigidity and, along with cellulose, forms the woody cell walls of plants and the cementing between them) takes a long time and produces a significant amount of liquid waste that actually weakens the wood.Schematic illustration of fabricating transparent wood and demonstration of its patterning. Source: Science Advances (2021).

Researchers from the University of Maryland have developed what they believe is a better method for producing transparent wood, one that does not require removing the lignin. Instead, they removed the lignin molecules involved in producing the wood color.

The new process begins with the application of hydrogen peroxide to the wood surface. Next, the treated wood is exposed either to UV light or to natural sunlight and then it is cleaned by soaking in ethanol. Lastly, the researchers made the wood smooth by applying clear epoxy to fill the pores.

This process yielded wood that allowed 90% of light to pass through it and was found to be 50 times stronger than the transparent wood created the conventional way. The new transparent wood was also stronger and lighter than glass and provided better insulation, making it useful for both windows and roofs. The researchers added that it can also be used to build load-bearing walls.

Other potential applications include touch-sensitive displays in harsh environments and inside cars. According to the researchers, their process is clean and can be scaled for use in large buildings.

The paper is published in Science Advances.