Plant Cuttings

As much as I try to offer variety in the posts on this site, there’s one topic that I keep returning to, wood. The utility of this natural product to humanity never ceases to amaze me (and others, e.g., Mahiar Max Hamedi et al. (2025), who go so far as declaring that “Wood and Cellulose Civilized Man”. Wood is good, and well worth talking about. And that’s something that bears repeating. Accordingly, this week’s post revisits a topic from 2024 with a sort of update.

Transparent wood

This image, of “Three different sizes of balsa wood stock”, by Zach Vesoulis, is in the public domain.

From a wooden object that is out of sight [see previous post] to Earth-bound wood that’s also unseen, engineered transparent wood [ETW]. Previously looked at on this blog here, ETW has many potential applications, e.g., as “a sustainable replacement for glass which is environmentally unfriendly in its manufacture and application” (Thabisile Brightwell Jele et al., 2023), and applications such as solar cells (Steve Joseph Fonash & S Ashok), screens, windows, and luminescent and decorative materials.

By way of an update to that story, we are advised by Joseph Shavit that “Transparent wood made from egg whites and rice offers a biodegradable, energy-efficient alternative to plastic and glass”. This represents an important development from the version of ETW discussed in this blog’s earlier post, whose production “involved chemicals like epoxy, which aren’t biodegradable” (Joseph Shavit).

Although, at the time of penning this post, details of this innovative use of egg whites and rice had not yet been published in a scientific journal, it was transmitted orally at the spring meeting of the American Chemical Society (ACS), from 23^rd to 27^th March 2025 in San Diego, California. The abstract tells us that the work was presented by Bharat Baruah, a professor of chemistry at Kennesaw State University, The text of the abstract – with the title, “Fabrication of transparent wood from by impregnating voids in delignified wood and possible application in energy efficiency and electrical devices” – is a little short on details, but a press release (Lucas Downey) from the ACS gives us useful additional information (e.g., the work was carried out in collaboration with Ridham Raval, one of Baruah’s students). And, the in-depth scicomm article by Joseph Shavit provides even more information and detail.

To create Baruah & Raval‘s version of ETW, the lignin and hemicellulose from pieces of balsa [Ochroma pyramidale]* wood were removed using a vacuum chamber and sodium sulfite (a delignifying agent used in the sulfite process to remove lignin from woodpulp), sodium hydroxide (Jessica Clifton) (a version of lye that helps separate lignin from cellulose), and diluted bleach (Thomas Benzoni & Jason D Hatcher, 2023) (which is used in the “chemical processing of wood pulp to lighten its color and whiten the pulp” by breaking-down the lignin). The cellulose (Roger M Rowell et al., 2012; Maria Temming)-bounded pores that remained of the original wood were refilled by soaking them in an egg white and rice extract mixture**, along with a curing agent (Vincent Makala; Jerry Xie) called diethylenetriamine to keep the material see-through (from the Press Release). The result is a flexible, durable, semi-transparent wood with a subtle brownish tint, which Baruah notes is “not 100 percent transparent, but it is semi-transparent. And it’s biodegradable” (quoted by Joseph Shavit).

Although this method uses a number of chemicals, Baruah & Raval say that “these reagents, when used in small amounts, such as in this experiment, pose little threat to the environment” (quoted here). [Ed. – but, what about industrial-scale production of this version of ETW..?] So, while this version of ETW isn’t as chemical-free as one might have expected from an announcement of an improvement in its creation, it does appear to have some environmental advantages over currently-produced ETW. In particular the expectation that this wood will decompose naturally at the end of its use, reducing pollution and waste (Joseph Shavit). Additionally, Baruah emphasizes simplicity and affordability in this research: “[Previous examples of transparent wood are] very hard to synthesize, hard to make, and you spend a lot of time and energy and money… that’s why we thought about creating something we can make easily and naturally” (quoted by Joseph Shavit).

To demonstrate some of the useful properties of this material, Baruah & Raval built a small birdhouse with a single ETW window. “Under a heat lamp, the temperature inside the birdhouse stayed cooler by about 9 to 11 degrees Fahrenheit (5 to 6 degrees Celsius) compared to an identical house with a glass window. This experiment suggests that transparent wood insulates better, meaning homes built with it would stay warmer in winter and cooler in summer, reducing energy bills” (Joseph Shavit). Additionally, this ETW “is renewable, has a lower carbon footprint, and is about five times more thermally efficient [than glass]. Furthermore, it withstands impacts better than glass, bending or splintering instead of shattering dangerously” (Joseph Shavit)

And there’s more. “To further expand the transparent wood’s potential applications, the team also incorporated silver nanowires into certain samples. This addition allowed the wood to conduct electricity, which could be useful for wearable sensors or coatings for solar cells. Silver nanowires aren’t biodegradable, but the team hopes to conduct further experiments using other conductive materials like graphene to maintain their fully natural transparent woods” (from the Press Release).

Is there no end to the utility of wood – and the imagination and inventiveness of inquisitive scientists? [Ed. – for more examples of this, and in a highly readable scicomm item about ETW, see Sid Perkins]

* Balsa is a tree whose utility has been demonstrated in another high-tech way by Van Chinh Tran et al. (2023) who created a transistor whose three terminals were made of ‘conductive wood’ from balsa. For more on this story, see Joseph Shavit.

** In the absence of a published version of this method, Mr P Cuttings is not sure what ‘egg whites’ and ‘rice extract’ actually means. The only clue we have so far is that we are told that Baruah was inspired by ancient buildings in India that are still standing since their construction in the 1500s “using mortar made of sticky rice, egg whites, and sand” (Joseph Shavit). Which sounds like it’s a mixture of whites of egg (but from which species?), and – presumably, cooked – sticky rice. But what are the proportions, is any other material included, how is the rice cooked, etc., etc.?

REFERENCES

Mahiar Max Hamedi et al., 2025. Wood and cellulose: the most sustainable advanced materials for past, present, and future civilizations. Advanced Materials 37(22): 2415787; https://doi.org/10.1002/adma.202415787

Thabisile Brightwell Jele et al., 2023. Engineered transparent wood composites: a review. Cellulose 30: 5447–5471; https://doi.org/10.1007/s10570-023-05239-z

Van Chinh Tran et al., 2023. Electrical current modulation in wood electrochemical transistor. PNAS 120(18): e2218380120; https://doi.org/10.1073/pnas.2218380120