Transparent Wood stars as the race for sustainable materials carries on!

Scientists at the University of Maryland have finally cracked the code to turn ordinary sheets of wood into a material that is nearly as transparent as glass, but stronger and with better insulating properties. With some tweaking, it could very well be the next big sustainable material!

Wood in its most fundamental form is just two things. The first is lignin, a glue-like substance that holds the individual wood fibers together. It also contains the substance that gives wood its earthy brown colour. The other material is cellulose (which provides strength and rigidity to the plant cell wall).

For millennia, wood has aided humankind for multiple purposes, and for good reason. It is relatively cheap, tough, and strong. Moreover, it not only has low density, but we also don’t need to do much to produce it! Just plant a seed in the ground, wait and lo and behold, nature has produced one of its finest materials for free!

Now, you must be thinking, that is good and all, but why go through the trouble to make wood transparent?

“Optically transparent wood is an excellent candidate for lightweight and low-cost structures in light-transmitting buildings and for transparent solar cell windows.”

Scientists had this to conclude after putting the material through vigorous tests. So, now that I’ve got you interested, let’s find out how wood can become glass!

Firstly, scientists experimented by trying to remove the lignin (which also contains the brown pigment). The results were, however, less than satisfactory as the product was fragile, and the process involved high temperatures and hazardous chemicals, ultimately pushing the price point up of such a material.

Frustrated but not giving up, scientists turned to this new method. They not only found it extremely inexpensive but so easy to do that you or I could pick up a paintbrush and begin making transparent wood!

Long and thin planks of wood were taken, and then a hydrogen peroxide solution was brushed on using a paintbrush. This was then left out in the sun.

What happened then was, that our friend, the wood got a skin treatment by the UV rays of the sun and in fact was reverse sunburnt! The hydrogen peroxide acted on the brown pigment and bleached it out, leaving behind a white piece of wood. This white wood was then coated with a layer of special marine epoxy, which was the final step in this plastic surgery.

The wood had turned transparent! They had succeeded at last!

The transparent wood would then go through multiple tests, to check its properties. They found out that

“High optical transmittance of 85% and haze of 71% was achieved at a transparent wood thickness of 1.2 mm.”

or in simpler words, transparency of 85% and distortion of 71%, compared to glass, which has a transparency of 92.5% and distortion of 10%.

These results are quite remarkable, and to a certain extent, unbelievable. As the future draws near, we could see transparent wood replace glass in energy-efficient buildings and be used as solar panel protection.

Scientists state that as the research is scaled up to industrial levels, it could be used to make walls of a house, and we could one day, even have an entirely transparent house! Although, when you think about it, we would much rather prefer our houses built with regular wood…

by Muhammad Faiqh

Li, Yuanyuan, et al. “Optically Transparent Wood From a Nanoporous Cellulosic Template: Combining Functional and Structural Performance.” Biomacromolecules, vol. 17, no. 4, American Chemical Society (ACS), Mar. 2016, pp. 1358–64. Crossref, https://doi.org/10.1021/acs.biomac.6b00145.