Material innovation

Transparent wood – almost like glass

Wood has been a sustainable building block for great architectural feats for thousands of years. It can be used even more flexibly when it is transparent. Transparent wood is not entirely new – but the approach of the team we are presenting is.

May 10 2021

While architects and engineers search for more sustainable, environmentally friendly building materials, researchers at the University of Maryland have now succeeded in transforming ordinary wood panels into a transparent material. This makes wood, a sustainable building material, even more usable. 

Transparent wood as a building material with a future 

The idea of living in a transparent house made of translucent wood may not be everyone's dream. But it could be possible in the future. In the search for sustainable, green building materials, researchers led by Liangbing Hu have succeeded in transforming ordinary wooden boards into a transparent material that they claim is almost as clear as glass.  

The "invisible wood", as Dr Hu describes it, is stronger and lighter than glass and has better insulating properties. Transparent wood is not entirely new, however. Transparent wood has been made before, but earlier attempts required chemicals, high temperatures and a lot of time to remove the lignin, responsible for strength and the brown colour of wood. In addition, the production was expensive and the finished product rather brittle. 

The new technique by Dr Hu and his colleagues is so cheap and simple that it could even be done in one's own garden. A solution of hydrogen peroxide is brushed into metre-long wooden boards, explains the report in the journal Advanced Materials. They are then placed in the sun or under a UV lamp for an hour. This allows the peroxide to bleach out the brown chromophores while the lignin remains intact and the wood turns white. 

© University of Maryland

The next step is to fill the pores of the planks with a tough, transparent epoxy resin, which Dr Hu says can be considered a reinforcing agent. The epoxy fills the spaces and pores in the wood and then hardens, making the white wood transparent. This means that chemicals can be completely dispensed with in this step. 

Clear advantages of the transparent material 

At the end of Dr Hu's process, the result is a piece of wood that transmits more than 90 per cent of light and is more than 50 times stronger than transparent wood that has had the lignin completely removed. The wood is also more insulating than glass and may require less energy to produce. And if cut a little thicker, the wood would be strong enough to become a structural part of a building. 

Although the technology has not yet been scaled up to an industrial level, researchers say it has great potential as a new building material. Find out how trend expert and Managing Director of the Initiative Furnier + Natur. association, Ursula Geismann, views the development in our interview.

In recent years, wood has become one of the most popular materials in the construction industry. The material is used in facades, floors, furniture or also as veneer. How do you assess this development? 

I see this development very positively. Wood is a renewable and natural raw material that stores CO2, which is harmful to the climate. Trees store CO2 as they grow and their wood retains it in the various products for their entire lifetime. Only when wood is burnt does it release the stored CO2 again. Increasing wood use is good for the global climate. 

It is important that forests are climate-stable and reforested as mixed forests and that the whole world adheres to sustainable forest management. Only as much wood should be taken from the forest as will grow back again. The veneer world of fine surfaces favours the special tree species whose cut trunks create a unique image as thin leaves. For veneer plywood, peeled tree trunks are processed into indestructible boards. Both variants conserve the resource wood considerably and can be used in a variety of ways. 

What do you say to the researchers' results of processing wood in such a way that it becomes transparent? How do you classify this new process technology?  

What is new is that this visionary idea now also works in an environmentally friendly way. The development is very gratifying and could trigger a real surge of innovation. Transparent wood with the same stability and strength ... that awakens the spirits. Here, first the researchers, then the engineering teams, architecture firms and design creators can think about it and show where this green path can lead. Transparent veneer has potential for packaging. We could all save a lot of plastic waste and put our veneer packaging in the compost.  

What are the areas of application for material innovation in interior design? Where are the limits? 

When the transparent wood is ready for the market, it can come as a thick board, as a stable veneer plywood or single-layer veneer, as a rod or round bar, as a mullion, and so on. This opens up great new design possibilities in interior design. Furniture frames, such as chairs, could be transparent, as could table tops. Cutting boards in the kitchen would be as clear as glass. Transparent wood could replace all kinds of foils, also dome windows or other transparent plastic applications, for example in LED lamps or lighting.

It could also serve as a semi-transparent partition for the home office and perhaps as a monitor and mobile phone screen. I see its limits in overly humid applications – such as a shower curtain – or in the ground lens of spectacles. I hope it finds its place and one day people will think that such things have always existed. Wood is just great.  

Ursula Geismann is a long-time home expert, trend analyst and design expert. She is the managing director of the international association Initiative Furnier + Natur (IFN). 

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