Parallel paths: Designer and materials scientist conjure up glimmering colours out of wood

As a child, Noora Yau was crazy about anything shiny and wondered why the watercolours sold at the store, even the golden ones, always looked so dull.

Our experience of colour is determined by how our brains interpret the wavelengths of the light that hit our eyes.

The majority of substances contain pigments or other colouring agents that reflect some wavelengths away and absorb the rest. The reflected light is scattered randomly in all directions, making the colours look matte and glossless.

Many of nature’s most impressive colours are, however, created without pigments. A butterfly’s wings, a peacock’s feathers and the shell of a beetle are covered by a special nanostructure that gives them iridescent hues and makes them glisten in the sun.    

At Aalto University, Noora Yau and Konrad Klockarsare working on their own, wood-based version of this nanostructure.

The subject was a good match

Their collaboration would probably not have started were it not for a fortunate failure and some coincidences.

‘When I applied for university studies, my first choice at Aalto was technical physics,’ Klockars says.

‘Now, I think it’s good that I didn’t get in – my math skills might not have been up to the standards required at Aalto. And my second choice, bioproduct technology, has proven to be much more interesting than I expected.’

For her part, Noora Yau’s Master’s studies had reached a point where it felt like the things she was designing were cool only for her, but not necessary for the world. Around this time, she was tasked with researching a new material as part of an industrial design course. 

One of the available subjects was structural colour.

‘It really clicked with me, although the only thing I knew about this subject was that it was somehow connected with butterfly wings. I learned about a copepod called sapphirina, a miniscule crustacean in which this effect is unbelievably powerful; viewed from one angle, it can appear entirely transparent or, when seen from another, it looks a very bright blue, like a little gem. I recalled how, as a child, I used to wonder what made things glitter, and the topic started to intrigue me more than I had thought possible.’ 

Yau needed help with her work, so she found her way to Professor Orlando Rojas, a specialist in new biomaterials, who welcomed Yau to in his lab.

During the first six months, Yau pored through a large pile of research papers, panicked slightly and then made small, confidence-enhancing t steps forward in cooperation with postdoctoral researcher Maryam Borghei.

And then Klockars, who was looking for an interesting thesis subject, got in contact with Orlando Rojas.

‘It sounded like a cool subject, and the opportunity to collaborate with a designer on something more than just technical problem solving was enticing.’

Renewable shine

Humans can see light of wavelengths approximately between 400 and 700 nanometres. We perceive the shortest wavelengths as violet and then as blue, green, yellow, orange and red. Typically, the colours we perceive are combinations of several wavelengths. 

However, the nanostructure leading to structural colouring lets all wavelengths through, apart from a single one. That wavelength reflects powerfully in one direction, just like from a mirror, and this is why structural colour is so bright and strong.  

Structural colour can also vary depending on the setting, as the angle it is viewed from determines what wavelength is reflected into the our eyes. From some angles, it can reflect ultraviolet or infrared light that is invisible to the human eye, making the surface completely transparent – in other words, the colour appears to disappear completely.   

Humans have known how to create structural colours since the 1950s. But these glittery colourings and holograms are often made with plastics and metals, many of which contain lead or other toxic substances.   

Yau and Klockars make structural colour out of nanocellulose, which is created by splicing splitting the cellulose contained in wood into nanoscale lengths. One nanometre is equal to one millionth of a millimetre.  

Nanocellulose is non-toxic, environment-friendly and renewable. It is used in, for example, medical applications and composite materials. It can also form a nanostructure that yields structural colour – if you know how to process it.

The colouring experiments of Yau and Klockars have extended into coating metal, plastic, wood and fabric. Their work has drawn appreciation at the Slush event in Helsinki and at the Dutch Design Week in Eindhoven, where professional interior design magazine FRAME highlighted it as one of the most interesting biomaterial innovations.

Yau says combining design with materials research is all the gaining appreciation, but the duo are doing it in an exceptional manner.  

‘Often, a materials scientist will do his or her work, and then pass it on for the designer to perform their share. Both of us of course have our own strengths, but we’re constantly working closely together to develop this thing. Instead of running a relay race, we’re progressing side-by-side on parallel paths.’  

Both praise their good personal chemistry, which enables them to bounce ideas off one another naturally and provides the confidence to ask even dumb questions as many times as is needed.

Humble luxury

Following a couple of years of materials experimentation, Yau and Klockars decided to concentrate on wood. It felt right, as their goal was the creation of a real good-guy material, something that is as ecological as possible.

‘We also noticed that structural colour looked super cool on wood,’ Klockars says.

Wood is a valuable and even luxurious material, but in a humble, measured and down-to-earth way. How does wood, and people’s attitude to it, change when its surface is coated with colour and shine?  

An amused Noora Yau notes that many share her love for glitter, although they may be hesitant hesitate to admit it.

‘The presence of wood immediately makes the glitter different. Several manly men have admitted they admire the colour because it has been made for wood from wood.’

This year, Yau and Klockars have been busy with, among other things, a large wooden wall panel. The aim is to use it to showcase how the different features of their colour can be exploited utilized in design. 

The piece was included in Helsinki Design Week’s exhibition Designs for a Cooler Planet, which showcases projects associated with the United Nations Sustainable Development Goals. In the future, the duo would like to see glowing, renewable and carbon-storing wood used in, for example, furniture and public buildings whose that aim for “wow” architecture aims for the wow factor.

‘Maybe the team of the new design and architecture museum could contact us,’ Noora Yau wonders.

‘It would be great if Finnish research could identify new ways to use wood. At the same time, I hope that the design world gains a better understanding of the significance of cross-disciplinary collaboration, and that this would lead to it being taught more than is presently the case. We can achieve so much more when we don’t have to master every single thing ourselves.’

Text: Minna Hölttä. Photo: Jaakko Kahilaniemi.

This article is published in the Aalto University Magazine issue 27, October 2020.