The Science Behind the Sparkle:
A Deep Dive
What if the bright colours of nature could be replicated without harming the planet?
Written By Ariyana Rayatt
Humanity has sought to replicate nature’s vibrant beauty, throughout history, often at a great environmental cost. What if the bright colours of nature could be replicated without harming the planet?
An approach called structural colour is bringing nature’s sustainable colours to a commercial scale. Sparxell is one of the companies producing these sustainable colours across products such as paints, textiles and cosmetics. Unlike the pigments commonly found in more traditional products, Sparxell’s products don’t depend on petroleum and high emissions materials.
The Relationship of Light and Colour
With splashes of colours on our socks and patterns on our cushions, we use colour as a visual form of self-expression. Both people and brands use the relationship between colours and identities to guide their design choices and convey their personalities.
But what about the nature of colour?
Colour is how we perceive light. The light we see is known as white light, but consists of a spectrum of colours, and is best explained with a rainbow. When it rains, the water bends the white light splitting into its coloured components, in other words, a rainbow appears, showing the colours from red to violet.
Light interacts with a soap bubble or the wings of a morpho butterfly in a similar way, changing the colours we see with the angle of the light and the optical properties of a material. This is known as structural colour. A more common way colour is produced is using a colourant, where a particle will absorb some colours of white light and reflect others. It is the reflected colour which we see, for example for a leaf it is green, for a cherry it is red and so on.
It is these interactions of light and the molecular structure of an object that determine colours that paint our world, changing and adapting during its life until it breaks down into the components for new life.
The Dark Side of Traditional Pigments
In contrast to nature’s organic approach, many man-made colourants are derived from petroleum or rely on heavy metals, like cadmium and lead. Their links to high carbon emissions and pollutants put them in the ‘toxic materials’ category. From their production all the way to their degradation, the toxic properties of these materials cause harm to the health and ecosystem of the surrounding people and environment.
Fortunately, scientists are circling back to nature to invent eco-friendly pigments. By studying the relationships between molecular shapes, structures, and light, the scientists at Sparxell have found a way to be more like a morpho butterfly, producing colour without the harmful environmental impact.
How Nanocrystals Interact With Lights
Sparxell’s technology was spun out of a research group led by Professor Vignolini at Cambridge University. Here the group focused on how nature makes structural colour, using microscopic shapes and materials to manipulate light into creating colours, and answer the more pressing question: can this be replicated?
Inspired by the intense blue of a berry, Pollia condensata, Sparxell’s team turned to an organic polymer called cellulose for the answer. This polymer is the building block of plants providing them with strength and structure. When processed, it can be turned into cellulose nanocrystals (CNCs) which have optical properties that can be manipulated to control the reflected light to produce a desired colour.
How does Sparxell use CNCs to produce colour?
“Colour can be tuned based on the properties of the structures the [cellulose nano]crystal made. So basically, the structure that allows us to make a colour is a helix,” Dr Benjamin Droguet, Founder and CEO of Sparxell said, he compared the helix to a spiral staircase, explaining that changes in how wide or narrow the staircase will determine the light reflected and the colour we see.
“So a very compressed structure will reflect a more blue-shifted colour, while a more expanded structure reflects a more red-shifted colour. And so that’s what allows us to have a continuum of colours that we can make from a single ingredient, just by modifying the size of these structures.”
Scaling Up Sustainable Colour
While the Cambridge research group were able to replicate structural colour, this was only done at the scale of a petri dish. Dr Droguet’s research project explored how it can be manufactured at scale for commercial purposes.
“The principle was known, but nobody had done large-scale fabrication with it,” Dr Droguet’s said, he shared how he was met with unforeseen problems as the large-scale equipment unveiled new challenges. Completing his PhD, and the large-scale production of these eco-friendly pigments, Dr Droguet, inspired by the concept of eliminating the toxic effects of synthetic products and offering a naturally derived alternative, founded Sparxell.
Using CNCs made at scale, Sparxell’s team creates pigments that can be used in sequins, paints or packaging. “The process is very similar to paper making. We make basically sheets of paper that are coloured, but without dye, and out of those we can create specific shapes.” Dr Droguet says, “We have this flat format that we can then cut or crush to make the pigment, so the pigment would be just finely crushed sheets of paper”.
What Sparxell’s Will Do With Next With Nature’s Paint Palette
Sparxell has made huge amounts of progress having closed their seed round with £2.5M earlier this year led by the Circular Innovation Fund which was co-founded by the leading cosmetics brand, L’Oreal.
Continuing on its growth trajectory, Sparxell is preparing for a whole range of collaborations including a partnership with Parley as well as joining the LVMH Startup Acceleration Program. These partners are just a couple of the many businesses interested in embracing new materials and reducing the toxic compounds associated with the fashion industry.
As Sparxell continues to grow, it is clear that it stems from Dr Droguet’s mission, “showing that we can learn from nature and do great things with it once we really understand and know how to use the same method that nature uses”.
