It is generally accepted that light can be described in terms of waves or photons that propagate in matter. Light is both a wave and a stream of particles. Physical matter interacts with light and controls the flows of photons in accordance with the rules of photonics.
Generally speaking, colour is the outcome of an interaction between the physical material of pigments and light, but the natural world provides us with numerous spectacular instances of colours in objects that possess no pigments at all.
For example, soap bubbles are iridescent, a smear of oil will take on many hues, Morpho butterfly wings, opals, peacock feathers and many other things appear to have colour despite the fact that the materials that make them up have little or none.
What determines the colour we perceive is in fact the interplay between light and their material structure at the micronic or submicronic level. The optical phenomena involved here have been studied since the time of Newton: they are called interference, diffraction and diffusion.
One of the world's experts on photonics in nature is a physicist at Exeter University, Pete Vukusic, who has been able (thanks to powerful microscopes SEM and TEM) to reveal recently the details of a way of organising matter shaped by the evolution of species of animal, plant and minerals to control flows of photons in the light falling upon them, thus giving rise to shimmering colour and unique visual effects. In recognition of his work he was awarded the L'Oréal Foundation Prize: The Art and Science of Colour in 2004.
L'Oréal, a past master of colour for nearly a century in its products for make-up and hair colouring, set out to find new ideas in natural photonic structures, with the aim of creating a new generation of cosmetics incorporating effects such as Morpho butterfly wing, opal, iridescence, mirror, metallic sheen and so on. This means that the colour of pigments will no longer be crucial and therefore restrictive, and the structure of materials can take over that role.
The challenge has still to be met, involving as it does the production of structures of a sort the natural world took millions of years to develop, but recent progress in materials science allows us to glimpse some possibilities. This is a goal the company has aimed at for a number of years now, but a new generation of powerful microscopes that is helping to unveil the secrets behind this natural phenomenon, combined with major breakthroughs in nanoscience, are helping to make the technology a reality.
'What is amazing about this technology is that we are able to create colour through light and not through pigment,' says Patricia Pineau, L'Oréal research director. 'Put simply, we are able to use nanoscience to control the colour effect by layering the compound's structure. Different gaps in the layers and varying numbers of layers can influence the colour outcome when it is exposed to light.'
'This is amazing when you consider that the basic colour of the product is just white. It brings great advantages for cosmetic applications, being particularly beneficial in lipsticks, as it means that any transfer of the product on to another surface only leaves a white powder trace, not the colour.
Similarly, it also means that the lipsticks can be formulated without having to use the oils that are often used to obtain desirable shimmering effects. Instead this technology can be developed to achieve a similar effect, giving the colour added texture and vibrancy.'
With the technology now reaching the latter stages of its development, Pineau hopes that the first products should launch in early 2006. As the company does not have the production capabilities to produce the materials, it is expected that it will be subcontracted to a company in Japan, where the industry is in a more advanced stage of evolution.
'One problem that we are facing is the packaging of the product,' says Pinea. 'In its manufactured form the product will appear as white, giving little opportunity to display the colour as it will appear when it is applied on the body.
This means that we have to find packaging inks that will give the customer a good idea of what the product will look like when applied. 'We are actually looking at inks that incorporate this same technology, but at the moment this is some way off, and is not likely to appear for the launch of the first generation of products.'
As the technology is still expensive to produce, it is expected that it will primarily be appearing in premium cosmetics products, but as production of the technology becomes more efficient, it should reach mass market products in the longer term.
Pineau adds that the newly developed colour cosmetics have tended to look best on darker skin types, suggesting that it could become particularly popular in the growing market for ethnic cosmetics.
'Most of us are familiar with the tasks of designers. However, few of us are aware of the research, engineering, high-tech equipment and skilled labour that go into actually manufacturing product packaging,' explains Pineau. 'Packages must be conceived so that they don't leak, break or fade, and they must be made of materials that are 100 per cent safe and cause no chemical reaction with contents.'
L'Oréal received 'gratifying recognition' for its design and packaging of Maybelline New York's Roller Colour Eye Shadow, L'Oréal Paris Solar Expertise line of sun care products, Maybelline New York's Sky High Curves Mascara and Ralph Lauren's fragrance Blue. According to Michel Fontaine, vice president of packaging research at L'Oréal, the company's success in packaging is the result of the interaction between brand marketing, the laboratories that produce the formulas and packaging experts.
'We are impressed with how, through the individual style of each brand's packaging, its own distinct personality is conveyed,' Pineau continues. And, in addition to good looks, an important aspect of a great package is functionality - and this is an area in which L'Oréal excels.'
For Maybelline New York's Roller Colour Eye Shadow, L'Oréal invented a specially designed roll-on ball with tiny indentations to ensure the powdered shadow would adhere to it. Sand-proof caps and containers were also designed for the L'Oréal Paris Solar Expertise line of sun care products. Maybelline New York's Sky High Curves Mascara waterproof and washable formulas were packaged in different materials due to the waterproof formulation being more susceptible to evaporation.
'Technological and practical considerations like these are just one aspect of packaging,' notes Pineau. 'Of course, looks count too.'
Interviewee: Patricia Pineau is research director at L'Oréal.