One of the highlights of 2014 for me was a talk by Peter Vukusic of Exeter University at the Society of Cosmetic Scientist’s meeting on May Day near Oxford. It was about alternative ways of creating colours for cosmetics.
Traditionally cosmetic colours are derived from pigments. These work by absorbing most of the spectrum of white light and reflecting back a single colour. This is a pretty well established technology dating back to before people started writing history down and in all probability predating the emergence of humans in our current form. But it isn’t the only way to create colour. Bird’s feathers and butterflies’ wings use a different technique.
If you can create an ordered structure at about the wavelength of light, it can reflect light of different colours. The colours result from a process called interference and was first explained by Thomas Young. Put at its most simple, it is bit like pulling a comb through porridge to create a pattern that was not there before. In practice the production of these kinds of colours, which biologists call structural colouration is a subtle business that can produce all kinds of effects which it would be impossible to produce in any other way.
The most interesting property of structural colouration for cosmetic purposes is that it is capable of producing very virulent colours from very thin layers. This is indeed exactly what butterflies do. It also has the ability to produce iridescent effects. The traditional means to achieve iridescence is using mother of pearl, which is in fact another biological example of structural colouration. This effect has already been replicated in the form of precisely manufactured plastic sheets that can be added to products like nail polishes.
So the possibilities of butterfly wing cosmetic colours are already being exploited, and there are no doubt many more to come.
Very cool technology. I wonder whether an ingredient like this would be approved as a colorant for cosmetics in the US. The FDA is not strict on much but when it comes to colorants it is.
I think that as they would be neither a dye nor a pigment, and the colour produced is purely an optical effect you could easily argue that they don’t count as colourants. The issue in the EU is that they fit exactly into the official definition of Nano, so they would have to be labelled as such under current regulations. No doubt that will set off the scaremongers.
This is fascinating stuff Colin! You definitely captured my interest – thanks for your inspiration throughout 2014. Happy New Year
Thanks for those kind words Lise, and have a happy and prosperous new year.
For US color regulations, the molecule isn’t what is important, it is the purpose of the compound. For example, if you use a natural extract that creates color in your formula but you’re using it in the formula for some other purpose, it is perfectly ok to use. But if you put that same extract in the formula specifically to color the formula then you can’t use it. Since these ingredients would be specifically put in for their color effect I think there will be some regulatory problems.
Oh I see Perry. That’s a bit of a shame then. But hopefully somebody will work out a way of getting them through when that stage is reached.