Research into the pigmentation of butterfly wings performed by Marco Giraldo at the University of Groningen in the Netherlands may help scientists to create new complex colour effects for use in cosmetics, paint, varnish, and packaging materials. Giraldo has concentrated on the pigmentation of the wings of the cabbage white, and according to the University he is the first to clarify exactly how the colour of the wings is influenced by its nanostructural characteristics. The appearance of the wings is affected by both colour pigments and by nanostructures on the tiny scales that make up the wing, according to Giraldo. Although the characteristics of the scales vary between species, a number of general characteristics can be identified. A scale is made up of two layers, the under surface of which is smooth. However, the upper surface is made up of long, parallel ridges between one and two micrometres apart. According to the research, the colour effect of the wing is dependent on both the absorption of light by any pigments present and the reflection of light by the ridges. The cabbage whites have two layers of overlapping scales. According to Giraldo this is the optimum number as although addition layers would reflect more light it would make the wings too heavy. It is hoped that knowledge of the mechanism behind the pigmentation effects seen in butterfly wings may lead to new methods to reproduce such effects in manufacturing. This is not the first time that colour science has been inspired by nature. In October 2007 scientists at the University of Oxford in collaboration with the Natural History Museum, London, investigated a similar mechanism that lies behind the iridescent pigmentation of the algae diatom. In addition, the scientists led by Professor Andrew Parker investigated the possibilities of farming the diatom as a cheap, green way of producing iridescent effects. "It's a very efficient and cost-effective process, with a low carbon footprint" said Parker, adding that as the shells are biodegradable the environmental impact of the process is minimal. At present the manufacture of products that have this iridescent effect involves the creation of thousands of miniature reflectors, which can be both time consuming and extremely costly.