A greener way to your little black dress

We have all done it ? you put your new black top in for wash but accidentally leave a white shirt in the washing machine.

The colours run, leaving both your black top and your white shirt looking different shades of grey.

But now scientists at the University of Leeds have invented a revolutionary way of permanently colouring the molecules of fabric fibres, meaning that the colours never run and clothes never fade.

The team have created a company, DyeCat, to develop their technology, which offers a more environmentally-friendly alternative to more conventional methods currently used for dyeing clothes.

Dr Patrick McGowan of the University's School of Chemistry and co-founder of DyeCat said: "When clothes are exposed to sunlight and are washed and dried repeatedly, the molecules which colour the cloth begin to detach from the surface of the material and the colours fade.

"If this happens in your washing machine, the molecules may reattach to the other items that they're being washed with - hence your white shirts turns grey and your black top slowly fades and loses colour.

"The DyeCat technology turns the way that textiles are coloured on its head so this doesn't happen. Currently, when clothing is made, the fabrics are usually dyed using chemicals in water baths and it is during this process coloured molecules attach themselves to the fabric and this gives the colour we see. But this uses lots of energy and water and is costly and time-consuming.

"In the DyeCat process we do things differently, we colour the fibre itself- the bit that ends up making up the fabric - as the fibre is made, meaning that the colour is 'locked in' and will never wash out or fade like the traditionally dyed materials."

Currently, many of the clothes produced around the world include polyester, a type of polymer made from oil. But with oil and gas supplies dwindling and an increasing recognition of the environmental damage that can be caused by the extraction and use of oil, the need for alternative materials made from renewable sources has never been greater.

DyeCat's technology uses another type of polymer called PLA, or polylactic acid, which is an alternative to oil-based polymers. PLA is derived from 100% renewable sources, such as maize, and is biodegradable but until now, it has not been used extensively in the commercial production of fabrics, in part because of the problems in dyeing it.

DyeCat, which was founded by Dr McGowan, Professor Chris Rayner both from the University's School of Chemistry and Dr Richard Blackburn of the School of Design, have found a way round this problem.

Dr McGowan explained: "We made a chemical catalyst to which different coloured dyes are added. When the catalyst is added to the lactic acid derived from corn starch or cane sugar, it turns the acid into the PLA polymer and the colour becomes part of the polymer at the same time.

"Because the molecular structure of the PLA is altered at this early stage - as opposed to the polymer being dyed later in a chemical wash - the colour is permanent."

The coloured polymers can be blended with other fibres into textiles and the colours show through, and because PLA occurs naturally, the fibres are biodegradable meaning the clothes can be composted when finished with.

According to Dr. McGowan: "DyeCat has a vision - to improve the performance, environmental impact and sustainability of coloration technology through technical innovation. We have other pieces of technology we are working on including one which allows us to dye materials that are thought of as 'undyeable' and making existing dyeing processes for things like hair dyes fair better."

DyeCat's technology could be used in textiles, clothing and automotive plastics, as well as military and biomedical applications.

There is more information on the DyeCat website www.dyecat.com

For all press enquiries please contact Guy Dixon, University of Leeds media relations - 0113 343 8299 or g.dixon [a] leeds.ac (p) uk

For all commercial enquiries please contact Danny Lynham;

d.lynham [a] dyecat (p) com

About DyeCat

DyeCat are a technology led company with a vision to improve to improve the performance, environmental impact and sustainability of coloration technology through technical innovation. Founded in 2006, DyeCat is a spin out company from the University of Leeds that has developed several technologies that address global issues in safety, sustainability and function in colouration products and processes, which also have wider application. For more information, please go to the DyeCat website at www.dyecat.com

About the University of Leeds

The 2008 Research Assessment Exercise showed the University of Leeds to be the UK's eighth biggest research powerhouse. The University is one of the largest higher education institutions in the UK and a member of the Russell Group of research-intensive universities. The University's vision is to secure a place among the world's top 50 by 2015. www.leeds.ac.uk