Scientists have developed the first environmentally friendly approach to cleaning fragile historic textiles that have seen better days.

Ana Aguiar-Ricardo from the New University of Lisbon, Portugal, and colleagues, used liquid and supercritical carbon dioxide (CO2) as dry cleaning solvents to restore the garments of the Virgin and Child, an eighteenth century sculpture from Necessidades Palace in Lisbon.

The cleaning of antique textiles is often an unavoidable step in their conservation, but many traditional mechanical or wet methods are considered too harsh to use on much deteriorated textiles. In this situation the conservator may decide the risk too great or instead use dry cleaning with perchloroethylene and other toxic organic solvents that remove the dirt and stabilise the textile.

There is an urgent need to preserve our history and cultural heritage. However, to do this art and science must work together so that technological developments do not harm the environment or our quality of life, said Aguiar-Ricardo.

Using CO2 is perfect as it is considered non-flammable, relatively non-toxic and relatively inert: 'It allows the conservation and restoration of the textile without being harmful to the operator and the environment,' said Aguiar-Ricardo. Above a critical temperature and pressure CO2 will become supercritical and have gas-like viscosities and liquid-like densities. Small changes in temperature or pressure cause dramatic changes in its density, viscosity and dielectric properties making it an unusually tunable, versatile and selective solvent.

'What a beautiful application of supercritical carbon dioxide,' said Martyn Poliakoff, an expert on clean technology at the University of Nottingham, UK. 'Scaling this up to work on real objects will provide wonderful opportunities for interdisciplinary research between chemists, engineers and conservators,' he said.

Sarah Corcoran