1. European Synchrotron Radiation Facility ESRF, 6 rue Jules Horowitz, F-38043 Grenoble Cedex, France, Römisch-Germanisches Zentralmuseum, Ernst-Ludwig-Platz 2 D-55116 Mainz, Germany, University of Applied Sciences Cologne, Ubierring 40,D-50678 Köln, Germany, and Textile Conservation Centre, University of Southampton Winchester Campus, Park Avenue, Winchester SO23 8DL, United Kingdom