1. Department of Chemistry and CSGI, University of Florence, via della Lastruccia 3, Sesto Fiorentino, I-50019 Florence, Italy, Rifinizione Santo Stefano, Textile Finishing Company, Via Arezzo, 35 I-59100 Prato, Italy, and Book and Paper Conservator, via san Cristofano, 22/R I-50122 Florence, Italy