1. Department of Chemistry and Industrial Chemistry, University of Pisa, via Moruzzi 13, 56124 Pisa, Italy
2. Conservation Department, Tate, Millbank, London SW1P 4RG, United Kingdom
3. Courtauld Institute of Art, Somerset House,
Strand, London WC2R 0RN, United Kingdom
4. Cultural Heritage Agency of The Netherlands (RCE), Hobbemastraat 22, 1071 ZC Amsterdam, The Netherlands