1. Science Section, Conservation DepartmentVictoria and Albert Museum South Kensington London SW7 2RL UK
2. C. Ingold LaboratoriesUniversity College London 20 Gordon Street London WC1H 0AJ UK
3. Physics DepartmentUniversity of Parma Viale G.P. Usberti, 7/a 43100 Parma Italy
4. Paper Conservation Section, Conservation DepartmentVictoria and Albert Museum South Kensington London SW7 2RL UK