A methodological test of external beam PIXE analysis on inks of ancient manuscripts

Extensive scientific investigations on the materials used for preparing inks in medieval and Renaissance manuscripts (before invention of printing) are still missing. With our external PIXE setup, we are beginning such an investigation. The present paper deals with a preliminary methodological research aimed at the identification of the critical compositional parameters and at the definition of operating procedures which permit reliable information to be obtained and in particular the homogeneity of the home-made inks to be checked. We chose three 11th century manuscripts of well known origin. and performed composition measurements on five ink areas on each of six pages per manuscript. On one of the five areas a scan in steps of 200 mum was also performed with the purpose of checking ink composition homogeneity even at this small scale. Five measurements on each of the six pages' parchments allowed us to evaluate the contribution to the collected ''ink'' spectra arising from the underlying parchment. Critical parameters for ink characterization have been found to be e.g. the K contents, the Fe-Cu-Zn Pb compositional pattern, and the sulphur to metals ratio. In addition, we have detected ink-parchment physico-chemical interactions altering the apparent Cl and Ca contents.