L'imbrunimento come criterio di qualità delle carte utilizzate nei libri a stampa dei secoli XV e XVI

The aim of this research is the study, from the point of view of preservation, of a collection ofmore than ten thousand books printed in the 15th and 16th centuries, now kept in the Episcopal Seminary’s Library of Padua. Particular attention was paid to the state of preservation of the paper, singling out the cases where a discolouring of the original white hue had occurred. Such discolouring can take on various gradations, from yellow to brown, which may indicate increasing gravity of degradation. The data detected was then assessed in the light of dates and locations of printing, throwing up evidence of varying behaviour for the books produced in main Italian printing centres and the principal cities of Europe.