Elemental compositions of papyrus removed from ancient cartonnage reveal technology and date papyrus

Papyrus was used as a writing support from 2500 BC to the 11^th century AD to record and transfer information both in Egypt (where it has predominantly survived) and the wider Mediterranean and Near Eastern world. During the Ptolemaic and early Roman periods in Egypt (c. 322 BC-14 AD), discarded written papyri were recycled and widely used as a support to make cartonnage, which was a glued encasement to protect mummified bodies. This research investigates the elemental characteristics of papyri known or believed to have come from cartonnage, in order to understand how that usage might have changed the elemental compositions of those papyri. In this research, the elemental compositions of ink, no-ink and “white” areas (where observed) were characterised using X-ray fluorescence spectrometry in twenty papyri. Inked areas have significantly greater concentrations of lead than areas of papyri with no ink, and X-ray diffractometry revealed that calcite (CaCO₃) formed the white compound of the preparation layer of the cartonnage. Changes in ink composition may have the potential to be used as a technique for dating papyri.