Secondary ion mass spectrometry, a powerful tool for revealing ink formulations and animal skins in medieval manuscripts

Book production by medieval scriptoria has gained growing interest in
recent studies. In this context, identifying ink compositions and
parchment animal species from illuminated manuscripts is of great
importance. Here, we introduce time-of-flight secondary ion mass
spectrometry (ToF-SIMS) as a non-invasive tool to identify both inks and
animal skins in manuscripts, at the same time. For this purpose, both
positive and negative ion spectra in inked and non-inked areas were
recorded. Chemical compositions of pigments (decoration) or black inks
(text) were determined by searching for characteristic ion mass peaks.
Animal skins were identified by data processing of raw ToF-SIMS spectra
using principal component analysis (PCA). In illuminated manuscripts from
the fifteenth to sixteenth century, malachite (green), azurite (blue),
cinnabar (red) inorganic pigments, as well as iron-gall black ink, were
identified. Carbon black and indigo (blue) organic pigments were also
identified. Animal skins were identified in modern parchments of known
animal species by a two-step PCA procedure. We believe the proposed method
will find extensive application in material studies of medieval
manuscripts, as it is non-invasive, highly sensitive and able to identify
both inks and animal skins at the same time, even from traces of pigments
and tiny scanned areas.