Coloured Ruling Lines in a Fourteenth-Century Ashkenazi Torah Scroll (Erfurt 9; Berlin, Staatsbibliothek, Or. fol. 1218)

Rabbinic halakhah required that Torah scrolls be written with relief ruling, horizontal and vertical lines scored into the writing surface. Coloured ruling with plummet or ink would make a Torah scroll invalid for liturgical use. Ruling lines on some leather fragments of early Oriental Torah scrolls give the impression of being produced with plummet or ink but may be the result of dust in the furrows of relief ruling. Erfurt 9, a fourteenth-century Ashkenazi Torah scroll, has coloured ruling, which is partial secondary re-ruling, on 13 of the 34 surviving sheets, perhaps added when the original relief ruling was difficult to see. The coloured ruling in Erfurt 9 is brown, giving it the visual appearance of iron-gall ink. However, XRF tests showed that the only meaningful metallic component in the coloured ruling was lead (Pb). Lead plummet ruling tends to have a greyish appearance. Black specks under near infrared light are consistent with minium, a lead-based red ink that can turn brown when it degrades. Partial secondary re-ruling added with minium to the original relief ruling comes as a surprise as it would have rendered Erfurt 9 unfit for liturgical use.