Sealskin Confirmed as Material for Medieval Book Covers and Parchment

Reseachers examining volumes held by European monasteries have revealed that rather than deer or boar skin, sealskin was used in their construction.

The findings have been laid out in Hiding in plain sight: the biomolecular identification of pinniped use in medieval manuscripts by Élodie Lévêque et al, published in Royal Society Open Science. "Contrary to the prevailing assumption that books were crafted from locally sourced materials," say the researchers, "it appears that the Cistercians were deeply embedded in a global trading network, acquiring skins through extensive trade exchanges. This observation extends beyond just the bindings to include most of the materials used for both the covers and the parchment of the text blocks."

Using methodology known as Zooarchaeology by Mass Spectrometry (eZooMS)43 sealskin books from the 12th and 13th centuries were identified at the French Cistercian monastery of Clairvaux Abbey, founded in 1115 in the Champagne region, and its daughter monasteries in the UK, Belgium, and France, all located inland. The results showed that they used sealskin from seals in Scandinavia, Scotland, Iceland, and Greenland. Protein and DNA analysis on the covers revealed that harbour seals, a harp seal and a bearded seal were among those used in their construction, perhaps because the monasteries were near Norse trading routes.

The Romanesque covers are now brown as they have degraded over time, but the researchers say that it is very unlikely that Cistercians covered their books with brown skins. "Brown was characteristic of the Benedictine order," they write. "Cistercians are known for their affinity with white clothing and objects and, therefore, it is likely that pinniped skins were chosen for the chemises due to their light grey or white coloration... The concept of ‘white’ in this period was understood more as a lack of colour, rather than the bright, pure white we think of today."

There is no records explaining why the monks chose to cover these manuscripts in sealskin, or indeed if they knew that it came from seals.