LISBON, PORTUGAL—According to a statement released by NOVA University Lisbon, an interdiciplinary team of researchers from NOVA University Lisbon, University of Porto, and University of Aveiro followed medieval recipes to recreate a blue watercolor dye called folium, which was used to decorate medieval manuscripts, in order to identify its chemical structure. First, the team members collected the berries of the Chrozophora tinctoria plant, which grows in southern Portugal, and followed the directions to extract, treat, and purify the pigment. In the past, the dye was then stored by soaking it up with a small piece of cloth. When dye was needed, a small piece of the cloth was removed and watered in order to release the pigment for use. The scientists isolated the molecule responsible for producing the blue color, and analyzed it with mass spectrometry, nuclear magnetic resonance, and liquid and gas chromatography. Maria João Melo of NOVA University Lisbon said the structure of the molecule, which has been named chrozophoridine, is unlike that found in indigo and other blue flowers and fruits. The information could help conservators preserve medieval artworks adorned with folium. Read the original scholarly article about this research in Science Advances. To read about a concentration of particles of ultramarine, a blue pigment used for manuscript illumination, found in the dental plaque of a woman buried at a German monastery, go to "Medieval Female Scribe," one of ARCHAEOLOGY's Top 10 Discoveries of 2019.
