Multi-technique chemical characterisation of a 12–13th-century painted Crucifix

The Crucifix panel painting in the Santa Maria a Mare church on the Isle of St. Nicholas (Isole Tremiti, Italy), painted on both sides, was executed between the late 12th century and the early 13th century and several times restored in the following centuries. The precious artefact was studied by various complementary analytical techniques in order to characterize the original medieval painting technique and the subsequently applied restoration materials. Optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), micro-Raman spectroscopy, pyrolysis-gas chromatography/mass spectrometry (Py-GC/ MS), and Matrix Assisted Laser Desorption Ionisation–Time of Flight–Mass Spectrometry (MALDI-TOF-MS) were applied on various samples taken from significant parts of the painting. The compositional data were used for a correct planning of the recent restoration treatments and as a support for the historical-artistic study of the painting. The results obtained confirm that both paintings—recto and verso—were realized by following the 13th century Italian painting tradition. Egg-based paint layerswere applied on a gypsum/animal glue ground. Various pigments could be identified amongwhich the precious lapis lazuli. Interestingly, thewater-gilding of the recto was performed without the use of a bole layer. Pinaceae resin as well as acrylic resins were found.