Multispectral optical analyses of life-size body images on a linen cloth: recognized an illusion based on color contrast dating back to the XVII century.

Di Lazzaro P., Danielis A., Guarneri M., Missori M., Murra D., Spizzichino V.
  Lunedì 11/09   14:30 - 18:30   Aula A222   VI - Fisica applicata, acceleratori e beni culturali
The linen cloth of the "shroud of Arquata" is a 1:1 copy of the Shroud of Turin conserved in the Church of S. Francis in Arquata del Tronto that dates back to 1653. Apparently, the life-size double body images are not painted and it is therefore interesting to investigate the origin of images and stains on the shroud of Arquata, possibly by non-invasive and contactless technologies in order to preserve its integrity. We have performed $in situ$ analyses of the Arquata Shroud by ultraviolet fluorescence, imaging topological radar, laser-induced fluorescence, ultraviolet-visible-near infrared absolute reflectance, RGB color analyses. The combined results of our measurements and data elaboration identified the origins of the stains simulating blood and of the other marks embedded on the linen cloth, including the subtle technique used by the artist to make a double human figure without using paints or drawings. After our measurements, the city of Arquata del Tronto was almost completely destroyed by several consecutive earthquakes on August, 2016. The church of S. Francis (built in the XII century) has resisted to the repeated earthquakes until the moment when the fire-fighters were able to get inside and to rescue the reliquary containing the shroud, which is now conserved in the Cathedral of Ascoli Piceno. This presentation is dedicated to Arquata's population and to all the people who have been hit by earthquakes.