Investigating the Color of the Blood on the Shroud of Turin (original) (raw)

One of the most puzzling scientific problems of the Turin Shroud (TS) is the reddish color of the bloodstains, despite they are on the linen cloth since several centuries ago, to say the least. We do not know any other old bloodstain on cloths that is still reddish in hue. This simple observation rules out “physiological” explanations and opens two different hypotheses: the bloodstains contain a mix of blood (as found by Baima Bollone and independently by Heller and Adler) and a reddish paint (as found by McCrone), or, in alternative, the blood marks on the TS were exposed to a unique factor that changed the blood chemistry. As an example, Goldoni et al. proposed the hypothesis that the high concentration of bilirubin in the bloodstains on the TS could be responsible for the unusual color of the bloodstains after an irradiation of ultraviolet (UV) light suitable to activate photo-chemistry reactions of bilirubin. Bollone et al. proposed another hypothesis related to the presence of carboxyhemoglobin. In this presentation we will detail two experimental results that test both hypotheses, to some extent. In the first experiment we have irradiated fresh human bloodstains on linen by short UV laser pulses having the same intensity and laser parameters that allow a Shroud-like coloration and latent coloration of linen, and by continuous wave UV blacklamp with intensity below threshold for linen coloration. The blood had very high endogenous bilirubin level, about 8 times larger than the normal range. We have measured the RGB values of bloodstains immediately before and after UV irradiation, and 42 months after irradiation, to check long term effects, if any. This experiment allowed to test the strenght of the Goldoni’s hypothesis. In the second study we have found tiny spectroscopic clues comparing the reflectance spectrum of the blood on the TS measured in 2015 just before the Shroud exhibition with the absorbance spectrum of carboxihemoglobin and methemoglobin. This comparison allowed to assess the strength of the hypothesis by Bollone.