Light Microscopical Study of the Turin "Shroud" I

Sticky tape samples from the linen surface of the Turin Shroud have been studied by light microscopy in an effort to determine the authenticity of this remarkable relic. The 32 tapes, each about 5 cm2 square centimeters in area, retained surface particles and fibers from image, bloodstain, scorch, water stain and control areas. Examination of these tapes in our laboratory during 1979 had the primary objective of learning the chemical nature of the Shroud image. Hopefully, that answer would also reveal the mechanism for formation of that image. Eighteen of these tapes showed significant amounts of a very fine red iron oxide used since prehistoric times as a paint pigment. A blind study separated the 32 tapes microscopically into two groups: those with pigment on the fibers and those without. None of the control samples (those with no image) showed pigment particles whereas 18 body image and blood image areas showed significant amounts of pigment. No significant amount of iron oxide was found on tapes from three body areas but these were areas which showed very little, if any, visible image. All together this is excellent evidence that at least a part of the color in the Shroud image areas is an artist's iron earth pigment. Many fibers in the image areas appeared, in addition to the oxide particles, to be uniformly stained faint yellow to yellow. To determine whether these fibers are also associated with the image we examined more than 8,000 fibers from both image and non image (control) areas to determine the ratio of uniformly stained to colorless fibers. This study showed that the image areas had many more stained fibers (30-72% of the fibers) than the non-image control or the faint image samples (10-26%). This shows that the image is made up of two components: an iron oxide pigment on the fibers and a uniform yellow coloring throughout many of the fibers. These microscopical results are at variance with other data already published by other members of the U.S. scientific team. This other work, based on x-ray fluorescence, reflected visible and infrared spectrophotometry, x-ray radiography and thermography, indicates iron oxide only in blood image areas and also includes results interpreted as indicating blood in the blood image areas. We ascribe the difference in findings by ourselves and the other scientists to the fact we were able to examine much smaller areas, e.g., < 1 μm2 square micrometer, whereas they were limited to aggregated responses over about 1 cm2 square centimeter areas. We know believe that the image is made up of uniformly stained fibers plus an iron oxide pigment. The latter may have been added to from the image or enhance an earlier uniform yellow stain. We will report our results on the uinformly “dyed” yellow linen fibers in a second paper.