Optical features of flax fibers coming from the Turin Shroud

This paper presents a study of flax fibers coming from the TS (Turin Shroud) and evidences their peculiar features if compared with recent ones. A further comparison between image-fibers and non-image-fibers shows both structural and chemical differences especially in correspondence of the external layer about 200 nm thick. The PLM (Polarized Light Microscopy) is used to evidence the various features of the TS fibers, and these features are then explained also at the light of the ancient procedure used to produce fibers from flax plants. Optical microscope and SEM (Scanning Electron Microscope) are used to better show the various fiber's features evidencing the presence of impurities and defects. Finally an opto-chemical analysis is performed showing results of TS fibers relative to CIELAB values, FT-IR ATR and Raman tests also trying to interpret, from a chemical point of view, some peaks present in spectra.