Long-Term Temperature Effects on the Natural Linen Aging of the Turin Shroud

In 2021, Wide-angle X-ray Scattering (WAXS) was applied to a sample of the Turin Shroud as a new method for dating ancient linen threads by inspecting their structural degradation. The major result of the research was to estimate the natural aging of the linen of the Shroud, through which it was found to be compatible with the hypothesis of a 2000-year-old relic, and not a medieval fabric. The present work regards the theoretical natural aging of the linen versus different alleged historical-geographical paths of the Shroud through cities where the presence of icons of Jesus Christ is attested. The theoretical results of the natural aging of the Shroud, calculated for the year 2021, agree extremely well with the experimental results for at least one alleged path. The results also show that if the Shroud were medieval and kept in Europe for 7 centuries, natural aging that is one order of magnitude less than that measured by WAXS would have resulted. Today, the Shroud is kept in a reliquary with a controlled atmosphere, at 19~20 °C temperature, and 50% relative humidity. These values are shown to be unsuitable for maintaining the depolymerization of the cellulose at a level that is sufficiently low enough to preserve the image visible on the Shroud for a long time.