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On Cleaning Methods and the Raw Radiocarbon Data from the Shroud of Turin

The Shroud of Turin is a long, narrow strip of linen cloth believed by many to be the burial cloth of Jesus. The Shroud is unique because faint images of a crucified man are clearly visible on one surface. These body images along with accompanying blood stains have been the subject of scientific inquiry for over a hundred years, yet the process of the image formation has been and remains unknown. Among the more recent of coordinated studies of the Shroud was a radiocarbon dating of excised samples. The results, published in 1989, place the origin of the cloth to sometime in or around the 14th century. The objective of the present study is to survey the cleaning methods (or pretreatments) that were applied to the samples removed for the radiocarbon study. Specifically, we explore the extent to which these methods may have given rise to a peculiar structure in the "raw" radiocarbon data published in 2019. The data from two of the participating laboratories, Zurich and Arizona, appear to bifurcate into groups separated by roughly 100 radiocarbon years. By comparing the pretreatment for each subsample and its group membership, we conclude that these pretreatments do not account for the bifurcation effect. As all subsamples represent portions excised from an originally intact and continuous sample of Shroud material, we assume they are all the same calendar age. Granted this assumption and given the results of the present study, two hypotheses remain to account for the curious anomaly: either 1) the carbon isotope ratios 14C/12C of the fabric itself were altered by some currently unknown process, or 2) a non-isotropic distribution of contamination remained after the samples underwent the documented pretreatments. A resolution of the question is important for deciding whether future radiocarbon studies are called for and, if so, how the testing protocols should be structured.

Shroud, Radiocarbon, Inter-laboratory, Statistics, Pretreatment

APA Style

Larry Schwalbe, Bryan Walsh. (2021). On Cleaning Methods and the Raw Radiocarbon Data from the Shroud of Turin. International Journal of Archaeology, 9(1), 10-16.

ACS Style

Larry Schwalbe; Bryan Walsh. On Cleaning Methods and the Raw Radiocarbon Data from the Shroud of Turin. Int. J. Archaeol. 2021, 9(1), 10-16. doi: 10.11648/j.ija.20210901.12

AMA Style

Larry Schwalbe, Bryan Walsh. On Cleaning Methods and the Raw Radiocarbon Data from the Shroud of Turin. Int J Archaeol. 2021;9(1):10-16. doi: 10.11648/j.ija.20210901.12

Copyright © 2021 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License ( which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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